....... /; L \^ ,...,....., , f m w BIOLOGY LIBRARY The Natural History of Animals KINGFISHERS (ALCEDO ISPIDA) KINGFISHERS (Alcedo ispida} The Common Kingfisher of Britain, which ranges through Europe and the greater part of Asia, is remarkable for its brilliant plumage. The plate depicts two of them perched on branches overhanging a stream, on the look-out for fish, which constitute their favourite prey. The structure of the feet greatly assists in the maintenance of this characteristic attitude, three of the toes being closely bound together and forwardly directed. On sighting its prey the Kingfisher darts down with arrow-like flight, and uses its long sharp beak as a fish-spear. Once secured the booty is taken from the water and beaten against the branch to stop its struggles, as a preliminary to swallowing. Kingfishers also hawk along the surface of the water, diving vertically with great rapidity as opportunity may offer. When the wings are closed the extended body is shaped like a rounded wedge, well suited for cleaving the water with but little friction. The Natural History of Animals The Animal Life of the World in its various Aspects and Relations BY J. R. AINSWORTH DAVIS, M.A. TRINITY COLLEGE, CAMBRIDGE PROFESSOR IN THE UNIVERSITY OF WALES, AND PROFESSOR OF ZOOLOGY AND GEOLOGY IN UNIVERSITY COLLEGE, ABERYSTWYTH HALF-VOL. Ill LONDON THE GRESHAM PUBLISHING COMPANY 34 SOUTHAMPTON STREET, STRAND 1903 BIOLOGY LIBRARY G ''''"' ''' f /'' ',/' "* r ^ /'r CONTENTS HALF-VOL. Ill THE FOOD OF ANIMALS Page INTRODUCTORY I CHAPTER I.— THE FOOD OF ANIMALS— FLESH-EATING MAMMALS (CARNIVORA)— WHALES (CETACEA) FLESH-EATING MAMMALS (CARNIVORA) A. TERRESTRIAL CARNIVORES (FISSIPEDIA) 1. CAT FAMILY (Felidae) — Common Cat, Lion, Leopard, Tiger, Jaguar, Puma, Hunting Leopard, Fishing Cat ----------5 2. CIVET-CAT FAMILY (Viverridse)— Foussa, Civet-Cats proper, Mampalon, Man- goustis - II 3. HYAENA FAMILY (Hyaenidae) — Ordinary Hyaenas, Earth- Wolf or Aard-Wolf - 14 4. DOG FAMILY (Canidae) — Dogs, Wolves, Jackals, and Foxes - - - - 15 5. LARGE BEAR FAMILY (Ursidac) — Polar Bear - - - - - - 19 6. WEASEL FAMILY (Mustelidae) — Glutton, Weasels, Polecats, Martens, Stoats, Otters - 20 B. AQUATIC CARNIVORES (PINNIPEDIA) General Characters; 7. SEAL FAMILY (Phocidae); 8. SEA-LION FAMILY (Otaridse); 9. WALRUS FAMILY (Trichecidas) - - 24 PORPOISES, DOLPHINS, AND WHALES (CETACEA) General Characters - - .... 25 A. TOOTHED WHALES (ODONTOCETI) 1. DOLPHIN FAMILY (Delphinidas) — Porpoise, Killer- Whale, Common Dolphin, Fresh-water Dolphins - 26 2. SPERM-WHALE FAMILY (Physeteridae)— Sperm- Whale or Cachalot - - 29 B. TOOTHLESS OR WHALEBONE WHALES (MYSTACOCETI) Rorqual, Right or Greenland Whale 29 vi CONTENTS CHAPTER II.— THE FOOD OF ANIMALS— MAMMALS WHICH CHIEFLY FEED ON INSECTS AND OTHER SMALL CREA- TURES Page INSECT-EATERS PROPER (Insectivora) — General Characters; Hedgehog, Tenrecs, Golden Moles, Shrews, Desmans, African River-Shrew, Mole-Shrews, Common Mole, Star-nosed Mole, Tree-Shrews, Elephant-Shrews - 31 BATS (Cheiroptera) — General Characters; Long-tongued Vampires, Long-tongued Shrew-Bat, True Vampires, Javelin Bats 38 CHAPTER III.— THE FOOD OF ANIMALS— LOWER MAMMALS WHICH CHIEFLY FEED ON INSECTS \ND OTHER SMALL CREATURES MAMMALS POOR IN TEETH (Edentata) — Great Ant -Eater, Cape Ant -Eater or Aard-Vark, Scaly Ant-Eaters or Pangolins ... - 41 POUCHED MAMMALS (Marsupialia) — Banded Ant-Eater, Bandicoots, Marsupial Mole 42 EGG-LAYING MAMMALS (Monotremata)— Spiny Ant-Eaters - - - - 44 CHAPTER IV.— THE FOOD OF ANIMALS— CARNIVOROUS BIRDS Ancient Toothed Birds; Birds of Prey — Falcons, Owls, Secretary Bird, Osprey or Fishing-Eagle; Fish-eating Birds — Cormorants, Darters or Snake- Birds, Gannet, Pelicans, Gulls and Terns, Skuas, Scissor-Bills or Skimmers, Frigate- Birds, Albatrosses, Storm Petrels, Divers, Penguins, Kingfishers, Herons, Storks - - 45 CHAPTER V.— THE FOOD OF ANIMALS — BIRDS WHICH CHIEFLY FEED ON INSECTS AND OTHER SMALL CREA- TURES—SCAVENGERS Birds that feed on Insects, &c. — Swallows and Swifts, Night-Jar or Goat-Sucker, Woodpeckers, Cuckoo, Creepers, Blue-Roller, Fly-Catchers, Tyrant Fly- Catchers, Ox-Peckers, Honey-Guide, Huia, Shrikes or Butcher Birds, Ducks and Swans, Wagtails, Turnstone and Oyster- Catcher, Godwits and Curlews, Woodcock, Kiwi ... - 56 Scavenging Birds — Vultures and Adjutants --------69 CHAPTER VI.— THE FOOD OF ANIMALS— CARNIVOROUS AND INSECTIVOROUS REPTILES CROCODILES (Crocodilia)— Nile Crocodile, Garials 70 TORTOISES AND TURTLES (Chelonia)— Snapper Tortoises, Hawk-bill Turtle, Snake- necked Tortoises ----.__. . _ . _ 71 LIZARDS (Lacertilia) — Monitors, Geckoes, Chameleons, Skinks, Amphisbaenas, Snake-like Lizards - - - - - - - - - - - -73 SNAKES (Ophidia)— General Characters; Grass Snake, Pythons and Boas, Shield- tailed Snakes and Blind Snakes; Poisonous Snakes — Whip-Snakes, Coral- Snakes, Cobras, Asps, Death-Adders, Sea-Snakes, Adder, Puff-Adder, Rattle- snake - - 76 CONTENTS vii CHAPTER VII.— THE FOOD OF ANIMALS-AMPHIBIANS AND FISHES OF CARNIVOROUS AND INSECTIVOROUS HABIT Page AMPHIBIANS (Amphibia) — Grass Frog, Common Toad, Tree-Frogs, Spotted Sala- mander, Newts and Fish-Salamanders, Caecilians ------ 82 FISHES (Pisces) — Lung-Fishes or Mud-Fishes (Dipnoi). Ordinary Bony Fishes (Teleostei) — Perches, Mackerels, Pike, Angler-Fish or Fishing-Frog, Deep-sea Angler, Wrasses and Wolf-Fishes, Electric Cat-Fishes and Electric-Eel, Mud- Skippers, Beaked Chelmon. Sharks and Rays (Elasmobranchii) — Blue Shark and Rondeletian Shark, Thresher, Saw-Fishes, Port Jackson Shark, Eagle- Ray, Electric- Rays. Round-Mouths (Cyclostomata) — Lampreys and Hags - - 83 CHAPTER VIII.— THE FOOD OF ANIMALS— NEMERTINES AND CARNIVOROUS MOLLUSCS NEMERTINE WORMS (Nemertea) 93 MOLLUSCS (Mollusca) — Cuttle-Fishes and Squids (Cephalopoda) — General Charac- ters. Snails and Slugs (Gastropoda) — General Characters ; Purple-Shell, Common Whelk, Cone-Shells, Natica, Heteropods, Tectibranchs, Sea-Slugs, Lung-Snails ------------ -94 CHAPTER IX.— THE FOOD OF ANIMALS- CARNIVOROUS INSECTS General Characters. Membrane -winged Insects (Hymenoptera) — Driver- Ants, Foraging- Ants, Sand-Wasps, Ichneumon-Flies. Beetles (Coleoptera)— Tiger- Beetles, Ground-Beetles, Rove-Beetles, Water-Beetles, Lady-Birds, Scavenging Beetles. Net-winged Insects (Neuroptera) — Biting-Lice, Snake-Flies, Scorpion- Flies, Ant-Lions, Mantis Net-Wings, Lace-wing Flies, Golden-eyed Flies, Dragon-Flies, May-Flies and Stone-Flies, Caddis-Flies. Straight -winged Insects (Orthoptera) — Soothsayers or Praying Insects. Scale-winged Insects (Lepidoptera) — Fur-eating Caterpillars, Purple Emperor Moth. Two-winged Flies (Diptera)— Stable- Fly, Tsetse-Fly, Gad-Flies, Gnats and Midges, Forest- Flies, Fleas. Bugs (Hemiptera) — Land-Bugs, Water-Bugs, Marine Bugs, True Lice ---ioi CHAPTER X.— THE FOOD OF ANIMALS -CARNIVOROUS ARACHNIDS AND MYRIAPODS— PERIPATUS SPIDER-LIKE ANIMALS (Arachnida) — Scorpions (Scorpionidas). Whip-Scorpions (Pedipalpi). Spiders (Araneidae)— General Characters; Web-Spinners, Bird- catching Spiders, Wolf- Spiders, Water- Spiders, Jumping Spiders. False Spiders (Solpugidae). False Scorpions (Pseudoscorpionidae). Harvestmen (Phalangidae). Mites and Ticks (Acarina) 125 MANY-LEGGED ANIMALS (Myriapoda): Centipedes (Chilopoda)— Thirty-Foot, Tropical Centipedes, Earth Centipedes, Shield-bearing Centipedes - - 132 PRIMITIVE AIR-BREATHERS (Prototracheata)— Peripatus - - - - 134 CHAPTER XL— THE FOOD OF ANIMALS— CARNIVOROUS CRUSTACEANS AND KING-CRABS CRUSTACEANS (Crustacea): Higher Crustacea (Malacostraca) — Long-tailed Deca- pods— Lobster, Prawn, Shrimp, Crayfish, Jamaica Prawn, Rock-Lobster, viii CONTENTS Page Hermit- or Soldier-Crabs; Short-tailed Decapods — Common Crabs, Gulf-weed Crab, Swift Land-Crabs. Mantis-Shrimps (Stomatopoda). Sessile-eyed Crus- tacea (Edriopthalmata) — Sand-Hoppers, Skeleton-Shrimps, Slaters. — Lower Crustacea (Entomostraca), Parasitic Forms - - 135 KING-CRABS (Xiphosura) 144 CHAPTER XII.— THE FOOD OF ANIMALS-CARNIVOROUS ANNELIDS AND SIPHON-WORMS ANNELIDS (ANNELIDA) BRISTLE- WORMS (Chaetopoda)— Sea-Centipede, Sea-Mouse 146 LEECHES (Discophora) : Jawed Leeches — Medicinal Leech, Land-Leeches ; Jaw- less Leeches— Horse-Leech - ... - 147 SIPHON-WORMS (GEPHYREA) Common Siphon- Worm, Bristly Siphon- Worms, Green Bonellia - - 149 CHAPTER XIII.— THE FOOD OF ANIMALS— CARNIVOROUS UNSEGMENTED WORMS AND ECHINODERMS PLANARIAN WORMS (Turbellaria) - 151 HEDGEHOG-SKINNED ANIMALS (Echinodermata)— Common Star-Fish - - - 153 CHAPTER XIV.— THE FOOD OF ANIMALS— ZOOPHYTES, SPONGES, AND PROTOZOA ZOOPHYTES, &c. (Ccelenterata). Comb-Jellies (Ctenophora) — Cydippe, Beroe. Sea-Anemones and Typical Corals (Anthozoa). Zoophytes, Jelly-Fish, and Millepore Corals (Hydrozoa) - - 155 SPONGES (Porifera) AND ANIMALCULES (Protozoa) 163 CHAPTER XV.— THE FOOD OF ANIMALS— PLANT-EATING MAMMALS MAN AND MONKEYS (Primates) — Entellus Monkey - - 164 HOOFED MAMMALS (Ungulata): Odd-toed Ungulates (Perissodactyla)— Horse, Tapir, Rhinoceros ; Even-toed Ungulates (Artiodactyla) — Ruminants or Cud- Chewers — Ox, Goat, Blue-Buck, Giraffe, Okapi, Camel; Hippopotamus - - 165 ELEPHANTS (Proboscidea) - 171 SEA-Cows (Sirenia) — Manatee, Dugong, Rhytina - 173 GNAWING MAMMALS (Rodentia): Rabbits and Hares, Dormice and Squirrels, Beavers, Voles, Lemmings and Hamsters, Mole-Rats, Porcupines, Cavies 174 MAMMALS POOR IN TEETH (Edentata)— Sloths - 178 POUCHED MAMMALS (Marsupialia) : Fruit-eating Marsupials— Typical Phalangers, Koala or Native Bear, Long-snouted Phalanger (a honey-eating form) ; Herbi- vorous Marsupials — Kangaroos; Root-eating Marsupials — Wombats - - 180 CONTENTS ix CHAPTER XVI.— THE FOOD OF ANIMALS— PLANT-EATING BIRDS, REPTILES, AMPHIBIANS, AND FISHES Page BIRDS (Aves) : General Characters. Pigeons — Ground- Pigeons (Turtle- Dove, Crowned-Pigeons), Tree-Pigeons (Wood-Pigeon, Stock-Dove, Fruit-Pigeons). Toucans. Crows — Nutcracker, Nuthatch. Finches and Crossbills. Oil-Birds. Parrots — Owl-Parrot, Slight-billed Parraquet, Great Black Cockatoo, Ka-ka and Kea Parrots, Lories and Loriquets 184 REPTILES (Reptilia) : Turtles and Tortoises (Chelonia) — Green Turtle, Land Tortoises. Lizards (Lacertilia) — Iguanas, Sea-Lizard, Galapagos Land-Lizard - 191 AMPHIBIANS (Amphibia)— Tadpoles - 192 FISHES (Pisces)— Sea-Breams, Beaked Carp - - 194 CHAPTER XVII.— THE FOOD OF ANIMALS— PLANT-EATING MOLLUSCS SNAILS AND SLUGS (Gastropoda)— General Characters. Limpets, Land-Snails and Slugs - - 196 CHAPTER XVIII.— THE FOOD OF ANIMALS— PLANT-EATING INSECTS, ARACHNIDS, AND MYRIAPODS INSECTS (Insecta) : Membrane-winged Insects (Hymenoptera) — Saw-Flies, Giant Wood- Wasp, Turnip Saw-Fly, Gall-Flies, Bees, Wasps, Honey-Ants, Harvesting Ants, Leaf-cutting Ants. Beetles (Coleoptera) — Cockchafer, Sacred Scarab, Click-Beetles or Skipjacks, Pea- and Bean-Beetles, Potato-Beetle, Weevils. Net-winged Insects (Neuroptera) — Termites or White Ants. Straight- winged Insects (Orthoptera). Primitive Wingless Insects (Aptera) — Tassel-Tails and Spring-Tails. Scale-winged Insects (Lepidoptera) — Cabbage White Butterfly, Silk Moth, Small Tortoiseshell Butterfly, Peacock Butterfly. Two-winged Flies (Diptera)— Crane-Flies, Hover-Flies, Drone-Flies. Fringe-winged Insects (Thysanoptera) — Corn Thrips. Bugs (Hemiptera) — Cicadas, Plant-Lice or Aphides, Frog-Hoppers ----------- 202 SPIDER-LIKE ANIMALS (Arachnida) : Mites — Meal-Mite, Gall-Mites, Money-Spider 217 MANY-LEGGED ANIMALS (Myriapoda)— Millipedes 218 CHAPTER XIX.— THE FOOD OF ANIMALS— PLANT-EATING CRUSTACEANS AND LOWER INVERTEBRATES CRUSTACEANS (Crustacea) — Countryman-Crab, Robber- or Cocoa-nut-Crab, Chelura, Gribble, Wood-Lice ------------ 220 THREAD-WTORMS (Nemathelmia) — Vinegar- or Paste-Eel, Wheat Eelworm - - 222 CHAPTER XX.— THE FOOD OF ANIMALS— OMNIVOROUS MAMMALS General Characters. MAN AND MONKEYS (Primates). LEMURS (Lemuroidea) - 224 FLESH-EATING MAMMALS (Carnivora) : Palm-Civets ; Bears— Malayan Bear, Brown Bear, Sloth-Bear; Small Bears — Raccoons, Coatis or Proboscis Bears; Weasels — Badgers, Ratels or Honev-Badgers ------- 226 HOOFED MAMMALS (Ungulata): Swine — Wild Boar, Peccaries - - - - 231 GNAWING MAMMALS (Rodentia) — Rats and Mice. MAMMALS POOR IN TEETH (Edentata)— Hairy Armadillo. POUCHED MAMMALS (Marsupialia)— Some Phalangers, Bandicoots, Opossums - 234 x CONTENTS CHAPTER XXL— THE FOOD OF ANIMALS— OMNIVOROUS BIRDS AND PRIMITIVE VERTEBRATES Page BIRDS (Aves): Crows, Starlings; Geese, Ducks, and Swans; Game-Birds — Quail, Partridge, Pheasant, Peacock, Red Jungle- Fowl, Guinea- Fowl, Turkey, Caper- cailzie, Grouse; Rails — Land-Rail or Corncrake, Moor-Hen, and Coot; Cranes, Trumpeters, and Bustards. Running Birds — African Ostrich, American Ostriches, Emeu - - - 235 PRIMITIVE VERTEBRATES (Protochordata) — Sand and Mud Swallowing, Ciliary Currents. Lancelets. Sea-Squirts or Ascidians. Worm-like Protochordates — Acorn-headed Worm - 243 CHAPTER XXII.— THE FOOD OF ANIMALS— OMNIVOROUS MOLLUSCS, INSECTS, AND CRUSTACEANS MOLLUSCS (Mollusca) : Snails and Slugs (Gastropoda)— Grey Field-Slug, Black Slug. Tusk-Shells (Scaphopoda). Bivalve Molluscs (Lamellibranchia)— Fresh- water Mussels, Cyclas, Sand-Gapers 247 INSECTS (Insecta): Straight-winged Insects (Orthoptera) — Cockroaches, Earwigs. Membrane-winged Insects (Hymenoptera) — Social Wasps, Bees, and Ants. Two-winged Flies (Diptera)— House- Fly. Scale-winged Insects (Lepidoptera) — Omnivorous Caterpillars - - - 250 CRUSTACEANS (Crustacea) : Higher Crustacea (Malacostraca) — Crayfish, West Indian Fresh -water Prawn; Lower Crustacea (Entomostraca) — Barnacles, Copepods, Mussel-Shrimps, Leaf-footed Crustacea 253 LIST OF ILLUSTRATIONS HALF-VOL. Ill COLOURED PLATES KINGFISHERS (Alcedo Ispidd). From a Drawing by A. Fairfax Muckley Frontispiece. LION SEIZING PREY (Felts led). From a Drawing by W. Kuhnert BRITISH SEA-SLUGS (Nudibranchs) (after Alder and Hancock). A Study by A. Fairfax Muckley AUSTRALIAN SEA- ANEMONES AND CORALS (after Saville Kent). A Study by A. Fairfax Muckley ARGENTINE TOUCANS (Rhampkastus Toed}. From a Drawing by W. Kuhnert 10 IOO 158 1 86 BLACK-AND-WHITE ILLUSTRATIONS Page Metabolic Staircase 3 Digit of Cat 6 Skull of Cat 7 Markings of Cat-like Animals 8 Puma (Felis concolor) 9 Cheetah or Hunting Leopard (Cyn&htrus jubatus} n Foussa (Cryptoprocta ferox) - - - 12 Mampalon ( Cynogale Bennetti] - - 13 Spotted or Laughing Hyaena (Hycena cro- cutd) 14 Jaws of Dog (Cants) and Pouched Wolf (Thylacinus} 1 6 A PACK OF WOLVES ( Cants lupus) - 16 Vizcacha (Lagostomus trichodactylus) - 17 The White or Arctic Fox (Cants lagopus) - 18 THE POLAR BEAR (Ursus maritimus) - 20 Stoats (Miistela ermined) and Weasels (M. vulgaris) in summer dress - - - 21 Stoats (Mttstela erminea) and Weasels ( M. vulgaris) in winter dress 22 Otter (Ltitra vulgaris} 23 Page Skulls of Seal and Walrus 25 Killer-Whale ( Orca gladiator) 26 Dolphin (Delphinus delphis] - - - 27 Fresh- water Dolphin ( Platanista Gauge tica ) 28 Baleen or Whalebone 30 THE GREENLAND OR RIGHT WHALE (Balcena mysticetus] 30 Skull of an Insect-eating Mammal (Hedge- hog) - 31 Hedgehog (Erinaceus Europcuits) and Young 32 Common Tenrec (Centetes ecaudatus) - 33 Cape Golden Mole ( Chrysochloris Capensis) 34 Garden- Shrew (Crocidura aranea) - - 35 Hairy-tailed Mole-Shrew (Urotrichus) - 36 Common Mole ( Talpa Europcea) - - 36 Star-nosed Mole ( Condylura cristata) - 37 Head of Long-tongued Vampire (Chcero- nycteris] (after Dobson) - - - 38 A Javelin-Bat (Phyllostoma spectrum) - 39 Great Ant-Eater (Myrmecophaga jubata) - 41 Marsupial Mole (Notoryctes typhlops) - 43 Spiny Ant- Eater (Echidna] 43 Xll LIST OF ILLUSTRATIONS Page Head of an extinct Toothed Bird (Hesper- ornis regalis] (after Marsh) - - - 45 A Falcon preying upon Lemmings - - 46 A Secretary- Bird (Serpentarius secretarius] attacking a Snake - - - - 47 A Darter (Plotus] 49 A Pelican (Pelecanus] 50 Gulls and Terns 51 Skua (Stercorarius] 51 Scissor-Bill (Rhynchops] hunting - - 52 Frigate-Bird (Fregatus] • - - 53 Red-breasted Merganser (Mergus serrator] and Black - throated Diver (Colymbus arcticus] 54 Night-jar ( Caprimulgus Etiropceus] - - 56 Greater Spotted Woodpecker (Dendrocopus major] 58 Common Creeper ( Certhia familiaris] - 59 Blue Roller ( Coracias garrulus] - 60 Crowned Tyrant (Muscivora regia] - - 6 1 African Ox-Pecker (Buphaga Africana] - 62 White-eared Honey-Guide (Indicator Spar- manni] ------ 63 Huias (Heteralocha Gouldi] 64 Great Butcher-Bird (Lanius excubitor] - 65 Head of Duck (Anas boschas] 65 Yellow Wagtail (Motacilla flava] - - 66 Black-tailed Godwit (Limosa Belgica] - 66 Curlew (Numenius arquatus] 67 Woodcock (Scolopax rusticola] 68 Hawk-bill Turtle (Chelone imbricata] • 72 Chameleon seizing its Prey 74 Tunisian Lizards 77 POISONOUS ASIATIC SNAKES 78 Skull of Rattlesnake - 80 Tongue of Frog extended to secure its Prey 82 Toad catching its Prey 83 Angler-Fish (Lophius piscatorius] - - 85 Deep-sea Angler (Melanocetus Murrayi] - 86 Cross-section through Electric Eel - - 87 Saw-Fish (Pristis antiqtwrum) - - 89 Port Jackson Shark ( Cestracion Philippi] - 89 Eagle Ray (Myliobatis aquila] - - - 90 Electric Ray (Torpedo) 90 Suctorial Mouth of Lamprey (Petromyzon] 91 Hag- Fish (Myxine glulinosa] - - 91 Front End of Nemertine, with Proboscis partly protruded 93 Beaks of Cuttle-Fish (Sepia officinalis] - 95 A Single Row of Teeth from Radulse of Carnivorous Snails - - - - 96 The Purple-Shell (Purpura lapillus] - 97 Barbed Poison -Tooth from Radula of a Cone (Conus] 97 A Boring Carnivorous Sea-Snail (Natica Tosephina] ------ 08 Page Bivalve Shells bored by Natica - - 98 Heteropods 99 Foraging- Ants (Eciton hamata] on the march 104 Bird-catching Spider (Mygale) threatened by a Sand- Wasp (Pepsis] • 106 Newts and Fresh- water Insects - - 108 Scavenging Beetles 109 The Ant-Lion (Myrmeleo formicarius] - 112 Mantis Net -Wing (Mantispa areolaris] (after Westwood) 113 Praying Mantis* (Mantis religiosa] - - 117 Flies (Dipterd) 119 Tsetse- Fly (Glossina morsitans] - - 120 Mouth-parts of a Female Gnat (Cttlex) (after Becher) 121 The Common Flea (Piilex irritans} - - 122 Mouth-parts of a Tree-Bug (Cicada] en- larged 122 Larva of Reduvius personatus - - - 123 A Pond -Skater (Gerris paludum] en- larged 123 A Marine Bug (Halobates] (after Challenger Report) 124 Spinnerets of Spider (greatly enlarged) - 127 A House-Spider ( Tegenaria] in its Web - 129 Hunting Spiders (Salticus scenicus] - - 131 Shield-bearing Centipede (Scutigera) (after Buffon) 133 Gastric Mill of Crayfish - ... 136 Hermit Crabs (Pagurus Bernhardus] - 138 Swift Land Crab (Ocypus] - • - 140 Sea-Slater (Ligia oceanica] ... 143 Sea-Mouse (Aphrodite acideata] - - 147 Structure of Medicinal Leech (Hirtido me- dicinal is] (after Leuckart and Hatschek) 148 Green Bonellia (Bonellia viridis] - -150 A Triclade Planarian with Pharynx pro- truded - - 152 Beroe - 156 A Sea- Anemone 156 Thread-Cells 158 A Branching Coral - - - - 159 A Hydroid Zoophyte (TtibuZaria] - - 160 Group of Individuals from a Millepore Coral (Millepora] (after Moseley) - - 161 A Compound Jelly-Fish (Physophora hy- drostatica] (after Haeckel) - - - 162 Grinding-Teeth of Horse (Equus cabalhis] 166 Stomach of Sheep (Ovis aries] - - - 168 The Okapi (Okapia Johnstoni] - 170 Grinders of African and Indian Elephants 172 THE INDIAN ELEPHANT (Euelephas In- dictis] 172 The Dugong (Halicore dugong] - - 174 Hares (Lepus timidus] - - - 175 Abnormal Skull of Hare (Lepus timidus] • 1 76 LIST OF ILLUSTRATIONS Xlll Page The Common European Mole-Rat (Spalax typhhis} 177 Three-toed Sloth (Bradypus tridactylus] - 179 The Koala (Phascolarctos cinereus) - - 180 The Long -snouted Phalanger (Tarsipes restrains] 181 The Wombat (Phascolomys wombat] - • 183 Stomach of a Crane - - - - 184 The Crossbill (Loxia curvirostra) - - 1 88 Great Black Cockatoo (Microglossus ater- rimus] 189 The Kea Parrot (Nestor notabilis] - - 190 West Indian Ring-tailed Iguana (Cyclura carinatd) - - - - - 193 Tadpoles 194 Single Rows of Teeth from Radulae of Plant-eating Sea-Snails ... 196 A Limpet (Patella vulgata] leaving its Scar at Ebb-tide - 197 Land-Snails and Slugs . . . 200 Hinder-end of a Saw-Fly (after Lacaze- Duthiers) 204 Rose Gail-Fly (Rhodites roste)a.nd Bedeguars 204 Honey- Ant (Myrmecocystus Mexicanus] - 207 A Leaf-cutting Ant (CEcodoma) carrying a piece of Leaf (after Poulton) - - 208 A Bug which mimics a Leaf-cutting Ant and its Burden (after Poulton) - - 208 The Sacred Scarab (Scarabtzus sacer) Nut-Weevil (Balaninus nucum} Termites or White Ants - Heads of Butterflies Jaws of a Millipede (after Koch) Page - 2IO - 211 - 212 - 214 - 218 Robber - or Cocoa - nut - Crab (Birgus latro) 221 Wheat- Eelworm (Tylenchus scandens) - 222 Palm-Cat (Paradoxurus typus) - - 227 Sloth-Bear ( Ursus labiatus] - - - 228 Proboscis- Bear or Coati (Nasua socialis] - 229 Sow and Young of Wild Boar (Sus scrofa] 231 Lower Jaw of Pig (Sus scrofa), showing Teeth • 232 Collared Peccary (Dicotyles torquatus) - 233 Rook (Corvus frugilegus} - - - 236 Brent Geese (Bernicla brentd) - - - 238 Corncrake ( Crex pratensis) ... 240 Crowned Crane (Balearica pavonind) - 241 Skull of Hornbill (Buceros galeatus], in section 242 Lancelet (Amphioxus lanceolatzts], feeding 245 Scrobicularia, with siphons and foot pro- truded ------- 249 House-Fly (Musca domesticd] - - - 252 Common Crayfish (Astacus fluviatilis} - 253 Ship Barnacles (Lepas anatiferd) - - 254 NATURAL HISTORY THE FOOD OF ANIMALS INTRODUCTORY In the early part of Volume I a brief sketch has been given of the process of digestion, by which food is dealt with within the body, and we shall be chiefly concerned in the present section with the various means by which animals obtain the necessary materials wherewith to repair and build up their bodies. Occasion will, however, be taken to recapitulate some of the essential facts and principles relating to the digestive process. It has been cynically remarked that life may be summarized in the conjugation of a single verb — the verb " to eat "-—in its various moods and tenses: — " I eat, thou eatest, he or she eats ", &c., with the terrible converse, " I am eaten, thou art eaten, he or she is eaten", &c. This epigrammatic statement embodies a great deal of truth, for a primary characteristic of living things is the constant necessity for food — the law of hunger. A nugget of gold, or a quartz crystal, may remain for an indefinite time without under- going any appreciable change, and any addition to its substance which may take place consists in the deposition of fresh external layers, such as one sees in the cross-section of a stalactite. But the essential living part of an animal, that exceedingly complex substance known as protoplasm, is extremely unstable, and in- cessantly undergoing waste by a process of breaking down into simpler substances, the simplest of which — as waste products- have to be eliminated from the organism. Every manifestation of life, whether it be a muscular movement the formation of a digestive fluid, a thought, or an emotion, involves and is VOL. II. 1 33 ;Y;;: THE FOOD OF ANIMALS dependent on this sort of waste. In other words, the chemical changes embraced under the term " waste " furnish the power by which the organism is worked, just as a locomotive is kept going by consumption of fuel, or an electric bell made to sound by the chemical action going on in a battery. Yet, despite this incessant chemical disintegration in nearly all parts of its body an animal maintains a constant shape and ap- pearance for long periods of time, or, if young, may exhibit those increases in size and weight which constipate growth. It is therefore evident that waste must be counterbalanced by a corresponding process of renewal, while in such cases as those of a growing child or a fattening ox there is not merely bare renewal, but a formation of new substance, often to a very considerable extent. Increase in size does not, however, consist in the addition of external layers, for the new material must be intimately em- bodied with that already existing. The raw material from which repair and increase are effected is food, which is worked up by the digestive organs into a suitable condition, those parts of it which are not, or cannot be, digested being cast out of the body as useless. One of our most distinguished zoologists (the late Professor Milnes Marshall) describes the chemical changes by which the living substance of the body is constantly being built up and as constantly broken down, in a very picturesque way, and his words may well be quoted here: — "This conception of proto- plasm, or the living matter of animals and plants, as undergoing incessant change, or metabolism as it is called, is one of much importance. Living protoplasm has been compared to a foun- tain in which the form remains constant though each component particle of water is in constant movement. In protoplasm, as in the fountain, we distinguish two main processes, an uphill or anabolic process, as the water rises to the crest of the wave, or the food is being built up into the living tissues; and a downhill or katabolic process, as the water falls from the crest back into the basin, or as the living brain, muscle, &c., become broken down into the various excretory products. The uphill or anabolic processes are synthetic, and require or absorb energy. . . . On the other hand, the downhill or katabolic processes are analytic, and are sources of energy. Protoplasm may, to adopt the simile given above, be regarded as the topmost point, the INTRODUCTORY PROTOPLASM ACTUAL ENERGY WASTE PRODUCTS Fig. 303. — Metabolic Staircase crest of the physiological wave, consisting of matter in a condition of extremely unstable equilibrium ..." (fig. 303). The size, shape, and structure of animals, their habits and distribution, all very largely depend upon the ever-present necessity for food, which indicates its existence by the cravings of hunger and thirst. And it is in the main the radical difference as to food which brings about the striking contrasts in form, structure, and mode of life between animals and plants, especially ordinary green plants, as distinguished from fungi. The food of such green plants is of the simplest kind, consisting, as it does, of the carbonic acid gas of the air, and the water which every- where permeates the soil and holds mineral salts in solution. A plant is therefore surrounded by its proper food, and has only to stretch roots downwards and leafy stems upwards to obtain it in abundance; for which purpose a branching form, offering a large absorptive surface, is eminently suitable. Nor is a digestive cavity necessary to deal with liquid and gaseous food, so such a cavity is characteristically absent. Since, too, the food is in such near proximity, locomotor powers would be superfluous; and equally unnecessary is a well-developed nervous system to regulate loco- motion and, with the aid of special sense organs, place the organism in touch with the outer world. As regards any one of the higher animals the case is far different. " A solution of smelling-salts in water, with an infinitesimal proportion of some other saline matters, contains all the elementary bodies which enter into the composition of protoplasm; but, as I need hardly say, a hogshead of that fluid would not keep a hungry man from starving, nor would it save any animal whatever from a like fate" (Huxley). Being devoid of the green colouring matter called chlorophyll, which enables a green plant to use the energy of the sun's rays for building up simple food into complex substances, the animal has to live upon very elaborate food, which can only be obtained from one of two sources, i.e. plants or other animals. A broad popular distinction has therefore been drawn between flesh-eating animals, plant- eating animals, and those omnivorous forms which, like ourselves 4 THE FOOD OF ANIMALS and the pig, affect a mixed diet. A higher animal possesses many characters related to the nature of its food, and contrasting strongly with the relative features of higher plants, as enumerated above. Such are, in particular, a compact shape, an internal digestive cavity, powers of locomotion, and well-developed nervous system with related sense organs. It will not be uninteresting to consider flesh-eating, plant- eating, and omnivorous animals successively, with special refer- ence to the ways in which they are modified as a result of their proclivities in the matter of food. After this we will briefly review some of the innumerable devices and structural modifica- tions which help animals to escape from those predaceous forms which have developed a gastronomic liking for them. CHAPTER I THE FOOD OF ANIMALS— FLESH-EATING MAMMALS (CARNIVORA)— WHALES (CETACEA) So well marked are the flesh-eating propensities of a large and familiar order of Mammals that they have been christened, par excellence, the " Carnivora ". Here are included a number of important sub-groups, familiarly exemplified by the Cat, Dog, Bear, and Seal. In many of these forms, however, the diet is not exclusively of animal nature, and some of them take a con- siderable quantity of vegetable food. Polar Bears in the Zoo are regularly supplied with green meat as an alterative to theii fish diet, wrhile loaves of bread are served out to Brown Bears, and every child knows that these ordinary Bruins are particularly fond of honey. CAT FAMILY The " harmless necessary cat " is about as typical a Carni- vore as can readily be found, and anyone who has observed the stealthy way in which one of these animals approaches small birds, taking advantage of the smallest cover and closing pro- ceedings with a sudden spring, has a very good idea of the way in which Lions, Tigers, and Leopards hunt down their prey. One would expect a Lion, the symbol of British dignity, to adopt tactics of a more open kind, but, as a matter of fact, this does not appear to be the case. As one wrould anticipate, the muscular system of a Carnivore is exceedingly well developed, the Tiger in particular being very well endowed in this respect, and able to drag along an animal far exceeding him in weight. The feet and teeth of a Cat will repay close examination, since they are specially modified in accordance with the preda- ceous habit. To begin with, the animal does not walk on the soles of its feet as we do, but progresses noiselessly on tiptoe, 6 THE FOOD OF ANIMALS or, to speak more learnedly, is digitigrade (fig. 304). The sharp claws which arm these digits are obviously related to the capture of other animals. To be efficient, however, these weapons must be kept sharp, and hence, when not in use, they are drawn back or retracted into special sheaths, being smartly thrust out when the animal strikes its prey. They are kept sharp by scratching against the bark of trees or any handy table-leg. Like our own nails, to which indeed they correspond, they grow continuously throughout life. ^T^^ The teeth are still more interest- Fig. 304. -Digit of cat ing, and are specialized in a very extraordinary manner. To understand the way in which they are adapted to a special purpose, the best plan will perhaps be to first consider the arrangement of our own teeth (see vol. i, p. 35). A com- plete set of human second or permanent teeth consists of thirty- two members, eight cutting or incisor teeth in front, four pointed canines or eye-teeth, and twenty grinders or cheek-teeth. The number and arrangement may conveniently be expressed by what is called a dental formula^ as follows : — Incisors = - — , canines = - — , grinders = - ~ (consisting of 2 2 1 7 \ premolars = - - , and molars = - — = ) . 2-2' 3-3/ Each fraction represents one kind of tooth, the numerator indi- cating those of the upper jaw and the denominator those of the lower. The dashes divide the right-hand teeth from the left- hand ones, the numbers in all cases corresponding, as the teeth are symmetrically disposed. The cheek-teeth are placed under two headings, premolars and molars, which are much alike in general characteristics, though in the human subject each premolar has two rounded projections or cusps on its crown, and is therefore often called a bicuspid, while each of the molars has four cusps. The essential difference, however, between these two kinds of teeth is that premolars have predecessors among the temporary or milk teeth, while the molars have not. FLESH-EATING MAMMALS 7 The dental formula of the Cat is as follows (fig. 305):— T. 2-2 . I-I t — "I I — I Incisors = - — , canines = - — , premolars = ^ — * , molars = - - . 2-2 I-l' 2-2 I-I It will be seen that the total number of teeth is thirty, two less than in Man, and that there are more above than below. The eight incisors, being small and pointed, are of comparatively little use in dividing food, but the four canines are large pointed tusks, emi- nently adapted for seizing and holding living prey, while the cheek-teeth have sharp cutting edges quite unfit for grinding, but very well suited for dividing flesh. This is especially true f i fc , jf J . , Fig. 305. -Skull of Cat for what are known as the carnassial teeth, which are the much-enlarged first lower molars and last upper premolars (i.e. the third cheek-teeth above and below, counting from the front). These work against one another like the blades of a pair of scissors. It is also to be noticed that the Cat's lower jaw is united to the skull by a very perfect hinge-joint, which only allows of up-and-down movements without any lateral play. The jaws of a Carnivore consequently form a very perfect ap- paratus for seizing prey and afterwards dividing up its flesh by a series of snaps. Other noteworthy features are the small spiny projections with which the tongue is covered, converting it into a very efficient rasp of great use in cleaning fragments of meat from bones, and the comparative shortness of the digestive tube, in striking contrast with what obtains in a vegetable feeder. Plant food, in fact, is harder to digest than meat, and a very large surface is necessary by which the digested matters can be absorbed into the blood and lymph systems. What is true for a Cat as regards structure is in the main true for all cat-like Carnivores, such as Lions, Leopards, Tigers, and Jaguars. As a general rule, too, these animals are coloured in such a way that they harmonize with their surroundings, and are therefore better able to steal upon their victims without being observed (fig. 306). This kind of coloration is of the kind termed by naturalists general aggressive resemblance, which is seen in many groups of widely -differing animals. The conspicuous black and tawny stripes of a Tiger (Felis tigris] do not at first Fig. 306. -Markings of Cat-like Animals , Tiger; 2, Lioness; 3, Panther; 4, Jaguar; 5, Ocelot; 6, Pampas Cat. FLESH-EATING MAMMALS 9 sight appear to favour concealment, but those who have seen the animal among the reeds and grasses of his native jungle, where patches of light and snade alternate in a confused way, assure us that such is the case. The tawny colour of the Lion (Felis leo) of the Old World, and of the American "lion" or Puma (Felis concolor) (fig. 307), Fig. 307. — Puma (Felis concolor] is also an example of aggressive coloration, harmonizing with the sandy wastes that are more particularly affected by these animals. A similar coloration is characteristic of desert forms belonging to widely diverse groups, though in many cases pro- tection is the object sought. It is a curious fact that Lion and Puma cubs differ greatly in colouring from the adults, for the former are striped and the latter spotted. From this it may reasonably be inferred that these uniformly coloured species are descended from striped and spotted forms, and if this inference be correct it is a good example of the " recapitulation " of the history of the species in the life-history of the individual. io THE FOOD OF ANIMALS There are many points in the habits of the Puma which are of especial interest. One of them is its reluctance, even when hunted down, to attack man. W. H. Hudson, in his charming book The Naturalist in La Plata, writes as follows in this con- nection:— " It does not attack man, and Azara is perfectly correct when he affirms that it never hurts, or threatens to hurt, man or child, even when it finds them sleeping. This, however, is not a full statement of the facts; the Puma will not even defend itself against man." In spite of this apparent timidity, however, the Puma is a hunter of no mean capacity, and attacks large animals in preference to small. Horseflesh is a particularly favourite article of diet, and introduced horses maintain them- selves with such extreme difficulty in the puma-haunted regions of America, that Hudson thinks this throws some light upon the remarkable fact that the wild horses, which were once so common on the American continent as indigenous forms, all became extinct despite the favourable conditions as regards food and climate. The Puma is further of interest as being an example of an animal possessing a wide geographical range, in this case practically the whole of America, and its habits vary according to the nature of the surroundings. For the most part it pursues animals which live upon the ground, but in the forest regions of South America has been seen chasing monkeys among the trees. While the largest of the Cat Family, i.e. the Lion and Tiger, either do not climb at all, or do so to a very small extent, and the Puma is not a thorough -going climber, there are a large number of allied species both large and small which largely ex- tend their sphere of operations by the assumption of a climbing habit. Here are included such forms as the Jaguars of the New World, and the Leopards, Lynxes, and Small Cats of the Old. In all these cases the fur is more or less spotted or mottled in such a way as to harmonize with foliage, and render the animals inconspicuous (fig. 306). All the members of the Cat Family so far mentioned, when attacking prey possessed of great powers of speed, mainly rely upon a stealthy approach terminating in a sudden rush or spring ; but the Cheetahs or Hitnting Leopards (fig. 308) pursue different tactics. It is true that these long-legged creatures approach to within a reasonable distance of such animals as antelopes or deer by stalking them, but so fleet are they them- LION SEIZING PREY Members of the Cat tribe, both small and large, hunt their prey in the same kind of way. First there is a stealthy approach, and last a sudden spring, which commonly secures a victim. The plate represents this final stage in the case of a lion which has been stalking a herd of Sable Antelopes. The so-called "king of beasts " is enormously strong, and literally hurls himself upon his prey, preferring the neck as the point of attack. The first blow of the paws often shatters the cervical vertebrse. causing instant death. O FLESH-EATING MAMMALS n selves that if the first rush should fail they are often able to run down their prey. Cheetahs, indeed, are the greyhounds among the Cats, if such an expression is permissible, and it has been asserted that they hold the record among Mammals for short- distance running. Most members of the Cat Family subsist chiefly or entirely upon land animals. It is, however, a matter of common know- Fig. 308. — Cheetah or Hunting Leopard (Cyncelurus jubatits) ledge that domesticated grimalkins are particularly fond of fish, and have even been known to acquire the habit of catching these for themselves. And the large spotted Fishing Cat (Felts viver- rina) of India and South China largely depends upon this kind of food. CIVET-CAT FAMILY The Viverrine or Civet-like Carnivores get their living much in the same way as the Cats proper, but, being smaller, attack prey of corresponding size. For this pursuit their long slender bodies, with comparatively short legs and narrow snouts, are well adapted. Viverrines include a large number of widely differing forms, all of which, however, are less specialized than the Felidae, as seen more particularly in the fact that their teeth are more numerous and less formidable, while their claws are in most cases 12 THE FOOD OF ANIMALS comparatively weak. The largest member of the group, and at the same time the least typical, is the Foussa (Cryptoprocta ferox), a form peculiar to Madagascar, and probably to be looked on as being a connecting-link with the Felidae (fig. 309). All the Mas- carene Carnivores belong to the Civet group, and by far the most formidable of these is the animal in question. In appearance it Fig. 309. — Foussa (Cryptoprocta ferox) suggests a cat of slender proportions, and may attain a length of about 5 feet, of which, however, nearly half is taken up by the tail. Little is known of its habits, but it is extremely ferocious, and much dreaded by the natives. Like cats and the like, it is able to pursue prey both on the ground and among the trees. The Civets proper and their immediate allies are characteristic of the warmer parts of the Old World, and some of them are far from being entirely carnivorous in diet. We find here, as among the Felidae, some species possessed of marked climbing powers, as in the case of the Asiatic Palm- Civets, or Toddy- Cats (Paradox^tres\ the favourite food of which consists of birds, eggs, and small quad- rupeds such as rats and lizards. The name of Toddy-Cat has FLESH-EATING MAMMALS 13 reference to an almost human frailty displayed by some of these animals. In Ceylon and the south of India the natives are in the habit of suspending vessels from palm-trees in order to collect their sap, which, when fermented, is known as " toddy ". Palm- Civets are particularly prone to help themselves to this beverage, with the usual results. The arboreal Binturong or Bear-Cat (Arctictis] of North India and South-east Asia, closely related to the Palm-Civets, is of special interest, for its powers of climb- ing are considerably enhanced by the possession of a grasping or prehensile tail. All the Viverrines so far mentioned pursue their prey either on the ground or among trees, but fishes and other inhabitants Fig. 310. — Mampalon (Cynogale Bennetti] of lakes and rivers are not exempted from the attacks of animals belonging to this rapacious family. An interesting case is afforded by the Mampalon (Cynogale) of Borneo and Sumatra, an otter- like creature with sharply-pointed teeth and partially webbed feet (fig. 310). An expert swimmer, its food chiefly consists of fishes and other aquatic forms, but its resources appear to be consider- able, for it is said to climb well, and birds must be added to its extensive dietary, which is also believed to include fruit. The Mangoustis include those Viverrines which are most unlike the Felidae, and the most familiar species are those char- acteristic of Egypt and India. Their food consists mainly of small four-footed animals, birds, and snakes, and though they are I4 THE FOOD OF ANIMALS susceptible to the poison of the last-named animals, their extra- ordinary activity generally saves them from being bitten. Allusion has elsewhere been made to their fabled knowledge of vegetable antidotes to snake-bite, which rests upon no foundation in fact. The Crab - eating Mangousti (Herpestes urva] of South - east India, Further India, and South China, is said to be semi-aquatic, and to feed upon frogs and crabs. HY.ENA FAMILY. The Carnivores so far dealt with prey upon living animals, but nothing is wasted in nature, and scavengers are needed to Fig. 311. — Spotted or Laughing Hyaena (Hycena crocuta] deal with carrion. To this category belong the unsavoury Hyaenas (fig. 311), though they also attack the more defenceless mammals. Their specialized teeth are eminently adapted to a carnivorous diet, and with this specialization goes a reduction in number, as in the Cat Family, though in this case the reduction has not gone quite so far, there being thirty-four teeth as against thirty in the latter family. So powerful are the jaws of Hyaenas that they can negotiate skeletons which have been picked clean by other animals, and swallow large quantities of bone in order FLESH-EATING MAMMALS 15 to extract the nutriment from it. Regarding this propensity Sir Samuel Baker remarks (in Wild Beasts and Their Ways): "The bone -cracking power of this animal is very extraordinary. I cannot say that it exceeds the lion and tiger in strength of jaws, but I can safely assert that both those giants of the feline tribe will leave bones unbroken which a hyaena will bite in halves. Its powers of digestion are unlimited; it will swallow a large knuckle-bone without giving it a crunch. It will crack the thigh- bone of a wild buffalo to obtain the marrow, and will swallow either end immediately after." The Earth-Wolf or Aardwolf (Proteles) of South Africa is a very interesting example of a specialized hyaena which has taken to burrowing (see vol. i, p. 92). The teeth of adult specimens are of peculiar character, for the cheek-teeth are all much alike, and separated by wide intervals. Their crowns are small and pointed, in adaptation to the food, which is said to consist largely of white ants, though no doubt carrion and various small creatures also form part of the diet. The late Mr. A. D. Bartlett, for many years Superintendent of the Zoological Gardens in Regent's Park, after an earth -wolf "had refused pigeon, rabbit, beef, mutton, boiled and raw and chopped in a sausage -machine, and bread - and-milk", at last succeeded in feeding it on "nice fat tripe, well boiled in milk ", which suggests that the creature's natural food is of a savoury nature. The study of the first or milk-teeth of the Earth- Wolf brings to light a most interesting case of the Law of Recapitulation (see pp. 9 and 29), for here we find a clear distinction between premolars and molars, while shear-like flesh- teeth or carnassials are present. This and other anatomical facts clearly prove that these animals are descended from forms which resembled ordinary hyaenas in structure and habits. DOG FAMILY This section of the Carnivora, which includes Dogs, Wolves, Jackals, Foxes, and the like, best represents the average features of the order. The structure of these forms is clearly adapted to the flesh-eating habit, but their teeth and claws are not specialized as weapons of offence to the same extent as the corresponding organs of the Felidae. Thus the canine and carnassial teeth are well-marked (fig. 312), but not so prominent as in cat-like forms, i6 THE FOOD OF ANIMALS Fig. 312. — i, Jaws of Dog. mt Molars ; pm, Premolars ; cl, Carnassial ; can, Canines; i, Incisors. 2, Skull of Thylacinus. Note in fig. 3 (representing the front-teeth of Thylacinus) the four incisors in the upper, and three in the lower jaw. and the blunt claws are not capable of being drawn back into sheaths. As might be expected, the teeth are more numerous than in the latter group, their total being generally forty-two as against thirty. Although some of the dog-like animals are carrion- eaters to a greater or less extent, the pursuit of living prey is the rule, and the actions, of dogs in a fox-hunt exemplify, under artificial conditions,, the normal condi- tion of such ani- mals in a state of nature. That is to say, a number of individuals co-op- erate together, and the quarry is tracked, mainly if not entirely, by means of the sense of smell. All sorts of Wild Dogs, Wolves, and Jackals hunt together in packs, trusting mainly to their noses, and everyone will recall instances of the kind related in books where the Wolf plays a conspicuous part in the narrative. W. P. Lett (in a section of The Big Game of North America) gives the following very good example of the clever tactics pursued by wolves: — "The Madawaska River, which was once, so far as unrivalled natural beauty could make it so, the rushing, foaming queen of Ottawa's peerless tributaries, has along its turbulent course many rapids and chutes of wondrous grandeur and beauty. One of those chutes, about one hundred miles from the city of Ottawa, is called the Wolf Portage. It was so named on account of the wolves chasing deer into the water at that point during winter. The hunted deer were in the habit of rushing into the rapids to escape the fangs of their sanguinary pursuers. In catching the deer at the Wolf Portage, the wolves displayed much cunning. When a deer took to water at the head, it was quickly carried over the rough chute and down the rapids into* the gradually narrowing, ice-enclosed glade or channel at the foot. Just at the spot where the current drove it against the ice, under which it would immediately be whirled, a number of the wolves stood on the ice, and the instant the deer touched its edge it was seized by the fierce and hungry animals, dragged out upon the ice,, A PACK OF WOLVES HUNTING The Common Wolf (Cants lupus) ranges over the cold and temperate parts of the northern hemisphere, and was formerly abundant in Britain — the last surviving Scottish individuals being killed in 1743, and the last Irish ones even later (? about 1770)- The wolves of England are said to have been finally exterminated during the reign of Henry VII. During winter these rapacious carnivores associate themselves into packs, and hunt their prey systematically during the night. These aggressive proceedings are carried out with that kind of skilled division of labour which is characteristic of many social animals. And as in nocturnal flesh-eaters generally, the sense of smell is very strongly developed, constituting the chief means by which prey is tracked. ' A PACK OF WOLVES (CANIS LUPUS) DRAWN FROM THE LIFE BY F. SPECHT FLESH-EATING MAMMALS 17 and devoured. In the early lumbering days upon the Madawaska the skeletons of deer could always be seen in winter lying on the ice at the foot of the Wolf Portage." Foxes differ in many ways from the other members of the Dog section, hunting, for example, "on their own", and not in packs. Another well-known peculiarity is the habit of living in burrows which have either been excavated by the animals themselves or else are the appropriated homes of other species, such, for example, Fig. 313. — Vizcacha (Lagostomus trichodactylw} in this country, as the badger. Cases are also known where foxes share the tenancy with the original proprietors, not always to the advantage of the latter, as the following example will show. The commonest mammal of the South American pampas is the burrowing rodent called the Vizcacha (Lagostomus trichodactylus) (fig. 313), which lives in large communities known as vizcacheras. A kind of fox, the Aguarachay (Canis Azarcz), inhabits the same regions, and his behaviour towards the Vizcacha is best described by quoting the graphic account given by W. H. Hudson (The Naturalist in La Plata)'. — "The fox takes up his residence in a vizcachera, and succeeds, after some quarrelling (manifested in snarls, growls, and other subterranean warlike sounds), in eject- ing the rightful owners of one of the burrows, which forthwith VOL. ii. 34 18 THE FOOD OF ANIMALS becomes his. Certainly the vizcachas are not much injured by being compelled to relinquish the use of one of their kennels for a season or permanently, for, if the locality suits him, the fox remains with them always. Soon they grow accustomed to the unwelcome stranger; he is quiet and unassuming in demeanour, and often in the evening sits on the mound in their company, until they regard him with the same indifference as they do the burrowing owl. But in spring, when the young vizcachas are large enough to leave their cells, then the fox makes them his prey; and if it is a bitch-fox, with a family of eight or nine young to provide for, she will grow so bold as to hunt the helpless Fig. 314.— The White or Arctic Fox (Cam's lagopus] • quarry from hole to hole, and do battle with the old ones, and carry off the young in spite of them, so that all the young animals in the village are eventually destroyed." Foxes furnish good examples of coloration which harmonize with the surroundings, and in this case serve a double purpose, rendering the animals inconspicuous both to their enemies and to their prey, illustrating, therefore, to speak technically, both protective general resemblance and aggressive general resemblance. The Arctic Fox (Cams lagopus] (fig. 314), presents this peculiarity in a way which is not infrequent among the inhabitants of the colder parts of the globe, varying in colour according to the season. In summer it is of a gray-brown hue, with a bluish FLESH-EATING MAMMALS 19 sheen, which explains the term "blue fox" so often met with in accounts of polar voyages, while in winter it is of a snowy-white. Desert animals make an approach to the desired end of invisi- bility by means of a uniform fawn or buff colour, and this is the case with the little Fennec (Cants zerda), a long-eared fox in- habiting the Sahara (see vol. i, p. 93). BEAR FAMILY, &c. The last great section of the terrestrial Carnivora is the one which includes Bears and many allied forms. Bears are for the most part very mixed feeders, but the Polar Bear (Ursus arctos), which is the largest of them, is essentially a flesh-eater, though it devours vegetable matter to some extent, when such is available. This huge creature is the biggest living Carnivore, and old males have been known to attain a length of over 8 feet and a weight of some 900 pounds. To maintain so vast a bulk means an enor- mous quantity of food, regarding which Sergeant Francis Long of the Greely Arctic Expedition remarks (in The Big Game of North America): — " About four hours each day is the longest time he allows himself for rest from his patient and persevering search for food, for his cavernous maw and his voracious appetite tax his skill and time to keep them supplied with fish and flesh. In his hunt for game the night as well as day is favourable to him, the reflection from the ice at night being sufficient light to enable him to sight and steal upon his prey. The seal is the chief source of food for the Polar Bear, though he also preys upon the walrus and on various fishes." Unlike the Arctic Fox, the Polar Bear is always white or yellowish white, and indeed a change of colour is unnecessary, for he spends his whole time surrounded by snow and ice. This must be looked upon as a case of aggressive general coloration pure and simple, for, ex- cepting man, this monarch of the Arctic regions has no enemies capable of injuring him. In stalking such wary creatures as seals, the inconspicuousness due to the white coloration is invaluable, and the Bear is also greatly helped in this pursuit by the fact that the under sides of his feet are thickly covered with fur, which not only prevents slipping, but also conduces to noiselessness. Marked powers of swimming and diving confer additional advantages. Many accounts have been given of the cunning with which this 20 THE FOOD OF ANIMALS animal hunts his chief victim, the seal, and the following quo- tation from S. M'Tavish (in The Big Game of North America) will serve as a typical example: — "Their modus operandi of catching the seal is as follows: — The bear having discovered a seal asleep on an ice-floe immediately slips into the water if he himself be on another ice-floe, Alternately diving and swimming, he approaches close to his victim. Before his final disappearance he seems to measure the intervening distance, and when he next appears it is alongside of the seal. Thefi, either getting on the ice or pouncing upon the seal as it tries to escape, he secures it.'" Those who wish a graphic account of the Polar Bear at home should peruse Nansen's Farthest North, though this will be superfluous advice for most readers. Passing by the Raccoons and other Small Bears, which are for the most part as omnivorous as the majority of their larger relatives, the last group of allied terrestrial Carnivores to demand attention is that of the Weasels, which are among the most blood- thirsty animals in existence. The largest species, and one which approaches the Bears in many points, is the Glutton or Wolverene (Gulo luscus), an inhabitant of the northerly parts of both Old and New Worlds. The scientific name of this creature is a very good example of the absurdities often involved in such terms. The generic appellation, Gitlo (Lat. glutton), is not very happy, and distinctly slanderous, for though the animal is decidedly voracious it has no claim to be picked out as a type and emblem of excess in the pleasures of the table, though the old zoologists, thought so, and promulgated some extraordinary stories on this head, some of which betray a lively though somewhat coarse imagination. But the specific name, luscus (Lat. one-eyed], is absurd in the extreme, and was given because the first described specimen had accidentally lost an optic. The Glutton is a noted destroyer of many sorts of game, and has even been known to attack reindeer. Significant testimony to his destructive powers is found in the fact that in Norway the same government premium (i.e. 20 kroner = about £\, 2s. 6d.) is paid for his carcass as for that of a bear or wolf. He can both climb and swim, and has a well- earned reputation for cunning, his talents in that direction causing great annoyance to the North American trappers, whose traps he systematically robs. The depredations of the Glutton are much aided by his dull-brown colour and stealthy nocturnal habits> THE POLAR BEAR (Ursus arctos] The Polar Bear is one of the most rapacious of the flesh- eating mammals, its food consisting largely of seals. These are often captured as the result of combined cunning and patience, the bear waiting for them at the holes in the ice where they rise to breathe. Great powers of swimming and diving largely help in the pursuit of this kind of prey, as also of fishes. The Polar Bear is remarkable in being always white, or yellowish-white, in colour, being thus rendered inconspicuous among its surroundings of ice and snow. This is a good instance of General Aggressive Coloration, whereby an animal which harmonizes with the hue of its surroundings is enabled to approach its prey without exciting premature suspicion. CO -j ID CO tU I. ? o: 1 CD Q o: te o Q. UJ X h- FLESH-EATING MAMMALS 21 all of which help to secure inconspicuousness. Chapman, in Wild Norway, writes: — ". . . One may easily spend years in the haunts of the Glutton without obtaining (in summer) so much as one glimpse of the beast; for he is strictly nocturnal and of secretive habit, lying up all day in the wildest and most rugged corries and rocky glens. I have never myself met with the least evidence •of his existence, though hunting forests where we knew him to be." BADGER, WEASEL, AND OTTER FAMILY The most typical members of the present family are the Weasels, Stoats, Sables, Polecats, and their allies. The Common Weasel (Mustela vulgaris) is an abundant British mammal, the Fig. 315. — Stoats (Mttstela erminea] in summer dress extreme alertness of which has become proverbial. It relentlessly pursues all manner of small animals, which vainly seek shelter in narrow crannies or convenient crevices, for their enemy's long neck and narrow sinuous body, with short limbs (see vol. i, p. 97), •enable him to follow almost anywhere, while the quarry is rarely his match in point of speed. Added to this, the Weasel is a •good climber, so that brooding birds, nestlings, and eggs form an important item in his bill of fare. A number of these animals often hunt together, co-operating with much intelligence for a 22 THE FOOD OF ANIMALS common end. Our native Polecat (Mustela putorius) is practically a large and relatively clumsy Weasel, which aims at larger game, while the Martens, such as the Pine Marten (Mustela martes], a British species, may be looked upon as arboreal Weasels, though they also hunt upon the ground. Mention may be also made of the Stoat or Ermine {Mustela erminea) (figs. 315 and 316), the Fig. 316. — Stoats (Mustela erminea) in winter dress characters of which are well expressed by one of its common names, that of " greater weasel ". This is one of the forms which change their coats at different times of the year, the winter fur, commonly known as "ermine", being white except for the tip of the tail, which remains jet black. In this way the Stoat is rendered inconspicuous to its prey both in summer and winter. The Minks of North America, Europe, and Siberia are best described by calling them Water - Polecats, fitted for a semi- aquatic life by the possession of dense fur, small ears, and partly webbed feet. They feed on fish, water-birds, and the like, but also range over the ground which adjoins the banks of their native rivers. From them we naturally pass to the Otters, which form a thorough-going aquatic group of the weasel family. The Common Otter (Lutra vulgaris) (fig. 317) is too well known to need much description, and it need only to be noted that its shape FLESH-EATING MAMMALS 23 and structure are eminently adapted to the pursuit and capture of fish, which constitute its main food. The flattened head and spindle-shaped body, continued into a gradually tapering tail, flattened from side to side, offer as little resistance as possible to swift passage through the water, and friction is further reduced by the dense smooth fur. The feet are completely webbed, and Fig. 317.— Otter (Lutra vuigaris) are largely assisted in their work of propulsion by the powerful tail. The slippery prey, once overtaken, has no chance of wriggling away from between the slender backwardly - curved canines and the sharply-curved teeth by which these are succeeded. Having secured his fish, the Otter holds it between his fore-paws and beginning at the head eats steadily backwards, that is, if really hungry; but in many cases this animal appears to merely hunt for the pleasure of it, and is content with a single bite just behind the back of the fish's head. A small South American species, the Feline Otter (Lutra felina\ affects a marine habit, and haunts the fjords which abound on the western side of that region. This prepares us for the existence of a thoroughly marine species, the Sea Otter (Latax lutris], a large form inhabiting the North Pacific coasts, and attaining the length of 3 feet 24 THE FOOD OF ANIMALS exclusive of the tail. This creature looks as if it were on the way to become a sea-lion, especially in the appearance of its head and flipper-like hind-limbs. Its food differs entirely from that of ordinary Otters, as the blunt crushing back -teeth suggest, regarding which H. W. Elliott writes (in An Arctic Province]: — " Instead of being a fish-eater . . . it feeds almost wholly upon clams, crabs, mussels, and echinoderms or 'sea-urchins', as might be inferred from its peculiar flat molars ..." We have now passed in review the most important types of the purely flesh-eating forms of the Terrestrial Carnivores or FISSIPEDIA, and gained -some idea of their food and manner of feeding. Before leaving them, a remark is necessary on the powers of sense with which they are endowed. Many of them, as the cat-like forms, have exceedingly acute vision, and their forwardly-directed eyes enable them easily to see prey in front of them. In many cases, too, considerable powers of hearing are possessed, and in order that they may perceive sounds in front of them the ears are usually forwardly directed, for it is well known that the function of the external projection to which the term " ear " is popularly applied has, as its chief function, the determination of the direction from which sounds proceed. Many Carnivores track their prey by means of the sense of smell, and this is particularly true of the dogs and their allies. Otters, too, are exceedingly well endowed in this respect. Nor must the sense of touch be forgotten, to which the characteristic " whiskers " largely minister. These structures are of the greatest use in enabling an animal to perceive the presence of obstacles, and to judge whether a noiseless passage can be made through gaps in undergrowth and the like. Such knowledge is the more important, since the terrestrial Carnivores pursue their prey chiefly during the night, and in many cases even a slight noise would be fatal to success. Several of the animals already mentioned are partly or entirely aquatic in habit, but the members of the second great group of Flesh-eating Mammals, i.e. the Aquatic Carnivores or PINNIPEDIA, are highly specialized for life in the water. They include Seals, Sea- Lions, and Walruses. In all these aquatic Carnivores the body is shaped so as to promote rapid progression through the water (see vol. i, p. 99), and this is especially true of the Seals proper, which approach PORPOISES, DOLPHINS, AND WHALES 25 most nearly to the fish-like form. The limbs, too, are modified into webbed paddles, the hinder pair of which are fairly free in the Sea- Lions and Walruses, but in the Seals are backwardly directed and bound up by skin with the tail so as to form a powerful propeller, eminently adapted for rapid swimming, but quite unsuited for movement on land, so that while a walrus or Fig. 318.— Skulls of Seal (A) and Walrus (B) sea-lion can shuffle along fairly well on the ice, a seal has much greater difficulty in getting along when re- moved from the water. The teeth of these marine Carnivores are in a very interesting condition, having a direct relation to their food. Sea- Lions and Seals live chiefly on fish, and possess numerous sharply- pointed teeth, well adapted for seizing and holding such slippery prey (fig. 318). Walruses mainly subsist on burrowing shell-fish and other creatures living in mud or sand, and they have a pair of long, tusk-like canines in the upper jaw, by which their food can be dug out of the sea-bottom (fig. 318). These tusks continue to grow throughout life, and in accordance with this do not taper into fangs within the jaw, but project far beyond it. The re- maining teeth are blunt and simple, their form fitting them for crushing the food. PORPOISES, DOLPHINS, AND WHALES (CETACEA) The Mammals included in this class have become very much specialized to fit them for an aquatic life, and, although their remote ancestors were undoubtedly terrestrial, they have no very near allies among existing land animals. The body is fish-shaped, and suited for rapid progression through the water, propelled by the powerful tail, which is broadened out horizontally (not verti- cally, as in a fish). The fore-limbs are paddle-like flippers, without external trace of digits, and the hind-limbs are only represented (in 26 THE FOOD OF ANIMALS some forms) by a couple of little bones embedded in the muscles, and not to be seen from the outside. All Cetaceans are carnivorous, and as, in feeding, they are obliged to open their mouths under water, there would be constant danger of choking were there not some special arrangement for preventing water from getting into the lungs. Such a contrivance is here found in the top of the windpipe, which is drawn out into a long cone that fits into the internal opening of the nasal passage. Food can pass back on either side of this«cone to the gullet, while at the same time there is no interference with breathing. Cetaceans are divided as a matter of convenience into Toothed Whales (Odontoceti) and Toothless Whales (Mystacoceti)> which will be considered separately, as their food and way of feeding differ considerably. TOOTHED WHALES (ODONTOCETI) Here are included the Dolphin and Sperm-Whale Families, the members of which vary from 6 to 90 feet in length. DOLPHIN FAMILY (Delphinida). — The most familiar animal belonging to this family is the Porpoise (Phoccena communis] (see Fig. 319.— Killer-Whale (Orca gladiator] vol. i, p. 100), which is about 6 feet in length, with rounded snout, and jaws armed with about one hundred small sharp, pointed teeth. These are well suited to the nature of the food, PORPOISES, DOLPHINS, AND WHALES 27 consisting chiefly of fish, which porpoises not only catch in the open sea, but also pursue into estuaries. The highly predatory Killer- Whale (Orca gladiator) (fig. 319) may be as much as 26 feet long, and resembles in appearance a gigantic porpoise. Its propensities are described by Vogt (in The Natural History of Mammals] in the following words: — "They are the absolute tyrants of the seas, and work fearful Fig. 320.— Dolphin (Delphinus delpkis] slaughter among the seals and among other cetaceans. Eschricht, a Danish anatomist, who has occupied himself with the Cetacea in a very thorough manner, found a seal sticking in the throat of a killer- whale of about 1 6 feet in length, which had owed its death to its voracity, since it was prevented from swallowing this seal by having thirteen porpoises and fourteen seals already engulfed in its stomach! The shoals of killer- whales attack the largest ceta- ceans, and vanquish them. They are said to be peculiarly fond of the fat, fleshy tongues of the whalebone whales." One would rather like to know the collective bulk of the thirteen porpoises and fourteen seals mentioned in the preceding extract. The teeth of the killer- whale are all placed in the front of the mouth, and are forty-four in number. They are of conical shape and backwardly curved. The Common Dolphin (Delphinus delphis) (fig. 320) is rather 28 THE FOOD OF ANIMALS larger than the Porpoise (about 8 feet in length), and its snout is drawn out into a short flat beak. The small sharp teeth are often more numerous than those of the Porpoise (up to 200). The habits of this creature are thus described by Vogt (in the work above quoted): — "This dolphin is the animal celebrated by fabulists and depicted by artists, the friend of man, who carries the singer Arion to the shore, renders aid to the shipwrecked, draws the chariot of Galatea, and carries the Tritons and nymphs of the court of Amphitrite. Unfortunately all these virtues have disappeared under the critical eye of modern observers, who no doubt recognize in the dolphin an agreeable travelling companion, who shortens the idle hours of a long sea-voyage by his graceful sporting round the ship, but who, at the same time, is a terribly voracious ravager, who pursues with fury the fastest swimmers Fig. 321. — Freshwater Dolphin (Platanista Gangetica) among fishes, herrings, mackerel, water-snakes (Pelamides\ and flying-fish, darting about after them with the most rapid and abrupt changes in his course, and hastening up to a mortally wounded comrade, not to render him succour, as the ancients said, but to devour him." Fresh-water Dolphins, feeding entirely on fish, live in the rivers of India (Ganges, Indus) and South America (Amazon, Orinoco), and in these the snout is prolonged into a long narrow beak, armed with small teeth, and admirably adapted for seizing and holding the prey. The species figured (fig. 321) is the Gangetic Dolphin or Susuk (Platanista Gangetica}, which is about 6*/2 feet PORPOISES, DOLPHINS, AND WHALES 29 long, and possesses something like thirty-two sharp conical teeth, curved slightly backwards. Those near the front of the beak are larger than the others. SPERM-WHALE FAMILY (Pkyseterida\ — The largest species here is the gigantic Sperm- Whale or Cachalot (Physeter macro- cephalus], that rivals in size the toothless whales, attaining as it does a length of 90 feet, of which about one -third is taken up by the huge squarish head. No traces of teeth are to be seen in the upper jaw of the adult, but at an early period of existence vestiges of them are found in the substance of the gum, though not visible externally. The lower jaw is armed with numerous (twenty to twenty-five each side) massive conical teeth, which fit into pits in the upper jaw. The food is said to consist entirely of squids and cuttle-fishes, and huge specimens of the sort are probably more numerous in the open sea than is generally imagined. TOOTHLESS OR WHALEBONE WHALES (MYSTACOCETI) This sub-order includes the largest animals now existing on the earth, sperm-whales alone excepted. The longest of them (up to 115 feet) is the Rorqual of the North Atlantic (Bal&noptera boops), but the most familiar species is the Right or Greenland Whale (Bal&na mysticetus), which, though not so long (80 feet), is much more bulky, and may attain a weight of almost 1 50 tons. At a very early stage in its existence teeth begin to form in the jaws of this animal (as indeed in the toothless forms generally), but they never cut the gum, and later on all trace of them is lost. No doubt the ancestral forms from which these whales are de- scended possessed numerous teeth resembling those of dolphins and porpoises, and these useless vestiges are reminiscent of the toothed stage in the history of the sub-order. They afford one of the most striking instances known of the Law of Recapitula- tion, in accordance with which the development of the individual presents an imperfect epitome of the evolution of the species. It is one of the most extraordinary facts in the whole of zoology that these enormous toothless creatures mainly depend upon very minute animals as food. Floating upon the surface of the ocean are vast assemblages (known as "plankton") of small molluscs, crustaceans, &c., and it is these which are the chief diet of the 3° THE FOOD OF ANIMALS Greenland Whale. The teeth have here been superseded in favour of a complex arrangement for catching the diminutive prey, and at the same time for getting rid of the superfluous water. The capture-apparatus consists of some 400 horny plates, composed of the so-called whalebone, which grow down from the roof of the mouth, and are placed in two rows, with their flat surfaces directed to the front and back. The curved inner edge of each plate is frayed out into innu- merable slender fibres, which, with the help of the tongue, constitute a very effective strainer (fig. 322). When a sufficiently large mouthful of food has thus been sepa- rated from the sea-water, it is swallowed, and the straining process recommences. When it is mentioned that a Greenland Fig. 322. — Baleen or Whalebone a, three plates cut through, showing frayed edges; b, a pair of plates seen Whale 6O feet long is furnished with from the front. r 1 i i r 1 • i i some 32 cwt. of whalebone, of which the largest plates are as much as 15 feet long, the huge size of this strainer will be appreciated. THE GREENLAND OR RIGHT WHALE (Balcena mysticetus} Whales, the largest existing animals, are not fishes, as often 'supposed, but mammals which have become highly specialized in relation to an aquatic existence. Hence the fish - shaped body, the paddle-like fore-limbs, and the propulsive tail, which is flattened from above downwards and not, as in a fish, from side to side. The hind-limbs are only represented by insig- nificant vestiges not visible externally. A thick layer of fat •("blubber") is present below the skin, compensating for the practical absence of a hairy external covering. The Greenland Whale, which is the species here depicted, may be over 80 feet long and nearly 150 tons in weight. In spite of its huge size it feeds chiefly upon the shoals of small and minute animals which abound on the surface of the ocean, these being strained through the fringed plates of "whalebone", or baleen, which hang down from the roof of the mouth. Whales rise from time to time to the surface to breathe, a double "blow-hole" on the top of the head representing the nostrils. The "spout" does not consist of water that has passed through the mouth, but is simply the condensed moisture of the breath. The mouth can be kept under water without fear of choking, for the top of the windpipe projects into the back of the nasal passages, and food can pass into the gullet on either side of it. THE GREENLAND OR RIGHT WHALE (BALAENA MYSTICETUS) DRAWN FROM THE LIFE BY F. SPECHT CHAPTER II THE FOOD OF ANIMALS— INSECT-EATING MAMMALS Two orders of Mammals include animals which feed chiefly on insects, i.e. the Insect- Eaters proper (Insectivora) and Bats (Cheiroptera). INSECT-EATERS PROPER (INSECTIVORA) The Insectivores, or Insect- Eaters proper, are Mammals of small or even diminutive size, which abound in all parts of the world except South America and the Australian region, and are adapted for preying upon insects, worms, snails, &c., while the larger species also attack small vertebrates such as frogs and mice. Since food of suitable kind is to be found not only upon the ground, but also within it and among the trees above it, as also in the waters of the land, we might expect to find, as among the Carnivores, burrowing, climbing, and aquatic species, in addi- tion to forms which run or spring, and this is actually the case. As becomes Mammals of small size, pursuing prey of corre- sponding dimensions, the Insectivores are creatures of lowly organization, and their intelligence is small as compared to that of such highly specialized forms as the Carnivores. Their prey being for the most part very active, it is not surprising that they also, as a rule, possess the power of rapid move- ment, and, since they hunt mostly by smell and sight, their pointed heads are often produced into a long sensi- tive snout provided with tactile hairS, Fig. 323.-Skull of an Insect-eating Mammal I*., .1 . . (Hedgehog) and bearing the nostrils at its tip. On the other hand, both eyes and ears are often small, and some- times extremely so. Most of the species do their hunting at night. The numerous teeth (fig. 323) differ strikingly in character from 31 32 THE FOOD OF ANIMALS those of the Carnivora, exhibiting no prominent tusks or scissor- like carnassials. Both incisors and canines are small and pointed, while the crowns of the cheek-teeth are studded with sharp cusps. Taken as a whole the teeth form a very effective trap for insects and the like. The Common Hedgehog (Erinaceus Europeans] (fig. 324) is a good type of the larger and more sluggish species. Its snout is unusually short for an Insec- tivore, and its diet is somewhat Fig. 324. — Hedgehog (Erinaceus Euro/xzus} and Young. A rolled-up individual is shown on the right. mixed, including not only insects, worms, and other invertebrates, but also frogs, snakes, eggs, small birds, mice, and fruit. Re- garding its ability as a mouser Carl Vogt speaks as follows: — "The movements of the Hedgehogs are sluggish, their steps almost tottering, their gait clumsy but noiseless; yet, in spite of this ap- parent clumsiness and helplessness, the hedgehog is perhaps even better fitted for hunting mice than the cat. It patiently lies in wait for the nimble rodent at the entrance of its hole, and even shows some skill in reaching its prey by burrowing. The noise which it makes in barns, cellars, and stables perhaps helps to drive away the mice; so much, at least, is certain, that places visited by hedgehogs are soon freed from rats and mice and all their kindred." A remarkable peculiarity of the Hedgehog is its im- INSECT-EATING MAMMALS 33 munity against animal poisons, being quite unharmed, for example, by the bite of an adder. It is believed to know the difference between poisonous and harmless snakes, for in tackling the former it always begins with the head. The Tenrecs of Madagascar are relatives of the hedgehogs, but have longer snouts, and present all degrees of spininess down to the entire absence of prickly structures. They are, moreover, of very various size. One of the largest is the Common Tenrec Fig. 325. — Common Tenrec (Centetes ecaudatus) {Centetes ecaudatus} (fig. 325), while the small Rice-Tenrecs (Oryzorictes) are specially interesting on account of their mole- like form and habits. It is a remarkable fact that the nearest relatives of the Tenrecs are the Agoutas (Solenodon) of Cuba and Hayti. In these both snout and tail are much elongated, and the digits are armed with powerful claws. Although little is known of their habits, it is believed that they subsist entirely upon animal food. The Golden Moles (Chrysochloris) (fig. 326) of South Africa, so named on account of their iridescent fur, appear to find their nearest relatives in the Tenrecs, and not in the ordinary moles, as would be naturally imagined. Just as specialization for an aquatic life takes place on similar lines in a number of different groups, so also in the case of burrowing Mammals adapted for the pursuit of earthworms. One marked difference between VOL. II. 35 34 THE FOOD OF ANIMALS a Golden Mole and an ordinary mole is found in the structure of the fore-limb, modified in both cases for digging. In the former there are but three digits, all armed with powerful claws; Fig. 326. — Golden Mole (Chrysochloris) while in the latter there are five digits, similarly provided, and the general appearance is hand-like. The Shrews include the smallest, most typical, and most widely distributed members of the order. They are exceedingly active creatures, and the more typical species, such as the Garden- Shrew (Crocidura aranea) (fig. 327), hunt chiefly on the ground, though they are also able to climb. Burrowing Shrews (Anuro- sorex) have been described from Central Asia and Assam, resembling miniature moles in appearance, and probably with similar habits. A number of Shrews are also more or less modified for an aquatic life, and these exhibit a series of increas- ing specializations. The Water -Shrew (Crossopus fodiens] of Great Britain is a small-eared species which, though not web- footed, is helped in swimming by stiff hairs which project from the under-side of the tail and lower surfaces of the feet. The Swimming-Shrews (Chimarrogale) of the Himalayas and Borneo are distinguished by very similar characters. A large amount INSECT-EATING MAMMALS 35 of adaptation to an aquatic life has taken place in the Web-footed Shrew (Nectogale] of Thibet, where the feet are webbed, and the external ear-flap is entirely absent. The laterally-flattened tail is a powerful aid to swimming. These do not exhaust the list of aquatic Insectivores, though the others to be mentioned do not belong to the family of Shrews. They are the Desmans (Myogale), which are in- cluded in the Mole Fa- mily; and the African River -Shrew (Potamo- gale\ which is the type of a special family. The Desmans are remarkable web - footed forms, in which the snout is in the form of an elon- gated sensitive proboscis used for grubbing about in holes and corners which harbour insect-larvae and other small creatures. The well- developed swimming tail is long, scaly, and flattened from side to side. One species, the Russian Desman (Myogale moschata), which inhabits South-east Russia, attains the length of 16 inches. A smaller species, in which the tail is not flattened, is found in the streams of the Pyrenees. The African River -Shrew {Potamogale velox], an inhabitant of the West African rivers, finds its nearest relatives in the Tenrecs, and may be looked upon as the otter of the Insectivores. It is a large form, reaching a length of 22 inches, of which about half is formed by the powerful laterally -flattened tail, by means of which it is enabled to swim with great rapidity. Not unlike a small otter in appearance, it resembles that animal in regard to its food, which consists of fish. Some unfamiliar burrowing Insectivores have already been mentioned; the Moles proper and their allies may now be noticed. Certain small species of the Mole Family which have affinities with the Shrews are called on that account Mole-Shrews. The Fig. 327. — Garden-Shrew (Crocidura aranea) THE FOOD OF ANIMALS most typical of these (Urotrichus] are found in Japan and North America (fig. 328). These resemble moles more than shrews, but the reverse is the case with a species (Uropsilus soricipes) Fig. 328.— Hairy-tailed Mole-Shrew (Urotrichus) found in Thibet. The Common Mole (Talpa Enropcza) (fig. 329) is a very good instance of an animal which has taken to under- ground life, and has become modified in accordance with its p^f^^/te^ Fig. 329. — Common Mole (Talpa EuropcEa) habits. The limbs are converted into powerful digging organs, while the closely-set velvety fur is not readily soiled by contact with earth. The eyes, being only in the way of such an animal, INSECT-EATING MAMMALS 37 \ are reduced to a very minute size, and are not very perfectly formed. The Star-nosed Mole (Condylura cristata) (fig. 330) of North America differs from the common sort in having a much longer tail, while the snout is encircled by a number of sensitive projections, which probably are of use in detecting prey. The habits of this crea- ture resemble those of ordinary Moles. So far we have considered Insectivores which pursue their prey by running, burrowing, or swimming; but this does not exhaust the possibilities, for there are also arboreal forms, the Tree- Shrews, and leaping species, the Elephant- Shrews. Tree- Shrews (see vol. i, p. 84), which, by the by, eat fruit as well as insects, inhabit South Asia, and superficially resemble small squirrels in appearance, especially as regards the tail. It is suggested that this resemblance is a case of the well-known phenomenon termed mimicrv, where a relatively ill -defended animal is more or less protected from the attacks of its foes by being mistaken for some other creature better able to look after itself, or, it may be, possessed of noxious properties. Pre- datory animals are well aware that squirrels are exceedingly difficult to catch on account of their extreme agility, and it is quite possible that the less active Tree-Shrews lead a life of greater security on account of their squirrel-like appearance. A protective arrangement of the kind is the more necessary since the Tree- Shrews, unlike the rest of their order, feed in the day- time. The Elephant-Shrews or Jumping-Shrews of Africa (see vol. i, p. 84) are small nocturnal animals with disproportionately long Fig. 330. — Star-nosed Mole (Condyhtra cristata) 38 THE FOOD OF ANIMALS hind-limbs, and in many cases a proboscis-like snout, which has suggested one of the common names. BATS (CHEIROPTERA) The larger Bats are fruit-eaters, but the smaller ones (including all the British species) wage war against winged insects in their own element, the air. These Mammals are very similar to the Insectivora in general structure, their most noteworthy peculiarity being the possession of wings, the structure of which is described Fig. 331. — Head of Long-tongued Vampire (Chceronycteris) in another chapter, but which differ altogether from the flying organs of birds. A membrane (interfemoral membrane) stretches between the tail and legs of a Bat, into the hollow formed by which captive specimens have been observed to sweep insects before devouring them. During flight this membrane is concave towards the front, and probably serves as a means of securing prey. A good deal of the food available for animals is to be found in crevices and small spaces of various kinds, a good example being furnished by the honey secreted in tubular flowers, or in floral nectaries of tubular shape, a secretion which often serves to attract numerous small insects. In various groups of animals the tongue or other mouth-parts have acquired an elongated form, enabling them to secure food hidden away in this manner. Certain South American Bats known as Long-tongued Vampires (fig. 331) are a case in point. In this and a number of other cases the name " vampire" is probably slanderous, there being no proof of a blood-sucking habit. Observations made on captive specimens of some of the species belonging to this group INSECT-EATING MAMMALS 39 of Bats have shown that fruit is an important article of diet, but others are known to feed more or less on insects. This is the case with the Long-tongued Shrew- Bat (Glossophaga soricina], in which the long mobile tongue has a thick and roughened end. It is exceedingly probable that this organ is used in capturing the small insects harboured in the recesses of flowers, though this may not be its only use, for in an allied form it can be iSv .;, ,;^^..;; 332. — A Javelin-Bat (Phyllostonta spectrum} dexterously employed in scraping away the pulp of certain sorts of fruit. South America is also the home of two species of True or Blood-sucking Vampires. These creatures are provided with sharp -edged incisors, well -developed tusks, and cutting pre- molars. Darwin actually saw an individual belonging to the larger and commoner species (Desmodus rufus] engaged in sucking the blood from one of his horses. The teeth of these creatures are admirably suited for snipping off little bits of epidermis, so as to wound the underlying dermis, which is richly provided with blood-vessels. The stomach of these creatures is modified in accordance with the blood-sucking habit, for instead «,- THE FOOD OF ANIMALS of being a broad pouch it is a long narrow tube. An arrange- ment quite comparable to this is found in other animals which haw adopted the same kind of diet Bates and Wallace both accredit the Javelin Bats of South America with the blood-sucking habit. One species of these (Ptyffitfom* & the Pouched Mammals, or Marsupials, of which the most familiar example is the kangaroo, and which, with the exception of the American Opossums and one other form (Ccenolestes\ are now limited to Australia and some of the adjacent islands. The Marsupials present an interesting example of a group of animals which, having been long shut up in a large area presenting a great variety of physical conditions, have, in the absence of more highly organized competitors, become modified along various lines, to suit these various conditions. We thus find in Tasmania a. Native Wolf (Thylacinus), which, in its structure and habits,, resembles a member of the much higher group of Carnivora. (see fig. 312), while the Banded Ant -Eater (Myrmecobius) is adapted for catching insects much in the same way as the Great LOWER MAMMALS OF INSECTIVOROUS HABIT 43 Ant- Eater, and the little springing Bandicoots (Perameles and Cheer opus) may be compared to the Elephant- Shrews. The most Fig. 334. — Marsupial Mole (Notoryctes] recently-discovered member of the group is the Marsupial Mole (Notoryctes] (fig. 334), a small creature that pursues its way Fig. 335. — Spiny Ant-Eater (Echidna] underground like the British mole, which it superficially resembles. Yet anatomy shows that these three forms are more closely related to one another and to the herbivorous kangaroos than they are to the members of any other mammalian orders. 44 THE FOOD OF ANIMALS EGG-LAYING MAMMALS (MONOTREMES) Australia (with New Guinea and Tasmania) is also the home 01 the very lowest existing Mammals, the egg-laying Monotremes, of which there are three kinds, the Duck-Mole or Duck-billed Platypus (Ornithorhynchus)) limited to the Australian continent, and two Spiny Ant- Eaters, of which the commoner, Echidna (fig. 335), ranges from New Guinea to Tasmania. Echidna, with its narrow, toothless snout, mobile tongue^ well-developed salivary glands, and powerful digging claws, presents an insectivorous type of structure with which we are now familiar. Comparison of the various insect-eating Mammals shows that similar habits are associated with similar peculiarities of structure, and this furnishes a good instance of the same kind of classifica- tory pitfall as the one which led the old zoologists, and still leads the unskilled observer, to consider the whale as a fish. Natural- ists are now beginning to doubt the propriety of grouping the old-world Edentates with those of the new, and it has been pro- posed to create a new mammalian order — the Effodientia (i.e. Diggers) — for the reception of pangolins and aard-varks. CHAPTER IV THE FOOD OF ANIMALS— CARNIVOROUS BIRDS Birds present many interesting arrangements connected with the capture of different sorts of living prey, pursued on or in the ground, in the water, or in the air. A familiar negative character of these animals is the absence of teeth, a character which, as we have seen, is shared by some Mammals. Birds, however, were not always toothless, the most ancient fossil forms known being comparatively well off in this respect. As a good example we may take Hesperornis (% 336)> from the chalk rocks of North America, which lived at a time when the dominant back-boned animals were Reptiles. It was a large bird, measuring nearly 6 feet from the tip of the bill to the ends of the toes, and its wings were in an undevel- oped condition. This, however, was fully made up for by the powerful legs and feet, which made it an ex- pert diver and swimmer, while the long bill, probably sheathed with horn at its tip, was armed with numerous simple pointed teeth, placed in grooves, and with their points directed backwards. Hesperornis undoubtedly lived on fish, and its long toothed jaws would be well suited for dealing with prey of that kind. Fig. 336. — Head of an extinct Toothed Bird (H esperoi nis regalis] THE FOOD OF ANIMALS BIRDS OF PREY Among living birds some of the most notable groups are those which include Birds of Prey, such as eagles, falcons, hawks, and owls, and the structural features enabling them to catch small Mammals, other birds, reptiles, or fish are sufficiently obvious. Fig. 337. — A Falcon preying upon Lemmings Take, for example, any sort of Falcon (fig. 337). Here we find great powers of rapid flight, a strong hooked beak, and well- separated toes provided with large and sharp talons, which have been compared to grappling-irons; add also very perfectly -con- structed eyes and remarkably keen sight. Three toes are directed forwards and one backwards. In Owls the large eyes are suited for making the most of a feeble light. A very interesting bird of prey possessed of long legs and webbed feet, quite unlike those of the preceding, is the Secretary Bird (Serpentarius) found in South and East Africa (fig. 338). It feeds upon many kinds of reptiles, especially snakes, on which CARNIVOROUS BIRDS 47 account it is protected by the local governments. The following .account, taken from Verreaux, describes in a spirited manner the bird's tactics when attacking a snake: — " As nature exhibits fore- sight in all that she does, she has given to each animal its means of preservation. Thus the Secretary Bird has been modelled on - 338-— A Secretary-Bird (Serpentarius secretarius] attacking a Snake a plan appropriate to its mode of life, and it is therefore for this purpose that, owing to the length of its legs and tarsi, its piercing eye is able to discover at a long distance the prey which, in anti- cipation of its appearance, is stretched on the sand or among the thick grass. The elegant and majestic form of the bird becomes now even more graceful ; it now brings into action all its cunning in order to surprise the snake which it is going to attack ; there- fore it approaches with the greatest caution. The elevation of 48 THE FOOD OF ANIMALS the feathers of the neck and back of the head shows when the moment for attack has arrived. It throws itself with such force on the reptile that very often the latter does not survive the first blow." The author then goes on to describe the skilful way in which the bird avoids being bitten by the snake if the first attack is unsuccessful, using its wings as a kind of shield and its powerful feet as the chief weapons of offence. Some raptorial birds feed chiefly on fish, as in the case of certain owls which hunt their prey in rivers, ponds, and canals, while the widely-distributed Osprey or Fishing- Eagle (Pandion) swoops down on sea-fish which come sufficiently near the surface, holding them by its powerful talons aided by the roughened under- surfaces of its feet. FISH-EATING BIRDS Raptorial birds, whatever may be their prey, rely upon their mobile and powerfully - armed feet for its capture, but in other cases the beak is the seizing organ, its shape varying according to the kind of food, which also determines the nature of the hunting tactics. A number of very interesting cases are pre- sented by fish-eating birds. In these the beak is strong, pointed,, and commonly with its edge more or less saw -like, so as to securely hold the slippery prey (compare Hesperornis, p. 45), or, for the same reason, it may be hooked at the tip. Marked powers of locomotion are the rule, and the vision is keen. Cormorants, of which there are two native species, the large Black Cormorant (Phalacrocorax carbo) and the smaller Green Cormorant or Shag (P. graculus), are good examples of fishing birds. Perched on some convenient spot close to the water, they pounce suddenly down upon their victims; but this is by no means their only or even chief resource, for, being extremely expert swimmers and divers, they pursue fish on more than equal terms in the water, a favourite habit being to swim swiftly with their heads sub- merged. A small Green Cormorant (P. Capensis), closely allied to the last-named bird, is common on the coast of South Africa, and Millais (in A Breath from the Veldt) gives the following interest- ing account of its feeding habits: — " Should the traveller be so disposed, an interesting sight may be witnessed any day by CARNIVOROUS BIRDS 49 watching these little cormorants fishing. Their more ordinary method is that of singly diving in the shallows, after the manner of all their species. But instinct and an excessive abundance of their natural food has taught these birds that by uniting their forces a full stomach may be obtained with far less trouble than the methods they usually employ. The plan resorted to is as follows; and with the exception of one species of North African pelican, it is one that is not followed by any other sea-bird that I know of: — The cormorants to the number of ten or twenty form line, each bird being within a couple of feet from its neighbour, and swim along the shore at right angles to the beach, the bird nearest the land being only just able to float. In this manner they advance, constantly inspecting the water beneath by im- mersing their heads and necks until a shoal of small fish is found. Then the whole line wheels, as it were, at once shore- wards, most of the birds diving together in shallows, thus fright- ening the fish, which escape before them in such quantities that a large number are forced right out of the sea on to the beach itself. These tactics are generally rewarded by a plentiful repast, each bird resting on its breast amid the stones, and gobbling up the fish as they spring on all sides, attempt- ing to regain their natural element." The Darters, or Snake- Birds (Plotus\ of Africa, South Asia, South America, and Australia, may be de- scribed as fresh-water cormorants. They are distinguished by exceedingly sharp, slender beaks, and a narrow, swan -like neck (fig. 339). These structural features are directly related to the habits. One of these birds has been observed swimming under water in pursuit of a fish, which was ultimately bayoneted by a thrust from the beak, in making which the neck was suddenly straightened. The bird Fig. 339.— A Darter (P lotus) VOL. II. 36 5° THE FOOD OF ANIMALS then rose to the surface with its prey, which was jerked off and caught in the mouth. The Gannet (Sida Bassand), a British form, follows quite a different plan of campaign from the closely-allied cormorants. It flies about till a fish is seen, and then, rising to a certain height above it, drops suddenly down, and usually secures it. Fig. 340. — A Pelican (Pelecanus] Pelicans (fig. 340), which are allied to cormorants and gannets, abound in the warmer parts of the globe, and hunt fish in the shallower parts of rivers and estuaries, swimming with their heads under water. Like the Cape Cormorant, these birds have learnt the value of co-operation, for they commonly hunt together in long lines, a proceeding disastrous to their prey. Everyone knows that the Pelican possesses a convenient pouch hanging down from the lower part of the beak, and serving as a fish- basket. CARNIVOROUS BIRDS Gulls and Terns (fig. 341) haunt the coasts of most parts of the world, and are good swimmers and flyers, though otherwise they present no features of striking character. It is a matter of common observa- tion that some gulls are by no means limited to a fish diet, for they may often be seen some distance inland searching for worms and other small creatures. And while some of the terns are coast birds, others haunt rivers, feeding not only upon fish, but also on insects, leeches, and the like. Though closely related to the gulls, Skuas (fig. 342) in some respects remind one I of the birds of prey, for their | powerful beaks are hooked, Fig. 34I._Gulls and Terns and, contrary to the general rule, the webbed feet are provided with strong talons. These features, however, must not be taken to mean affinity with rap- torial birds, being sim- ply an adaptation to somewhat similar ha- bits. The prey con- sists of fish, small ma- rine birds, &c., which are held firmly by the strong claws. Their piratical habits are well known, for they mostly take advantage of the industry of gulls and terns. If, for instance, a skua observes that a gull has caught a fish, the result will probably be a spirited chase, resulting in the abandonment of the just-swallowed prey by the frightened victim. Upon this the pirate skua immediately pounces, often securing the Fig. 342.— Skua (Stercorarius} 52 THE FOOD OF ANIMALS ill-gotten booty before it reaches the water. These birds in- habit the colder parts of the world, but Richardson's Skua (Ster- corarius crepidatus) is pretty common in the extreme north of Scotland. Other species are also known. R. Kearton (in Wild Life at Home) gives an interesting photograph of a Great Skua or Bonxie (S. catarrhactes) attacking a watcher who has ap- proached the nest. This was taken on the island of Unst, in the Shetlands. Scissor-bills or Skimmers (Rhynchops^ constitute a small group of gull-like birds, inhabiting North America, Egypt, and India. Fig. 343.— Scissor-Bill (Rhynchops] hunting The common names have reference to the structure and action of the long compressed beak, of which the lower half projects considerably beyond the upper portion. The Scissor-bills skim along close to the surface of the water with the lower part of the beak immersed, and the upper mandible can be worked up and down so as to secure any small fishes which are so unfor- tunate as to find themselves skimmed on to the projecting part of the beak (fig. 343). Some marine birds are pelagic in habit — that is to say, are found far from land, where they play havoc among the finny tribes. The most notable of these are the Frigate- Birds, Alba- trosses, and Storm Petrels, all of which have hooked beaks and possess considerable powers of flight. The Frigate -Birds (fig. 344) are related to the pelicans, and include the Great Fri- gate-Bird (Fregatus aquila) of the Atlantic, Pacific, and Indian Oceans, and the Lesser Frigate- Bird (F. minor], from the last CARNIVOROUS BIRDS 53 two of these. H. O. Forbes (in A Naturalist's Wanaerings in the Eastern Archipelago) describes the piratical habits of the smaller species, which pursues tactics much like those already mentioned when dealing with the skuas. Speaking of the birds of the Keeling Islands, he says: " Graceful Noddies (Anous stolidus] and Gannets (Sula piscatrix) were in thousands, and I had the satisfaction of watching . . . how their industrious Fig. 344. — Frigate-Bird (Fregatus) habits are taken advantage of by the swift-winged frigate-birds. Hiding in the lee of the cocoa-nut trees, [they] would sally out on the successful fishers returning in the evening, and perpetrate a vigorous assault upon them till they disgorged for their behoof at least a share of their supper, which they caught in mid-air as it fell. . . . Refractory gannets were often seized by the tail by the frigate-birds, and treated to a shake that rarely failed of suc- cessful results." Albatrosses (see vol. i, p. 182) and Stormy Petrels are re- spectively the largest and smallest of the web-footed birds. They are representatives of two allied families belonging to the Tube- nosed Birds (Tubinares). The two groups of Diving Birds (Auks, Guillemots, Puffins, Divers, and Grebes) (fig. 345), and Penguins include those birds which are most expert at pursuing fish in the water, and the latter group represents the extreme term in the series of structural modifications for this purpose (see vol. i, p. 187). But this perfect adaptation to an aquatic life is only gained by the complete loss of powers of flight, and great limitation as regards progression on land, for the wings of Penguins are only useful as paddles, and 54 THE FOOD OF ANIMALS their legs are set on too far back to be efficient except as pro- pulsive organs in the water. The case is quite parallel with that of Seals among the Mammalia. A,piong the numerous enemies of fresh-water fish one of the most attractive is the Kingfisher (Halcyon), not infrequent in the southern parts of Britain, and distinguished by its extremely brilliant plumage. The Kingfisher plays a pre-eminently waiting game, remaining motionless on some convenient bough till a Fig. 345. — i, Red-breasted Merganser (Mergus serrator). 2, Bla tbus arcticns suitable quarry makes its appearance in the water below, when with a sudden and exceedingly rapid dart it more often than not has an opportunity of making use of its long and powerful bill. One of the most telling photographs in a recent book on birds by Kearton ( With Nat^lre and a Camera] shows the Kingfisher perched expectant on its bough, and this attitude is rendered comparatively easy to maintain by the peculiar structure of the foot, in which the toes are joined together in a remarkable manner so as to afford an unusually firm support. We have seen that Cormorants sometimes, and Kingfishers always, watch for prey from an elevated position. Many birds, however, possess long legs, which enable them to dispense with such a procedure, and also allow them actually to stand in the water on the look-out for prey. Many wading forms are included in this category, such, for example, as the Herons (see vol. i, CARNIVOROUS BIRDS 55 p. 178), of which the Common Grey Heron (Ardea cinerea] is a good example. The spreading partly -webbed toes afford a firm support to the body even on swampy ground, and the long sharp beak can be brought rapidly into action by the straightening of the long highly-mobile neck. As patient as a kingfisher, the Heron is equally ready for prompt action at the critical moment. The closely-related Stork Family includes birds of much the same build, but with somewhat different habits. The White Stork (Ciconia alba] hunts frogs and other small animals in swampy ground, walking around in a dignified manner and not waiting like a heron for prey to pass by. Numbers of the American Wood- Stork ( Tantalus loculator) co-operate to perform a sort of feeding drill, in which numbers of them tramp about in shallow water, where the bottom is muddy, till it is thoroughly stirred up, the numerous small fish, reptiles, &c., disclosed by the process being promptly bagged. CHAPTER V THE FOOD OF ANIMALS — BIRDS WHICH FEED ON INSECTS AND OTHER SMALL CREATURES— SCAVENGERS Insectivorous birds of various sorts are abundant, among which the wide-mouthed Swallows and Swifts are remarkable for their powers of flight, to which their long wings and forked tails are adaptations. The Night-Jar or Goat-Sucker (Capri- Fig. 346. — Night- Jar (Caprimulgus Europ&zts) mulgus Europceus (fig. 346) is a soft-plumaged bird, which flies something like an owl, and takes up at dusk and during the night the work which Swallows and Swifts carry on by day. Its widely-gaping mouth is fringed with stiff bristle-like feathers which are no doubt of use in the capture of prey. The following 56 BIRDS WHICH FEED ON INSECTS 57 extracts from Dixon (Among the Birds in Northern Shires] will give some idea of the appearance and habits of this interesting form: — "Like most birds possessing some peculiarity in note or appearance easily remarked by the multitude, the present species has many aliases, some of which at any rate are as undeserved ,as they are disastrous. Thus, that of 'Night- Hawk' brings the bird into evil repute with gamekeepers, and it is shot down in many localities under the firm belief that it preys upon young pheasants and partridges. That of * Goat- Sucker ' is even more widely prevailing, not only in our own country, but it has an equivalent in almost every European language, in some cases dating from a very remote antiquity. Needless to say that this appellation has proved even more fatal, and has caused the poor bird needless persecution in many other countries than ours, owing to the absurd superstition it describes and fosters of the Night- Jar's utterly fictitious habit of sucking the teats of cows .and goats. Lastly, it has been the long-suffering possessor of the names of ' Fern-Owl ' or ' Churn-Owl ', one relating to its haunts, the other to its singular note, and both suggestive of birds that have been sorely persecuted by man, in most cases for purely imaginary offences. Anything flying under the name of ' Owl ', whether with ' fern ', or * wood ', or ' barn ', or ' horned ' attached, is considered harmful, and fair food for powder and shot, so that the poor Night- Jar has suffered with the rest. To his habits and appearance most, if not all, his misfortunes are due. He flies about at dusk and during the nighttime, and has a way of flitting round the cattle in the meadows close to the heath in quest of moths and cockchafers; his plumage is soft and pencilled and owl-like, whilst his enormous mouth, to the ignorant countryman, seems capable of swallowing anything. And yet there is no more harmless bird in the British Islands than the Night- Jar. It preys upon no single creature that man might covet (if perhaps we except the entomologist, who does not like to see rare moths and beetles disappear like magic in the evening gloom), but, on the other hand, rids the fields and groves of countless numbers of injurious insect pests. . . . The bird, like the bat and the owl, sleeps during the daytime, either crouched flat upon the ground or seated lengthwise on some broad flat branch of a tree where dense foliage gives the shade and gloom it seeks, and where its beautifully-mottled and vermiculated THE FOOD OF ANIMALS plumage harmonizes most closely with surrounding tints." The Whip- Poor- Will of North America (Caprimulgus Virginianus} is a closely-allied species. Quite another sort of arrangement is presented by Wood- peckers (fig. 347), in which the foot is admirably adapted for climbing, having two long toes directed forwards and two others backwards, all being provided with sharp claws that can take advantage of the smallest ir- regularities on walls, the bark of trees, and similar surfaces. The stiff tail is also of assist- ance in climbing. The power- ful pointed and rather long beak is suited for introduction into crevices, and the mobile tongue, covered at its tip with „ backwardly - directed spines and rendered sticky by the secretion of large glands, is an excellent insect -catching organ. The arrangements found in some insectivorous Mammals are here once more recalled. It should further be added that the Fig. 347. —Greater Spotted Woodpecker (Dendrocopus major} bone ", by which the tongue is supported and to which the muscles moving it are attached, is unusually well developed, and possesses slender prolongations which curl round over the top of the head underneath the skin. The Common Cuckoo (Cuculus canorus\ which is related to the Woodpeckers, may be mentioned in passing as an insectivorous bird of great voracity, and is especially interesting as having discovered a hunting-field in which little if any competition is encountered. That is to say, it feeds largely upon hairy cater- pillars, which other birds find extremely distasteful and never touch if they can help it. Many of the sharp-beaked Perching Birds feed largely upon insects in their various stages, as well as upon other small creatures, but space forbids mention of more than a few examples* BIRDS WHICH FEED ON INSECTS 59 Among the most interesting are the Creepers, of which the Common Creeper (Certhia familiar is) (fig. 348) is abundant in Fig. 348. — Common Creeper (Certhia familiaris] Britain, though it often escapes observation on account of its dull coloration harmonizing with the tree-trunks and walls upon which it hunts insects, spiders, and other small animals. The <5o THE FOOD OF ANIMALS toes of this bird are provided with long curved claws well suited for clinging to rough surfaces, and climbing is helped by the stiff- pointed tail -quills. The long slender curved beak is sharply pointed and well adapted for probing in crannies and crevices. Fig. 349.— Blue Roller (Coracias garrulus] Although a long probing beak is common among insect-eating birds, this organ is short and conical in many species living on the same sort of food. This is the case with the attractive little Tits, which do a vast amount of execution among the branches of trees, though of course they can only reach insects, &c., which are on or near the surface, leaving those which lie deeper to be tackled by woodpeckers and creepers. The Blue- Roller (Coracias garrulus] (fig. 349), widely distri- BIRDS WHICH FEED ON INSECTS 61 buted through Europe, Asia, and North Africa, is found in districts where tall trees are mixed with underwood, and its powerful slightly-hooked beak suggests that its diet includes animals higher in the scale than insects. Such a conclusion is borne out by the facts, for it hunts upon the ground for lizards and frogs, as well as worms and insects, besides which it catches these last on the wing. The common names of some families of perching birds have reference to their insectivorous habits, as, e.g., in the case of the Fig. 350. — Crowned Tyrant (Muscivora regia) Old World Flycatchers (Muscicapidcz), represented in this country by three species, of which the commonest is the Spotted Fly- catcher (Muscicapa grisola). These birds catch insects on the wing, frequently settling on the branches of trees, from which they dart out at their prey. The American or Tyrant Flycatchers (Tyrannidtz) are dis- tinguished by similar habits to those of the last-named family. The Crowned Tyrants (Muscivora) of Mexico and South America (fig. 350) are possessed of beaks flattened from above downwards. 62 THE FOOD OF ANIMALS Some of the perching birds make a living by feeding on the insects, ticks and the like, which infest many of the larger Mammals. Such are the Ox- Peckers of the African continent, a well-known Natal species being the African Ox- Pecker (Buphaga Africand] (fig. 351). These birds are closely related to the starlings, and their feet are provided with strong curved claws, Fig. 351. — African Ox-Pecker (Buphaga Africana) by means of which, and with the help of their tails, they are able to climb about on the bodies of oxen, buffaloes, and other large animals. Their strong straight beaks deal most effectively with the creatures preyed upon, and the lower mandible is used as- a lever for extracting bot-fly larvae from the skin. J. G. Millais (in A Breath from the Veldt] gives a vivid account of the habits of this bird, from which the following is quoted: — "It is most interesting to notice the way in which a party of these birds will move about on the body of a horse or ox, searching every part of his skin as they run or hop over it in the most lively fashion. . . . It is quite immaterial to them how or in what direction they move. They are continually on the hop, and seem almost capable of hanging on by the proverbial eyelids. . . . Your oxen are no sooner outspanned than a party of these interesting- birds spy them out, and come and sit on the neighbouring trees till the beasts have been watered and have settled down to steady grazing. Then they rise in the air, and after flying in a circle once or twice over some likely-looking ox, they descend and settle all in a row along its backbone, where they sit stolidly for a BIRDS WHICH FEED ON INSECTS moment or two, to see if there is any fear of disturbance during their coming meal. The whole party then set to work and scour the entire body of the animal, a proceeding which the latter seems thoroughly to appreciate, for it is no uncommon sight to see an ox lying stretched out on the ground, exposing every part of his body to their ministrations. When they have got all they can out •of one beast they pass on to another, and repeat the process till their appetite is satisfied." While the Ox- Pecker obtains a large part of its food from the bodies of domesticated animals, another well - known and widely-distributed bird, the White-eared Honey- Guide (Indicator Sparmanni) (fig. 352), a near relative of the woodpeckers, makes use of man himself, but in a different way. Knowing that human beings have a weak- ness for honey the in- genious bird acts as .a guide to bees' nests, taking the grubs and young bees as his share of the spoil. We cannot do better than make another quotation from Mil- lais: — " The marvel- lous reasoning-power of the latter (i.e. the Honey-Guide) seems to demand' some better word than instinct. . . . Mentally marking every nest of bees in a certain locality, he hangs around till he meets with a friendly biped, to whom he makes known his presence and his desire by a pleasant chuckling note. This he keeps up incessantly as long as the man is in view. Then, after a short undulating flight of about 100 yards, he generally alights on a dead bough, so as to make himself as con- spicuous as possible, and loudly continues his chuckling. If not attended to, he returns again and again with increasing audacity, as I have previously described; but if followed, he waits till the man Fig. 352. — White-eared Honey-Guide (Indicator Sfiarmanni) 64 THE FOOD OF ANIMALS comes within 50 yards, and then continues his flights, which vary from 100 to 200 yards, till the nearest nest is discovered. There is pretty sure to be a dead bough about, or the bees would not be there; and on this he settles with his eyes towards the bees' nest. . . . The nest is generally plas- tered up with mud and not very difficult to extract ; and while you are engaged in this operation the Honey - Guide sits quietly on the tree, trust- ing to your honour to give him a share of the plunder, which I need hardly say is always done by the natives." A very curi- ous specializa- tion of the beak in reference to insect food is exhibited by the Huia (Heteralocha Gouldi] (fig. 353) of New Zealand, a member of the crow family. This bird feeds upon large beetle- grubs inhabiting decayed wood, and while the beak of the male is strong and pointed, that of the female is long, curved, and flexible. The arrangement is a clear case of division of labour, for the male is able to chip away the decayed wood so as to expose many of the grubs, while the female can insert her slender beak into holes which her partner is unable to reach. Between the two of them it fares hard with the beetle-grubs. Shrikes, or Butcher- Birds, as regards beak and feet, closely Fig. 353. — Huias (Heteralocha Gould f) BIRDS WHICH FEED ON INSECTS 65 resemble birds of prey. They feed on insects and small verte- brates, and impale such prey as are not immediately required upon thorns, often forming in this way a very respectable "larder'* (fig- 354)- ^ A considerable number of well-known birds feed upon worms, snails, and other small animals which are found in the mud of Fig- 354- — Great Butcher-Bird (Lanius excubitor) ponds and streams, or in damp marshy places. Everyone has seen a Duck in the water, with its tail turned up, engaged in this sort of work, and in this animal the broad bill (fig. 355) acts as a strainer, and is exquisitely sensi- tive, enabling the creature to effectively sift the wheat from the chaff, if such a meta- phor be permissible. The long neck of the Swan enables it to investigate somewhat deeper water with the same practical aim. Ducks and Swans, however, are not purely carnivorous. A number of birds are fond of haunting the banks of streams and ponds with a view of catching insects and other small animals. Among the most attractive and familiar of these are the Wagtails (fig. 356), of which there are five British species, the most familiar being the Pied or Water Wagtail (Mota- cilla lugubris\ The slender pointed beak is obviously suited to an insect diet. W. Warde Fowler (in Summer Studies of Birds and Books] speaks thus of the little group of birds now under considera- 355-— Head of Duck (Anas boschas) VOL. II. 37 66 THE FOOD OF ANIMALS tion: — ''It is impossible ever to weary of Wagtails. We are never altogether without them, yet whenever they present themselves to us we are constrained to give them our attention. . . . They all Fig. 356.— Yellow Wagtail (Motacilla flavd) walk, or rather run, instead of hopping, their delicate little legs being often in such swift motion as hardly to be seen as they go; and all feed chiefly on insects — largely, I think, on minute beetles Fig- 357-— Black-tailed Godwit (Limosa Belgica] — and love our British streams and meadows for the never-failing abundance of food they find there." The sea-shore is a favourite resort of many birds besides the BIRDS WHICH FEED ON INSECTS 67 fish -eating forms, some species making it their usual hunting- ground, while others make occasional visits. Among the former may be mentioned two interesting birds of the Plover Family — the Turnstone and the Oyster-Catcher. Everyone who has hunted for little beasts along the shore, and most of us as children have Fig. 358. — Curlew (Ntimenins arquatus) done so, knows that sand-hoppers, small crabs, and a host of other diminutive creatures harbour under stones. The Common Turnstone (Strepsilas interpret) is well aware of the fact, and uses his strong beak for turning over stones, a method of pot- hunting which brings its own reward. The black-and-white Oyster-Catcher (Hcematopus ostralegus] possesses in his powerful laterally -compressed beak a means of opening various bivalve 68 THE FOOD OF ANIMALS molluscs, of detaching the tenacious limpet caught unawares, and of securing sundry creatures which burrow in the sand and thoughtlessly come too near the surface. Godwits (fig. 357) and Curlews (fig. 358) are plover-like birds with long legs which enable them to wade to some extent when searching for food. The long slender beak (curved in the Cur- lews) is well suited for probing in mud, moist earth, or sand, with the object of securing such small animals as live therein. During the summer these birds frequent moors and marshy uplands, and vary their animal diet with berries and the like, but in winter they haunt the sea-shore, and are then more strictly of carnivorous habit. The last point suggests the habits of another member of the Plover Family, e.g. the Long- beaked Woodcock (Scolopax rusti- Fig. 359.— Woodcock (Scolopax rusticola] cola) (fig. 359), which searches for worms along the banks of streams and in marshy ground. The sensitive beak bores deep into the mud, and is kept motionless until, perchance, some con- tiguous worm inadvertently wriggles, and next moment is as often as not captured by a sudden thrust on the part of the aggressor. A similar procedure is adopted by the smallest living flightless bird, the Kiwi (Apteryx) (see vol. i, p. 190) of New Zealand, and in this case the nostrils are placed close to the tip of the long beak, a very unusual position. As might be expected BIRDS WHICH FEED ON INSECTS 69 from this arrangement the Kiwis largely rely on the sense of smell when hunting for worms, at which time they make a sniffing sound. Unlike the woodcocks they appear to detect their prey before driving in the beak, as this procedure is commonly success- ful straight away. There are among Birds, as among Mammals, forms which are specially adapted to feed on carrion. The best known of such scavenging birds are Vultures and Adjutants. The former are closely related to the Hawks, but present a peculiar appear- ance owing to the bareness of their heads and necks, a feature which has obvious relation to the nature of the food. Adjutants, which are to be looked upon as large and specialized Storks, present the same peculiarity, which is no doubt an adaptation to the same end. CHAPTER VI THE FOOD OF ANIMALS— CARNIVOROUS AND INSECTI- VOROUS REPTILES CROCODILES Reptiles exhibit many forms of adaptation to an animal diet We may fitly begin with the CROCODILES and their allies, which are at the same time the most highly organized and the most formidable members of the class (see vol. i, p. 21 ). The well-known Nile Crocodile (Crocodilus Niloticus) will serve as an average illustration. The seizing organ is here constituted by the powerful jaws, with their numerous strong, pointed, and interlocking teeth, which, once having got a firm grip, rarely leave go. Even a large Mammal, when caught, struggles in vain, but is steadily drawn under water and drowned, after which it is devoured by a series of tearing snaps. The Crocodile itself might easily get choked during this drowning process were there not some special provision to prevent it. This preventive arrangement consists in the extreme backward posi- tion of the internal nostrils, and the upward projection of the top of the windpipe into the hinder part of the nasal passages. Thus the mouth can be kept more or less open under water without any risk of suffocation. We are reminded here of a similar contrivance among the Cetacea, the existence of which is due to a similar reason. Although Crocodiles are capable of fairly rapid progression on land, they are specially adapted to swift movement in the water, the laterally-flattened tail acting as the organ of propulsion. This powerful structure can also be used as a flail, by the sudden use of which unwary animals standing close to the water's edge, as for the purpose of drinking, are swept within the range of the jaws. Much, if not most of the success of the Crocodile as a hunter, is due to his craftiness. Floating like a log in the water he is able to approach his prey 70 CARNIVOROUS AND INSECTIVOROUS REPTILES 71 without arousing suspicion till within striking distance. The following quotation from Sir Samuel Baker (in Wild Beasts and their Ways) furnishes a good example: — " I have watched upon many occasions the stealthy advance of a crocodile to capture small birds, when in flights of many thousands they have settled upon the yielding branches of dwarf willows overhanging the Atbara river. The elastic boughs bent down beneath the weight of the innumerable flock, and the crocodile's head appeared above the surface at a distance, sank below, and quickly reappeared (the eyes and crown alone above the water) within 10 yards of the unsuspecting birds, all of which were busily engaged in twittering excitement, quarrelling for places, and occasionally dipping their beaks in the water when the bending twigs per- mitted them to drink. In a few moments after the disappearance of the wary eyes a tremendous splash was accompanied with a pair of open jaws, which swept the occupants of the lower branches into the greedy throat. This artful attack was frequently repeated, and generally with success." As regards the internal arrangements of the Crocodile it may be noted that the gullet is very dilatable, allowing prey of con- siderable size to be swallowed, and part of the stomach is a sort of gizzard, within which stones and gravel are always to be found. Here, as in the case of birds, is an arrangement which compen- sates for the absence of chewing organs. As might be expected, fish is an important item in the diet of members of the group under consideration, but the slender- snouted crocodiles known as Garials appear to be specially adapted to this kind of food. The Gangetic Garial (Garialis Gangetica), for example, which inhabits some of the Indian rivers, possesses a very long beak-like snout armed with very numerous teeth, and well suited for dealing with this kind of prey. A com- parison naturally suggests itself with some of the fishing-birds, and still more with the curious Cetacean known as the Gangetic Dolphin (see p. 28). TORTOISES AND TURTLES Some of the members of the TORTOISE and TURTLE ORDER are of carnivorous habit, but there are no very special adapta- tions to an animal diet. It is among the fresh -water forms that THE FOOD OF ANIMALS those most addicted to animal food are to be found, and decidedly the most aggressive of these are the American Snapper-Tortoises, of which an example is the Alligator-Terrapin (Chelydra serpentina), which ranges from Canada to Ecuador on the eastern side of the mountain axis of the New World. As the common name suggests, there is a powerful flattened tail, which serves as an efficient swim- Fig. 360.— Hawk-bill Turtle (Chelone imbricata) ming organ, enabling the animal to overtake the frogs and fish upon which it chiefly feeds. Its powerful jaws are covered with a strong horny sheath, and they are brought together with a sudden and effective snap at the psychological moment. The Hawk-bill Turtle (Chelone imbricatd), from which the " tortoise-shell" of com- merce is obtained, is also purely carnivorous in habit, and its hooked beak is correlated with the nature of its food (fig. 360). In most Chelonians the rigidity of the trunk is made up for by the extreme mobility of the neck, and in some members of the order this would appear to be of importance in the capture of prey. The Snake-necked Tortoises (Hydromed^tsa] of South America, for example, possess exceedingly long necks, which can either be folded back within the shell or thrust out with great swiftness. CARNIVOROUS AND INSECTIVOROUS REPTILES 73 LIZARDS The large and widely-distributed order of LIZARDS is in the main an assemblage of carnivorous species, most of which are suited to a life on land. All sorts of animals serve as food, from small backboned animals down to insects, snails, and worms. Our native species are typical representatives of an Old World family rich in species, of which the chief food is insects. Extreme agility and the possession of numerous small, pointed teeth are obvious attributes, both of which appear to be related to the nature of the food. The Monitors constitute a group of large Lizards ranging from Africa through the south of Asia into the Australian region, and feeding upon various backboned animals, such as frogs, reptiles, birds, and small mammals. As might be expected from the nature of the food, the teeth are large and pointed. The different species live in very different surroundings, and exhibit specializations of corresponding kind. The Desert Monitor { Varanus griseus) inhabits the deserts of North-west Africa and South-west Asia, and is rendered inconspicuous in its natural surroundings by its dull coloration. The powerful cylindrical tail is used as a weapon. The Papuan Monitor ( V. prasinus) is believed to live among trees, and its tail is shaped like that of the last-named species. Most of these Lizards, however, have tails which are strongly flattened laterally, a feature usually associated with the power of swimming. An example is the Nile Monitor (V. Niloticus] (see vol. i, p. 224), which frequents most of the African streams, and preys largely upon the eggs of crocodiles. And as a last example we may take the Water Monitor (V. sal- vator], which is the largest of the series, attaining a length of pretty nearly 7 feet. Its range extends through South Asia to Australia, and it is mostly found in marshy ground in the neigh- bourhood of water, both salt and fresh. Not only can the animal swim, but also climb among trees, devouring smaller lizards and also birds, as well as the eggs of the latter. It has a curious method of egg-eating, for an egg is first seized in the jaws, the head is turned up, and the egg-shell broken with the teeth in such a way that the contents can be readily swallowed. Among the most interesting climbing lizards are the small insect-eating forms known as Geckoes and Chameleons. Geckoes 74 THE FOOD OF ANIMALS (see vol. i, p. 221) are exceedingly active creatures, in which the toes are provided with climbing pads on the under -surface, the structure of which will be described elsewhere. Almost univer- sally distributed throughout the hotter parts of both New and Old Worlds, including Australia, the Geckoes have attracted a good deal of attention from the fact that they are often found in houses, hunting down insects on the walls and even on the ceilings, along which they can climb in an inverted position. Even better known than the Geckoes, on account of their quaint form and power of changing their colour to harmonize Fig. 361. — Chameleon seizing its Prey with local surroundings, are the Chameleons (fig. 361), which are distributed throughout Africa, and are also found in western and southern Asia. All the Lizards, so far considered, are distinguished by their extreme activity, but the Chameleon is a sluggish creature as regards locomotion, and is usually found holding firmly on to a branch by means of a prehensile tail and very curious feet, in which the digits are bound together in two groups, so as to give considerable grasping power. No better description has ever been written of the way in which a chameleon catches its prey than that by Professor Lloyd Morgan (in Animal Sketches], from which the CARNIVOROUS AND INSECTIVOROUS REPTILES 75 following is quoted: — ". . . Our chameleon is a beast of prey. Insects are its food. See, a fly has settled on that bough, within six inches of our largest lion. But what chance has the slow and sedate chameleon, slowest and sleepiest of lizard-folk, what chance has he of catching an active and wary fly? His cone-shaped swivel eyes are looking about aimlessly, each seeming bent on some business of its own. Now one glances lazily up, while the other peers furtively down. Now one is staring attentively back- wards at its owner's tail, while the other is ranging round the neighbourhood of that wide-awake little fly, who is rubbing her front legs together, or drawing her hind-legs over her wings, in utter carelessness of the presence of so inanimate an enemy. But make not too sure. One eye has ceased its aimless wandering, and becomes earnestly interested in that fly. The chameleon takes one solemn step forward. You are all right for the pre- sent, Mrs. Fly; but let me advise you to be careful and circum- spect. That one eye is fixed upon you with an unchanging, steady gaze, and the other seems somehow to have lost its interest in its owner's tail, and is beginning to find a new interest in your immediate neighbourhood. If once that other eye becomes fixed upon you, take my word for it, you're a doomed fly. Ah! I thought so. The other eye has come to rest, and holds you in its steady gaze. The chameleon leans forward a little, his mouth slowly opens, twitches once or twice, and quick as thought, with unerring aim, a long worm-like tongue is darted forth and returns to the mouth like a piece of stretched india-rubber. Where is poor Mrs. Fly? She seems to have disappeared. And Mr. Chameleon is leisurely munching at something which seems to give him some sort of sedate satisfaction." Here again we have the device of a long sticky tongue as an insect-trap that was noted in some ant- eating mammals and in woodpeckers. In this case the organ in question has a curious swollen end. We have seen that Lizards of various kinds hunt their prey on the ground, among trees, and also in the water; but this does not exhaust the possibilities of the group, for there are a number of burrowing species. Prominent among these are the Skinks, stumpy-looking creatures, in which the spindle-shaped body with smooth surface is well suited to the habit, to which the short powerful limbs and transparent lower eyelid, acting as a protective window, are further adaptations. Types of the group are the 76 THE FOOD OF ANIMALS Common Skink (Scincus officinalis) (fig. 362) of the Sahara and Red Sea regions, and the remarkable Stump -tailed Lizard (Trachysaurus rugosus) (see vol. i, p. 226) of Australia. Specialization of a far more profound nature to suit a burrow- ing habit is displayed by the worm-like Amphisbaenas, most of which are natives of the hotter parts of Africa and America, and which owe their name to the fact that they can move forwards or backwards with equal ease. The Handed Amphisbaena (Chirotes caniculatus\ native to California. and Mexico, is one of the least modified members of the group, for it still possesses small fore-limbs, though the hind ones are entirely absent; but in most other cases, as, for example, in the Spotted Amphisbsena (A. fuliginosa) of tropical America and the West Indies, neither pair of extremities is present. The food consists of insects and worms. There is another group of Lizards in which the body is long and cylindrical, so as to give a snake-like appearance. These Snake-like Lizards (see vol. i, p. 225) are adapted for progres- sion through thickly -growing vegetation, like the animals they resemble, and according to their size they prey upon either small vertebrates or various lower forms of life. Natives of America, and to a less extent of Europe and south Asia, some of those from the first -named continent, possess small limbs. Many species, however, are quite devoid of extremities, as illustrated by the common Blind- Worm (Angms fragilis], which frequents woods, downs, and heaths in Britain, feeding upon snails, slugs, worms, and insects. SNAKES The members of the vast order of Snakes, which reaches its maximum development in tropical regions, are specialized on somewhat the same lines as the snake-like lizards. Like these they are undoubtedly descended from reptiles possessing well- developed limbs, and in some of the large snakes, such as pythons, insignificant vestiges of the hind-limbs are still present, but are not concerned in locomotion. Snakes exhibit a great diversity of habitat. The large majo- rity pursue their prey upon the ground, others live among trees, some few burrow in the ground, while others again are adapted CARNIVOROUS AND INSECTIVOROUS REPTILES 77 78 THE FOOD OF ANIMALS for life in fresh water or even in the sea. The prey in most cases consists of living animals, often of relatively large size, and it is clear that a comparatively narrow animal, devoid of any chewing arrangement, must be modified in structure so as to enable it to deal with such prey, which after capture has to be swallowed whole. The mouth, of course, must be capable of great dilata- tion, and this is made possible by the presence of a double hinge- joint where the lower jaw is attached, and by the fact that the two halves of the lower jaw are connected in front by an elastic band instead of being firmly united together as is the rule in backboned animals. Escape of the prey when this is swallowed alive, as is usually the case, is prevented by the sharp, backwardly - curved teeth. There must also be some way of preventing the snake from choking during the slow process of swallowing, and this is found in the peculiar nature of the top of the windpipe, which is drawn out into a cone that protrudes from the corner of the mouth while the prey is passing slowly down the gullet. Not only is the mouth capable of great expansion, but also the gullet and stomach, as well as the part of the body in which they are contained, an important point to notice here being the complete absence of a breast-bone and limb-girdles, which, if present, would prove a serious hindrance to the excessive dilatation which is absolutely necessary. Although an average snake affects meals of a bulky sort, which are digested with comparative ease, long intervals elapse between them. A constant supply of water for drinking is, however, indispensable. Snakes have various ways of dealing with their prey, and it will be convenient to take harmless forms first, afterwards con- sidering the nature and mode of action of the poison-apparatus in the venomous species. A convenient point of departure is afforded by the common Grass Snake (Tropidonotus natrix) (see vol. i, p. 233) of Britain, which feeds on frogs, small mammals, birds, and even fishes, for it is an expert swimmer. These are secured by the numerous pointed teeth, and swallowed alive. The unfor- tunate frog, which has so many enemies, from man downwards, is the favourite prey of this snake, which, as so often happens with these reptiles, seems to exert a kind of hypnotic influence upon it, for, instead of trying to escape, it stands still, uttering cries of fear. Next moment it is seized and gradually swallowed, protesting meanwhile in a way which is far from pleasant to witness. POISONOUS ASIATIC SNAKES Poisonous serpents, which for the most part inhabit tropical or ^sub-tropical regions, are provided with very effective offensive and defensive weapons, in the form of poison-glands, of which the venom is conveyed along certain specialized teeth, known as the •"fangs", into the wounds made by these organs. It is a case of biting, and not stinging as often supposed. Often, but by no means always, the presence of the poison-glands causes the head ito be broadened out behind. Some such forms evade obser- vation by being coloured in such a way as to harmonize with the •colour-scheme of their surroundings. Others exhibit striking tints and patterns which make them very conspicuous. This Warning Coloration advertises their noxious properties to animals which anight otherwise destroy them. The conspicuousness may be increased by the assumption of Warning Attitudes, or the emission «of Warning Sounds. CARNIVOROUS AND INSECTIVOROUS REPTILES 79 The largest known snakes, Pythons and Boas (see vol. i, p. 231), as well as many smaller kinds, adopt a much more merciful procedure than the Grass Snake, for they kill their prey by crushing it in their coils before beginning to swallow it, the latter proceeding being greatly facilitated by the secretion of large quantities of saliva. The largest of all such species is the gigantic Anaconda (Euneces murinus}, inhabiting the tropical forest regions of South America, where it haunts the rivers and their neighbour- hood, often hanging head downwards from a tree on the look-out for prey. Many such reptiles are thoroughly arboreal in habit, as for instance the Tree -Boas of tropical regions, though their climbing powers do not preclude expertness in swimming. A certain number of snakes are adapted for pursuing such prey as can be found underground, more especially earth-worms. The most important are the Shield-tailed Snakes (Uropeltidcz) of India and Ceylon, and the widely-distributed Blind- Snakes (Typhlopidce), found for the most part in tropical regions. They are never of large size, and their smooth scales present but little resistance to passage through the earth, while, as so often happens in creatures which lead an underground life, the eyes are much reduced, and in this case are protected by special shields. The nature of the food does not demand those expansive powers which are so characteristic of average snakes, and the mouth is consequently small and incapable of being stretched to any extent. Poisonous Snakes. We now pass to the consideration of poisonous forms, which are distinguished by the grooved or tubular nature of some of the teeth attached to the margin of the upper jaw, the object of this being to conduct poison into any wound which may be inflicted. Such modified teeth may be situated either at the front or back, and though their presence may be taken to indicate a greater or less degree of poisonous properties, it by no means follows that all such forms are dan- gerous to man. The slender Whip- Snakes (Dryiophidcz) of India and the Malay region are among the forms where the poison-fangs are formed by modification of the hinder teeth. They are arboreal in habit, climbing among trees with great rapidity, and preying upon small vertebrates, such as birds and lizards. Well-known examples of venomous serpents, in which the poison-fangs are at the front end of the upper jaw, are the brilliantly-coloured Coral- Snake (Elaps] of South Africa and the hotter parts of America, 8o THE FOOD OF ANIMALS the Cobra de Capello (Naia tripudians) and Giant Cobra bungarus] of South Asia, the African Asp (N. haie), and the Death- Adders of the Australian region. Here also are included the poisonous Sea-Snakes (Hydropkida) of the Indian and Pacific Oceans. The poison arrangements, however, are by far the most specialized in the great group of Vipers (Viperidcz\ represented in this country by the Adder (Pelias berus\ and which includes such notorious forms as the Puff Adder ( Vip^ra arietans) of Africa and the Rattlesnake (Crotalus durissus) (see vol. i, p. 235) of North America. It is serpents of this kind in which the flattened head, broad at the back, presents the oft-cited resemblance to the ace of spades. The breadth is mainly due to the presence of very large poison- glands, one behind each eye (fig. 363). These are modified salivary glands, and therefore furnish an instance of the prin- Fig. 363.-skuii of Rattlesnake ciple °f " change of function" which has a, Brain-case; b, maxilla; c, poison-fang; elsewhere been noted. Each of them is a, lower jaw. covered by a layer of muscle, which by its contraction forces out poison into the fang-canals at the moment when the snake opens its mouth to " strike" its prey. It is, however, in the structure of the upper jaw that the viperine snakes are most remarkable. The external bones (maxilla) of this region are attached by a hinge -joint to the skull, so that they can be moved forwards or backwards. They are extremely short,, and instead of carrying a number of teeth, as in the front-fanged and hind-fanged species, each of them bears but a single tooth in the form of a long sharp poison-fang, traversed by a canal which is open both above and below. Through the upper opening poison is passed into it, flowing out again by the lower aperture placed near but not actually at the tip of the fang. Were the opening in the latter position it would be liable to blockage, but as it is a wound can be inflicted without danger of this. The piercing tube (cannula), attached to a hypodermic syringe, such as doctors employ for injecting various solutions (morphia, &c.) under the skin, is constructed on the same principle. As often remarked, many of the products of human ingenuity are copied from or anticipated by structures possessed by the bodies of animals. CARNIVOROUS AND INSECTIVOROUS REPTILES 81 When the mouth of a viper is closed the poison-fangs are backwardly-directed and pressed closely against the palate, but when the mouth is opened a series of slender bones running forwards from the joint of the jaw pushes the movable upper- jaw-bone forwards, causing the fangs to be " erected", i.e. rotated downwards and forwards, so that they are ready for use. Closure of the mouth reverses the action, enabling the snake to " strike " or bite its prey. As, too, the fangs are very brittle, and therefore liable to be broken off, a number of small " reserve fangs " are imbedded in the jaw at the base of the one actually in use, and these grow up one after another as required. Poisonous snakes even more than some of the harmless kinds are accredited with powers of ' ' fascination "; in other words, they appear to be able to hypnotize their prey. It has been suggested that the rapid movement of the tongue may play an important part in this process, just as in the human subject a state of trance can often be brought about by gazing at a rapidly- revolving mirror or " lark-mill". Some of the venomous serpents are so coloured and marked that they harmonize with their surroundings; a case of " aggressive general resemblance ", so called because it aids them in their pursuit of prey, which are thus apt to be caught unawares. VOL. II. 38 CHAPTER VII THE FOOD OF ANIMALS— AMPHIBIA AND FISHES OF CARNIVOROUS AND INSECTIVOROUS HABIT AMPHIBIA We find the members of the class AMPHIBIA preying upon insects, worms, snails, and the like, both on land and in fresh water. Only a few of the more striking adaptations in the group will be mentioned, and in this connection one of the most interesting species is the common Grass Frog (Rana temporaries). Like the Chameleon, this animal is capable of changing its hue according to the nature of its surroundings for the time being, the alteration in colour being, however, less rapid. The Frog also possesses a sticky tongue, which can be shot out for some distance for the purpose of catching insects, but the mechanism is somewhat different from that present in the Chameleon. The tongue here is forked, not club- ended, and when not in use is directed backwards, its attached part being fixed to the floor of the mouth far forwards. When shot out, an action which can be very rapidly effected, its tip brushes past the front part of the roof of the mouth, taking up some of a sticky fluid which exudes from some spe- cial glands belonging to that region (fig. 364). The tongue is then quickly drawn back into the mouth, carrying the catch with it. The Common Toad (Bufo vulgaris) captures prey much in the same way as the Frog (fig. 365), and it is also fond of worms, tackling even large ones with the aid of its feet. Some of the tailless Amphibians, such as the Tree- Frogs, of which a little green species (Hyla Europea) is well known on 82 Fig. 364. — Tongue of Frog extended to secure its Prey FISHES 83 the continent of Europe, are aboreal in habit, and harmonize in colour with the foliage which surround them. Tailed Amphibians differ a good deal among themselves as regards their habits. Some of them, as the Spotted Salamander (Salamandra maculosa) (see vol. i, p. 246), devour snails and such other small invertebrates as are to be found in damp places on the land, while many are aquatic, among these being the Newts and Fish- like Salamanders. Cases have already been noted of snakes and snake -like lizards 11. FiS- 365-— Toad catching its Prey which burrow in the earth, and this habit also finds illustration among the Amphibia in the case of the blind and limbless Caecilians (see vol. i, p. 255), which possess long worm-like bodies, and pursue earthworms, &c., underground. FISHES The enormous class of FISHES is pre-eminently carnivorous, and its members present many interesting structural features having reference to the nature of the food. The several orders may be considered in succession. LUNG-FISHES OR MUD-FISHES (DIPNOI) The Lung-Fishes or Mud-Fishes (Dipnoi) (see vol. i, p. 265) of Africa, South America, and Australia, are all carnivorous, and their mouths are armed with broad bony plates suited for crushing. The South American Mud- Fish (Lepidosiren) of the Amazon and Paraguay rivers has been showrn, in the latter locality at least, to feed very largely upon a large kind of fresh-water snail (Ampullaria), the shells of which are easily crushed by these strong dental plates. The habits of the African Mud- Fish (Proiopterus)^ judged by the behaviour of captive specimens, are in many respects similar, but their diet would appear to be of a more varied character. Semon (In the Australian Busk) makes the following remarks about the food of the Australian Mud- Fish (Ceratodus]\ — "Now and then our baits of meat or molluscs 84 THE FOOD OF ANIMALS attracted a Ceratodus, and this proved that the Australian lung- fish is by no means a vegetarian, as has hitherto been thought. On opening the animal, the intestinal canal will indeed almost always be found filled with green vegetable matter, partly com- posed of leaves and blossoms of gum- and tea-trees, carried into the river by the wind, partly of genuine water-plants. But noting that Ceratodus took so well to animal bait, I grew doubtful whether the above-mentioned plants are eaten for their own sake, or for the sake of the many little animals : craw-fish, worms, snails, shell-fish, and insect-larvae, which they harbour. On examining the contents of the intestines, I found that the tough fibres of the plants are not digested, but leave the body in an almost unchanged state. They are, so to say, but the vehicles of the food itself, which is of essentially animal character." ORDINARY BONY FISHES (TELEOSTEI) The ordinary Bony Fishes (Teleostei), which include the vast majority of existing piscine forms, present many examples of special adaptations to an animal diet. A very large number of species are provided with numerous small, pointed teeth, which are of no use for masticatory purposes, but constitute an efficient seizing apparatus, fatal to many sorts of prey, from other fishes downwards. Among common predaceous species which possess numerous teeth of this kind are the Fresh-water Perch (Perca fluviatilis) and its many allies, the members of the Mackerel Family, and the voracious Pike (Esox lucius). It is the rule for the teeth to be backwardly-directed, so that the prey cannot escape after having been once secured. Lures. — A further specialization in the direction just indicated is found in the ugly Angler- Fish or Fishing- Frog (Lophius piscatorius] (fig. 366), common in shallow water round our coasts. Here the huge mouth is beset with large, pointed teeth of various sizes, those in front being hinged on the jaws so that they are easily pressed down to admit of the entry of prey, for which, however, exit is quite another matter, as, after depression, the teeth spring up again by the action of elastic ligaments. This ungainly fish lurks on the bottom, with which it harmonizes in colour, the hue being capable of alteration to suit different sur- roundings (aggressive variable coloration). Its paired fins are FISHES 85 used for crawling, and also for heaping up loose material around its body. When in wait for prey it remains motionless, and there are tags of skin attached to the margins of the jaw which float out and look like bits of sea-weed. And further, it is possessed of a fishing-rod carrying a " lure ", for the long spines of the first dorsal fin are unconnected by membrane, and the first of Fig. 366. — Angler-Fish (Lophius piscatorius} them broadens out into a sort of flap, which waves about a little way above the mouth, exciting the curiosity of smaller fishes. If these are so foolhardy as to venture near, the Angler makes a sudden spring and engulfs them in his capacious mouth. A still more remarkable arrangement as regards the "lure" is to be found in a related species, the Deep-sea Angler {Melano- cetus Murrayi) (fig. 367), which inhabits depths of from 1850 to 2450 fathoms. The arrangement is described in the following quotation from Hickson (The Fauna of the Deep Sea): — "The eyes are very small indeed, the mouth huge and armed with long, uneven, rasp-like teeth. At the end of the fishing-rod tentacle hanging over the mouth there is an organ that has been 86 THE FOOD OF ANIMALS supposed to be capable of emitting a phosphorescent light. This curious modification of the red-worm-like bait of the common shallow-water angler into a will-o'-the-wisp lantern, attracting little fishes to their destruc- tion in the deadly jaws of the Melanocetus, is one of the most interesting adaptations that has been brought to light by our study of the deep-water fauna. " Crushing Teeth. — Many bony fishes feed upon mol- luscs, hard-shelled Crustacea, and other creatures which require crushing before they can be digested, and in these forms the teeth, or some of them, are converted into firm plates suitable for mastication. Such teeth are present in the Wrasses, shallow- water species which feed on crusta- ceans, molluscs, and in some cases on corals. Many of these fishes are provided with a strong, curved upper tooth at each angle of the mouth, the use of these being to hold the food in position between the crushing front and side teeth. Attention may also be called to the voracious Wolf- Fishes (Anarrhichas), gigantic members of the Blenny Family, which inhabit the northern parts of the great oceans. In these creatures not only are the margins of the jaws provided with strong blunt teeth, but there is also a longitudinal band of similar teeth on the palate. Electric Organs. — Certain fishes are provided with electric organs, with which they are believed to kill or stun their prey, and which have been produced by modification of some of the muscles (fig. 368). Those belonging to the group now under consideration are inhabitants of fresh water. They include the Electric Cat-Fishes of tropical Africa and the Electric-Eel from tropical South America. The last may be as much as 6 feet in length. Fig. 367. — Deep-sea Angler (Melanocetus Murrayi] FISHES Shore -Hunters. — Widely distributed along the tropical and temperate coasts of the world are to be found the Gobies, which constitute a family of small carnivorous species. Some of these, known as Mud -Skippers, abound in the I ndo- Pacific region and are represented on the west coast of Africa, one extremely common kind from the former area being Periophthalmus Kozlreuteri. This, like the other allied species, instead of keeping to its own proper element, makes a hunting-ground of the shore between tide-marks, especially when it is muddy or uneven, and littered with brown sea-weeds or mangrove roots. Progressing by a series of hops, effected by means of the tail and strong, paired fins, it pursues relentlessly small crabs and other invertebrates, and such insects as mosquitoes have been found in its stomach. The large protruding eyes are capable of very free movement, and an investigation of their °" either side are seen four masses e> of muscle (darkly shaded). The structure has shown that they are as useful wedge-shaped structure beiow is i i . i the ventral fin. on land as in the water. Insect- Eaters. — Insects are included in the diet of the last- named fish, and it is, of course, a common thing to see fish rise at " flies" which fall into the water, but a much more interesting case is that of the Beaked Chelmon (Chelmon rostratus], an in- habitant of Indian rivers and estuaries. It possesses a long tubular snout, from which it is said to be able to eject drops of water for a distance of several feet with considerable force, the object being to knock into the water insects which have alighted on vegetation near the edge. Use of Sense Organs. — Among the higher back-boned animals cases have been cited where the senses of touch, smell, and sight respectively are of importance in the detection or pursuit of prey. Ducks, dog-like animals, and vultures may be mentioned as typical instances. Fishes afford examples of all three cases, but it will be convenient to postpone details till organs of sense are dealt with in a later section. Fig. 368. — Cross-section through Electric Eel o o, Electric organ, above which 88 THE FOOD OF ANIMALS SHARKS AND RAYS (ELASMOBRANCHS) Typical Sharks. — The order of Elasmobranch fishes, including Sharks, Rays, and their allies, is essentially a predaceous one. In such a typical member of the group as the Blue Shark (Car- char ias glaucus] (see vol. i, p. 285) the jaws are found to be armed with numerous rows of sharp triangular teeth, forming very effi- cient offensive weapons. The large moutk is situated far back on the under side of the head, a fact which accounts for the well- known habit this and other sharks have of turning over on their backs before seizing prey. This particular species commonly attains the length of 1 5 feet, while allied species may be as much as 25 feet long. Much larger proportions are exhibited by the Rondeletian Shark (Carcharodon Rondeletii\ which has a wide distribution throughout the hotter parts of the ocean, and for which a length of 40 feet is recorded. It must not, however, be supposed that the size of the prey is proportionate to the size of the shark, or that all large species are dangerous to man. The size and character of the teeth afford a much safer guide to the habits. For example, the Basking Shark (Cetorhinus maximus], which is the biggest of its kind to be found in the North Atlantic, attaining as it does a length of 30 feet or more, is perfectly harm- less if left alone, and feeds upon comparatively small animals. In accordance with this its numerous conical teeth are of small size. "Shepherding" of Prey. — Another interesting species with rela- tively small teeth is the Thresher (Alopecias vulpes], distinguished by the extreme length of the upper lobe of its tail, which is longer than the rest of the body. The food consists of fish which swim in shoals, such as herrings, and the common name indicates the function of the long tail, which is used as a flail to beat the water, so that the frightened prey may be induced to herd closely together, with the result that their capture is easy. Saws. — Teeth are by no means the only weapons of offence possessed by the Shark tribe. In Saw- Fishes (Pristidce), for example, which are widely distributed through the hotter parts of the sea, and are known to ascend some of the Indian rivers, the snout is drawn out into a long flattened process armed on either side with a row of powerful tooth-like scales, that have nothing to do with the ordinary jaw -teeth (fig. 369). Such FISHES 89 " saws " are among the common objects seen in museums, or brought home by sailors. Powerful side -strokes can be given Fig. 369. — Saw-Fish (Pristis antiquorum] with these formidable weapons, which in extreme cases may be 6 feet long. Crushing Teeth. — Some sharks present a parallel to the arrangements already described for Wrasses and Wolf -Fishes, their teeth having broad crushing crowns adapted for breaking the hard investments of various invertebrates. An example is furnished by the Port Jackson Shark (Cestracion Philippi] Fig- 370.— Port Jackson Shark (Cestracion Philippi) (fig. 37°)> which feeds upon molluscs, and in which the mouth is placed at the front end of the head, a more convenient place than is usual among sharks. In this fish the front teeth are small and pointed, while the remainder are adapted for crushing. Rays and Skates (see vol. i, p. 289) are bottom-fishes, inca- pable of swimming with the rapidity characteristic of typical sharks. They therefore, as might be expected, feed chiefly upon inver- tebrates, in accordance with which their numerous rows of closely- packed teeth are small in size. In such cases as the Eagle- Ray (Myliobatis aquila) (fig. 371) the teeth are broadened out 9o THE FOOD OF ANIMALS into six-sided plates, united along their edges, and forming a sort of pavement well suited for crushing purposes. In some of Fig. 371. — Eagle Ray (Myliobatis aquila) the allied species there is an arrangement supposed to compensate for the inconvenient position of the mouth, which is not only placed far back on the under side, but also, owing to the flattening of the body, does not extend to the sides. The specialization in question consists of a horn-like projection on either side formed from a part of the pectoral fin. These horns are supposed to play the part of hands, and convey food to the mouth. Some of the Rays, however, are enabled by special devices to prey upon fishes capable of much swifter movement than they are themselves. The colour and markings of the upper surface, for instance, may be such as to bring about so close a resemblance to the adjacent sea-bottom that other fishes venture within reach; and, fur- ther, some Rays have slender tails provided with sharp spines, enabling them to seize and wound their prey (fig. 371). The Electric Rays (fig. 372), of which a common type is the marbled species (Torpedo marmorata), are Fig. 372.— Electric Ray (Torpedo) FISHES provided with electric organs, by which other fishes may be killed or rendered powerless. ROUND-MOUTHS (CYCLOSTOMES) The lowest Vertebrates which have any claim to be included among the fishes are the Round- Mouths or Cyclostomes, including the Lampreys and Hags, which have a wide distribution in both hemispheres. They are eel-like creatures, remarkable for the absence of a lower jaw, so that they are unable to bite in the ordinary sense of the word. Notwithstanding this, they are essentially carnivorous in habit, and prey upon other fishes. If, for example, we examine the common fresh -water Lampern (Petromyzon fluviatilis) (see vol. i, p. 291), or the larger Sea Lamprey (P. marinus), we shall find that the mouth opens in the middle of a large bell-shaped sucker, studded with horny teeth. A muscular projection, the tongue, also provided with powerful teeth, can be alternately protruded from and withdrawn into the TONGUE Fig- 373-— Suctorial Mouth of Lamprey (Petromyzon) Fig. 374. — Hag- Fish (Myxine glutinosa) mouth. The sucker is firmly attached to the prey, and the tongue is then used as a rasp for scraping away parts of the flesh (fig. 373). Still more specialized is the Hag- Fish (Myxine glutinosct) (fig. 374), in which the degenerate and useless eyes are sunk 92 THE FOOD OF ANIMALS below the skin, and which possesses the unpleasant property of secreting enormous quantities of slime by means of the glandular skin. This creature is able actually to bore into the bodies of other fishes, though the common idea that a cod can swim about with a hag-fish half-imbedded in it rests on slender foundation. The fact appears to be that when cod are caught on deep-sea lines they are often attacked by the hag, which bores some distance into them before they are pulled up. PRIMITIVE VERTEBRATES The lowly Vertebrates, or more properly speaking Chordates, wnich are inferior in the scale to Fishes, feed to a large extent on animal matter, but as their diet is also in part of plant nature it will be best to leave them till omnivorous forms are described. CHAPTER VIII THE FOOD OF ANIMALS— NEMERTINES AND CARNIVOROUS MOLLUSCS Having briefly dealt with Vertebrates, we now proceed to the consideration of the food and feeding habits of carnivorous Inver- tebrates, beginning with NEMERTINES, and taking next the great phylum of MOLLUSCA. NEMERTINES These curious worm-like marine forms, which have been de- scribed elsewhere as regards their structure (see vol. i p. 306), are purely carnivorous, preying upon all sorts of creatures, both alive and dead. The mouth and front part of the digestive tube are capable of a large amount of dilatation, enabling com- paratively large bodies to be swallowed with ease. The most remarkable peculiarity of these animals is the possession of a long tubular ' ' proboscis ", which, when not in use, is con- tained in a sheath running along the upper side of the body, from which it can be shot out with great rapidity through a small hole situ- ated in most cases in front of the mouth, though sometimes placed within it. The proboscis appears to be used for seizing food, and in a large number of forms its tip is provided with a sharp stylet, at the base of which poison- glands open (fig. 375). This is probably to be regarded as a means of overpowering prey. hd. Fig. 375.— Front End of Nemertine, with proboscis partly protruded. Seen from above (diagrammatic) hd, Head ; pr, proboscis ; st, stylet ; r.st, one of the two sacs containing reserve stylets; p.gl., poison-gland; r. m. , retractor muscle. 94 THE FOOD OF ANIMALS CARNIVOROUS MOLLUSCS CUTTLE-FISHES AND SQUIDS (CEPHALOPODS) The members of the highest class of Molluscs, the head-footed creatures embraced under the term Cephalopoda, are essentially rapacious, and typical in this respect are the Cuttle- Fish (Sepia ojficinalis), the Squid (Loligo vulgaris], the Octopus or Poulpe (Octopus vulgaris], and the Musky Octopus (Eledone moschatus]. In the absence of limbs these creatures possess very effective weapons of offence, formed by modification of a part of the typical molluscan organ known as the foot, and which in its simplest form, as seen in a common snail, consists of a muscular outgrowth from the under side of the body, presenting a creeping sole-like surface. In the case of, say, a cuttle-fish, the front part of this foot has grown round and fused with the head, hence the name head-footed molluscs. And this region is drawn out into a number of slender arms capable of being stretched out till they look like whip-lashes, there being eight of them in an octopus and ten in a cuttle-fish. In the latter, two of the arms are much longer than the rest and expanded at their ends, while they can also be drawn back into special pouches. The mouth of the animal is situated between the bases of these arms. (See vol. i, fig. 179.) Not only are the arms extremely extensible and capable of being twined around any animal attacked, but they are studded on their inner sides with suckers (stalked in cuttle-fishes, unstalked in octopi), by means of which a most tenacious grip is maintained. Each sucker is a little cup, the margin of which is provided with a toothed horny ring for the prevention of slipping, and within which is a muscular projection that can be drawn back piston-like so as to produce a vacuum. After being seized by the arms the prey is drawn to the mouth, which is furnished with a pair of strong horny jaws closely resembling the beak of a parrot (fig. 376). After this has fixed itself firmly to the body of the animal the rasping organ is brought into action, and this structure is so important that it merits a somewhat detailed description. A rasping organ, or, to use the technical term, odontophore (Gk., odous, odontos, tooth; phero, I bear), is eminently character- istic of all the Mollusca, with the exception of the bivalve forms, and is just as useful to the vegetarians as to the carnivorous CARNIVOROUS MOLLUSCS 95 species. It consists of (vol. i, fig. 199) a cushion rising up from the floor of the mouth, and supported by hard parts of a gristly nature. Stretched over this swelling from front to back is a horny ribbon-shaped structure, the radula (L. radula, a scraper), the surface of which is beset with regular rows of small, sharp, horny teeth. By means of appropriate muscles the odontophore can be somewhat protruded, so as to press against the object to Fig. 376.— Beaks of Cuttle-Fish (Sepia officinalis) A, From below (the radula on its cushion is seen within). B, From the side, c, Lower beak. D, Upper beak. be rasped, and there are also muscles by which it can be drawn back again and put out of action when required. Within the cushion of the odontophore are other small muscles for working the radula (which rests loosely upon its support) backwards and forwards, after the manner of a chain-saw, so as to rasp very effectively anything to which it may be applied. The gristly supports of the odontophore give points of attachment to these little muscles. After a certain amount of work the teeth of the radula become blunt and worn, but this contingency is provided for, as the ribbon is continually growing forwards, much like a finger-nail. And just as by gently moving a finger-nail up and down you can see that it runs back under a fold of skin to a " root " where new nail is constantly being formed, so can the radula be followed back into a projection, the radula sac, out of which it is continually growing. This toothed ribbon, which con- stitutes the actual scraping part of the odontophore, is often called 96 THE FOOD OF ANIMALS the "tongue" or "palate", and will usually be found described as such in catalogues of microscopic objects. It is of importance in classification, for the teeth vary in number, nature, and arrange- ment in different species. SNAILS AND SLUGS (GASTROPODA) From Cephalopods we pass on to the enormous group of Snails and Slugs, i.e. to the Gastropoda, of which vast numbers are carnivorous. It is interesting to note that by cursory inspec- tion of the empty shell it is pos- sible to tell whether the inhabi- tant subsisted on animal or vege- table matter, for in the former case the opening or mouth is notched, in the latter continuous or entire. The notch is for the protrusion of a tubular organ (the siphon) related to the breath- ing function, and which will be described in a subsequent section. Fig. 377.-A single row of Teeth from radulae of Carni- The tCCth in the radula of a Car- vorous Snails (greatly enlarged) A, From Glandina (a land-snail). B, From Whelk HlVOrOUS gastropod are USUally (Bncctnum undatum). On the right is shown the entire comparatively fe W and Specialized, radula (natural size). ' « Their form is often strongly curved, or it may be hook-like (fig. 377). One of the commonest and most voracious inhabitants of the zone between tide-marks round the British coasts is the Purple- Shell (Purpura lapillus] (fig. 378). This is possessed of a pro- trusible snout, armed with a strong odontophore, and it plays havoc with other Gastropods and with Bivalves, especially mussels, These may either be attacked through the opening of the shell, or, failing this easy path, the Purple -Shell bores through the firm investment of its prey. One commonly picks up the loose shells of small bivalves in which a neat round hole has been drilled, and as often as not this has been the work of a Purpura. These snails may also be found crawling about projecting rocks studded with acorn barnacles, the firm shells of which they per- forate in much the same way and with the same object in view, and a little careful observation will often result in the detection CARNIVOROUS MOLLUSCS 97 of the aggressors actually at work. The rasping noise made by the radula as it bores through the barnacle's shell is readily audible. Fig. 378. — The Purple-Shell (Purpura lapillus}. The small figure shows an individual crawling. Another common carnivorous sea-snail, much larger than the Purple- Shell, and rapacious in proportion to its size, is the Common Whelk (Buccinum undatum) (see vol. i, p. 321), abundant in shallow water. The rasping apparatus is lodged in the tip of a very long narrow proboscis, which can either be protruded or drawn completely back into the body. Whelks chiefly prey upon bivalve molluscs, even some of the burrowing species not being exempt from its attacks, and it is one of the many enemies of the oyster. The Cone -Shells, most of which are tropical, are interesting in the present connection because the bite is poisonous in some, perhaps all, of the species (fig. 379). That any sort of sea-snail should bite a human being seems at first sight somewhat singular, but Cone -Shells, when incautiously handled, have done so, and this led to the discovery that some of these forms are poisonous. Method of Shell-boring. — Such molluscs as the Purple- Shell, Whelk, &c., are commonly supposed to depend entirely on the radula as a means of penetrating the shells of their victims. It certainly does assist in the process (see above — Purple- g. 379 Barbed Poison-tooth from radula of a Cone. At the base is seen the poi- son-gland, the duct of which runs within the tooth and opens near its tip. VOL. II. 98 THE FOOD OF ANIMALS ...a Fig 380. — A boring carnivorous Sea-Snail (Natica Josephina) The front of the foot is folded back, and above it is seen the projecting snout with boring organ (a). Shell). Unaided, however, this structure does not seem powerful enough for the purpose, and even if it were, it is difficult to see how a ribbon-shaped organ could be employed to bore a round hole. The matter has been carefully investigated (by Schiemenz) in a species of Natica (N. Jose- phina] (fig. 380), a sea -snail possessed of a very large foot, by means of which it burrows in the -sand in pursuit of the bivalves upon which it chiefly feeds, and which are commonly found buried in an oblique position, with the posterior end projecting at the surface. The Natica appears to detect its prey by means of the sensi- tive front-end of its foot, which is then folded back so as not to interfere with the action of the proboscis, and at the same time co-operates with the rest of the foot in grasping firmly the front end of the unfortunate bivalve. The proboscis is now protruded, and close to the under side of its tip the true boring organ is seen as a circular disc, upon the surface of which a large number of little glands open. This structure is applied to the shell to be per- forated, and an acid fluid is poured out from it which dissolves the shell over a small circular area of corresponding size and shape. As soon as a hole has been made, it would seem that the radula helps to enlarge it, and is afterwards used for rasping the flesh of the prey through the breach made in its defences (fig. 381). The exact mode of procedure in Whelk, Purple- Shell, &c., has not yet been determined, but there is little doubt that an acid secretion is brought into play. It is well known that the so-called salivary glands of a number of the predaceous sea-snails contain an ap- preciable quantity of free sulphuric acid, and it is suggested that Fig. 381.— Bivalve Shells bored by Natica CARNIVOROUS MOLLUSCS 99 this is used to eat away the shells of the molluscs, &c., attacked by such creatures. This is a good example of the numerous cases where our knowledge of the habits of common animals is woe- fully incomplete, and is just the kind of problem which might be attacked with fair chance of success by local natu- ral history clubs, given patience and the power of accurately observing details. Most profes- sional zoologists, unfor- tunately, are too much taken up with labora- tory work to attend to such matters, though the study of animal ha- bits is perhaps the most interesting branch of their subject. Fig. 382.— Heteropods A, Atlanta: i, snout; 2, foot; 3, operculum; 4, shell. B, Pterotrachea: i, gills; 2, foot; 3, snout. These creatures swim upside down as represented. HETEROPODS. — Among predaceous Gastropods are the free- swimming marine forms known as Heteropods (fig. 382), in which the foot is more or less completely transformed into a fin, by means of which the animal swims with its upper surface directed downwards. Like animals of pelagic habit generally they are of almost glass-like transparency, and may or may not be provided with a shell. Atlanta, for example, has a spiral shell, Carinaria a cap-shaped one, and Pterotrachea none at all. They possess a long snout, in the end of which the rasping organ is ioo THE FOOD OF ANIMALS lodged, and prey upon jelly-fish and other floating forms with which they are associated on the high seas. TECTIBRANCHS. — So far examples have been given of thefore- gilled Gastropods only, but carnivorous types are found among the hind-gilled subdivision as well. The Tectibranch members of the group are provided with a shell, though this may in some cases be a mere plate sunk below the surface to a greater or less extent. The burrowing form, Scaphander, is a good example of quite a different mode of procedure • from that adopted by whelk, &c., for instead of boring holes in the shells of compara- tively large animals, it selects for its prey small molluscs and the like, which can be conveniently swallowed whole, after which they are crushed by the action of a powerful gizzard armed with firm calcareous plates. Similar in habit and structure are the Bubble- Shells (see vol. i, p. 324); and so is one of the most abundant British Tectibranchs, Philine aperta, a little white creature with its delicate shell completely hidden from view, and which feeds very largely upon Foraminifera. SEA-SLUGS (Nudibranchs). — Some of the Sea-Slugs, consti- tuting the shell-less Nudibranch section of the hind-gilled group, are also flesh- eaters. An instance is ^Eolidia, in which the body is studded with tentacle-like outgrowths, and which chiefly attacks soft creatures like sea-anemones. It is not uncommon between tide-marks on some parts of our coast. A related genus, Glaucus, is of a beautiful blue tint, and drifts about in the open sea attached to sea- weed. It preys upon jelly-fish and the like. LUNG- SNAILS (Pulmonates). — Though most of the lung-breath- ing Gastropods, including the land-snails and slugs, as well as some of the freshwater snails, feed upon vegetable substances, there are some kinds which are exclusively carnivorous. Among these may be mentioned certain slugs belonging to the genus Testacella, in which there is a small cup-shaped shell borne on the tip of the tail. These creatures are among the many enemies of earth-worms, which they pursue underground. BRITISH SEA-SLUGS (Nudibranchs} (After Alder and Hancock.) Drawn to various scales These beautiful little creeping Molluscs are devoid of shells, nor do they possess the typical gill-chamber with gills characteristic of their allies the Sea-Snails. Some, however, are provided with a circlet of feather-like breathing-organs surrounding the intestinal aperture (see i, 2, 4). Together with (see i and 2), or in the absence of these (see 3 and 5), there may be a varying number of simple or branching outgrowths (cerata) from the upper side of the body, which are provided with defensive stinging-organs. Nudibranchs are either coloured so as to harmonize with their surroundings ("general protective coloration"), or in such a way as to make them very conspicuous (" warning coloration "). The latter state of things advertises unpleasant properties by way of smell or taste, and gives a certain amount of protection against fishes, &c. 1. Triopa clavtger. 2. Thecacera pennigera. 3. Eolis coronata. 4. Doris coccinea. 5. Doto coronata. V BRITISH SEA-SLUGS (NUDiBRANCHS) i. Triopa claviger. 2. Thecacera pennigera. 3. Eolis coronata. 4. Doris cocci nea. 5. Doto coronata. CHAPTER IX THE FOOD OF ANIMALS— CARNIVOROUS INSECTS The huge phylum of ARTHROPODA embraces an extraordinary variety of forms adapted to life under the most diverse conditions, and frequently of carnivorous habit. The most characteristic feature in all these animals is the possession of paired, jointed limbs, specialized for the performance of various functions. Some are used in locomotion, others serve as weapons of offence and defence, and others again act as jaws. The nervous system and sense organs are exceedingly well developed, and this is asso- ciated with extreme activity and, in certain cases, with intelligence of a high order. Arthropods are divided into two great groups — one of AIR- BREATHERS (Tracheata), including Insects, Scorpions (and their allies), Centipedes and Millipedes, and the primitive form Peri- patus; the other of aquatic GILL-BEARING FORMS (Branchiata), embracing Crustacea and their allies. It will be convenient to begin with Insects and finish with Crustacea. INSECTS (INSECTA) Insects include the large majority of land animals, and of all terrestrial invertebrate groups have been most successful in the struggle for existence. This no doubt results from their great activity, which in its turn is dependent upon very perfect arrange- ments for purifying the blood and introducing fresh oxygen into the system. Nor must it be forgotten that most members of the class are endowed with the power of flight, which is in itself a great advantage, especially in the search for suitable food. The possession of this power largely accounts for the wide distribution of the group. A simple and typical insect, the Cockroach, has been described at some length in vol. i, p. 343, and it is not necessary to repeat much of what was there said, though a few of the more salient points may with advantage be reviewed. The body of an insect is clearly divided into three distinct regions: 101 102 THE FOOD OF ANIMALS (1) the head, provided with feelers (antennae), eyes, and other sense organs, and bearing three pairs of limbs specialized as jaws ; (2) the thorax, carrying three pairs of legs and two pairs of wings; and (3) the abdomen, devoid of obvious limbs, though modified traces of these are usually present at the hinder end. For our present purpose the jaws merit special attention. They are known as mandibles, first maxillae, and second maxillae, when taken in order from front to back, and are clustered together in the neigh- bourhood of the mouth-opening, the first pair of them being overlapped by the second, and these again by the third. In the Cockroach they are in a comparatively simple condition: the mandibles are strong, horny jaws adapted for biting; the first maxillae are also provided with cutting pieces; and the second maxillae are partly fused into a sort of plate which acts as an under lip, or labium as it is often called. Jointed feelers or palps are borne by both pairs of maxillae, and are termed respectively maxillary palps and labial palps. It should further be remarked that a broad upper lip or labrum overhangs the mouth in front, and the mandibles and first maxillae work from side to side in the space between upper and lower lips, effectively biting anything that may happen to be between them. An insect with jaws of the sort just described is said to have biting mouth-parts; but in other cases the corresponding parts may be specialized into sucking, licking, or piercing organs, as will be shown in the sequel. Indeed, the mouth-parts of insects afford one of the best -known illustrations of modifications for special purposes based on a common type or plan of structure, a principle which frequently recurs in the animal kingdom. The nine orders of Insects may roughly be divided into two sets, according as the mouth-parts are suited for biting or modified into suctorial structures. A. — Insects with biting mouth-parts (in the adult). 1. MEMBRANE-WINGED INSECTS (HYMENOPTERA).— Bees, Wasps, Ants, &c. 2. BEETLES (COLEOPTERA). 3. NET-WINGED INSECTS (NEUROPTERA). — Dragon-Flies, Termites, May-Flies, &c. 4. STRAIGHT-WINGED INSECTS (ORTHOPTERA).— Cockroaches, Crickets, Locusts, Grasshoppers, Earwigs. 5. WINGLESS INSECTS (APTERA). — Primitive forms, in some of which the mouth may be imperfectly suctorial. CARNIVOROUS INSECTS 103 B. — Mouth more or less perfectly suctorial (in the adult). 6. MOTHS AND BUTTERFLIES (LEPIDOPTERA). 7. FLIES AND FLEAS (DIPTERA). 8. FRINGED-WINGED INSECTS (THYSANOPTERA). — Corn-Thrips, &c. 9. BUGS (HEMIPTERA). The above grouping is founded on the structure of the mouth- parts in the adult, but these may be quite different in the larva, in correlation with different habits. A caterpillar, for example, has biting mouth-parts, but the corresponding organs of the moth or butterfly into which it ultimately develops are purely suctorial. MEMBRANE-WINGED INSECTS (HYMENOPTERA) This order is regarded by many authorities as the highest among insects, not so much perhaps on the ground of complexity of structure as on the score of a marvellously-developed intelli- gence, seen more particularly in the social species of ant, bee, and wasp. Details relating to the social economy of such forms will be given in another connection, when the association of animals is considered ; here we are only concerned with the question of food. Ordinary British species are omnivorous in habit, but certain tropical forms show a marked predilection for animal food, and some of them migrate from place to place in formidable armies which make a clean sweep of everything that comes in their way. PREDACEOUS ANTS. — This is the case, for instance, with the much-dreaded Driver- Ants (Anomma arcens) of West Africa, regarding which not a few unpleasant stories are current, such as the reported tying-up of criminals in their path and so forth. Their habits have been described by Savage, who states that they check " the more rapid increase of noxious insects and smaller reptiles; consume much dead animal matter, which is constantly occurring, decaying, becoming offensive, and thus vitiating the atmosphere, and, which is by no means the least important in the Torrid Zone, often compelling the inhabitants to keep their dwellings, towns, and their vicinity in a state of comparative cleanliness. The dread of them is upon every living thing0 . . . Their entrance into a house is soon known by the simultaneous and universal movement of rats, mice, lizards, Blapsidae, Blattidae, and of the numerous vermin that infest our dwellings." These 104 THE FOOD OF ANIMALS Driver-Ants are blind and do most of their hunting at night. Bates (in The Naturalist on the River Amazons] has graphically described the somewhat similar habits of certain South American Fig. 383. — Foraging- Ants (Eciton hamata] on the march Foraging-Ants belonging to the genus Eciton (fig. 383). As in so many other insect communities there are here not only males and females but also " workers ", in this case of two kinds, large - heads and small - heads, the former being possessed of particularly powerful mandibles, styled simply "jaws" in most CARNIVOROUS INSECTS 105 works on natural history. It should further be noted that in most ants, as also in bees and wasps, the females and workers (which are really undeveloped females) possess a poisonous sting in the hinder-part of the body. This consists essentially of a couple of slender-toothed stylets, enclosed in a sheath, and connected with a poison-gland, of which the secretion contains formic acid, a substance which indeed owes its name to the fact that ants are the source from which it was first derived (Lat. formica, an ant). Bates speaks as follows of the two commonest species of these Foraging- Ants (Eciton hamata and E. drepanopkora): — " These Ecitons are seen in the pathways of the forest at all places on the banks of the Amazons, travelling in dense columns of countless thousands. . . . When the pedestrian falls in with a train of these ants, the first signal given him is a twittering and restless move- ment of small flocks of plain-coloured birds (ant-thrushes) in the jungle. If this be disregarded until he advances a few steps farther, he is sure to fall into trouble, and find himself suddenly attacked by numbers of the ferocious little creatures. They swarm up his legs with incredible rapidity, each one driving its pincer-like jaws into his skin, and with the purchase thus obtained, doubling its tail, and stinging with all its might. . . . The errand of the vast ant-armies is plunder. . . . Wherever they move, the whole animal world is set in commotion, and every creature tries to get out of their way. But it is especially the various tribes of wingless insects [and other arthropods] that have cause for fear, such as heavy-bodied spiders, ants of other species, maggots, caterpillars, larvae of cockroaches, and so forth, all of which live under fallen leaves or in decaying wood. The Ecitons do not mount very high on trees, and therefore the nestlings of birds are not much incommoded by them. The mode of operation of these armies, which I ascertained only after long-continued observation, is as follows: — The main column, from four to six deep, moves forward in a given direction, clearing the ground of all animal matter, dead or alive, and throwing off here and there a thinner column to forage for a short time on the flanks of the main army, and re-enter it again after their task is accomplished. If some very rich place be encountered anywhere near the line of march, for example a mass of rotten wood abounding in insect larvae, a delay takes place, and a very strong force of ants is concentrated upon it. The excited creatures search every cranny, and tear in pieces io6 THE FOOD OF ANIMALS all the large grubs they drag to light." The same naturalist gives an account of certain blind species of these ants which construct covered roads from grains of earth, under which they march to suitable hunting grounds. For further details on this fascinating subject the original work must be consulted. Besides predaceous social ants there are also solitary ones of similar habit, some of these being British (as, e.g., Mutilla Europcect). SAND-WASPS. — There are many hymenopterous insects which provide a store of suitable food for their carnivorous young, Fig. 384.— Bird -catching Spider (My gale] threatened by a Sand-Wasp (Pepsis] a subject which will be entered into more fully later on when the care of young is under consideration. It will suffice to say here that -Sand- Wasps, solitary insects of various species, lay their eggs in holes in the ground or elsewhere, sometimes digging these out themselves, and drag into these holes caterpillars, adult insects, or spiders, previously stinging them in the nerve- cord so as to paralyse but not kill them. Different species of wasp select different victims for the purpose. The Common Sand- Wasp (Ammophila sabulosa) prefers caterpillars, the Path- Wasp (Pompilus viaticus) spiders, and the Field Sand -Wasp (Mellinus arvensis) flies. Fig. 384 represents a huge South American spider (Mygale) threatened by a large wasp (species of Pepsis] of this kind. CARNIVOROUS INSECTS 107 ICHNEUMON -FLIES. — The provision made for their young by the large group of Ichneumon- Flies is still more remarkable, for in this case the female deposits her eggs in the bodies of insect-larvae, especially caterpillars. When these eggs hatch out, an abundant food-supply surrounds them, in the form of the stores of reserve material which are laid up for use when the adult stage is gradually being shaped in the chrysalis. BEETLES (COLEOPTERA) A large number of Beetles are carnivorous in habit, and in none of them is this more strikingly the case than in the Tiger- Beetles (see vol. i, p. 367), of which the commonest British species is the Field Tiger- Beetle (Cicindela campestris). This is an extremely active insect, which can run with great rapidity, and is possessed of considerable powers of flight. As is usually the case in predaceous animals, the organs of sense are well developed. The most characteristic structures present are the mouth organs, which are obviously constructed on the same type as already described for Cockroach (p. 102). The mandibles, however, are slender but powerful-curved blades, the inner edges of which present a series of sharp projecting teeth, and the biting -pieces of the first maxillae are studded with strong bristles, while each of them ends in a movable claw. The second maxillae are much more closely fused into a lower lip than is the case in the Cock- roach. These beetles are extremely fierce, and have even been known to indulge in cannibalism. Staveley says (in British Insects): — ''The female has often been seen to deliberately dis- member and eat her husband, though it remains a puzzle to naturalists that the husband — an insect apparently equal to herself, or nearly so, in size and power — should submit to this ". The larva of the Tiger- Beetle is also predaceous, lurking in a vertical burrow in the ground, and attacking small insects which happen to pass. GROUND -BEETLES. — Most of the Ground -Beetles (Carabida) are carnivorous, and these include an enormous number of species scattered all over the globe. The Violet Ground- Beetle (Carabus violaceus) is often found in houses, where it preys upon crickets and cockroaches. It is nocturnal in habit, unlike the Tiger-beetle, which hunts its prey during the day. Some of the Ground- Beetles excavate burrows, at the mouths of which they wait for prey. io8 THE FOOD OF ANIMALS ROVE- BEETLES. — The Rove- Beetles (Staphylinidce) constitute another very large universally-distributed family of carnivorous beetles, with slender elongated bodies and short wing-cases. A Fig. 385. — Newts and Fresh-water Insects, i, Great Water-Beetle (Dytiscus marginalis) 2, Water-Scorpions (Nepa cinerea) familiar native species is the Devil's Coach- Horse (Ocypus olens) (see vol. i, p. 368), which, like most of its kind, turns up the tip of its tail when interfered with. WATER- BEETLES (fig. 385). — Some of the flesh-eating beetles live in fresh water, and among these is the Great Water- Beetle CARNIVOROUS INSECTS 109 (Dytiscus marginalis), which preys not only upon invertebrates but also upon tadpoles, newts, and small fishes. The ugly broad- headed larva is to the full as predatory as the adult, and its dull colour harmonizes with the mud on which it lives, and renders it inconspicuous to its prey. The long curved mandibles are grooved for the purpose of conducting the juices of the prey to Fig. 386. — Scavenging Beetles i and 2, Burying-Beetles (Necrophorus Germanica and N. vespillo). 3 and 4, Adult and larva of black Carrion- Beetle (Silpha atrata}. 5, Maggot-eating Beetle (Hister quadrinotatus}. 6, Bacon-Beetle (Dermestes lardarius). the creature's mouth. A still larger aquatic insect than the one just described is the Great Black Water- Beetle (Hydrophilus piceus], which belongs to a different family, and is interesting because it is one of the many cases in which the adult and larva differ as to the nature of the food. Here the latter is active and carnivorous, while the adult beetle feeds on vegetable matter, and in correlation with this is comparatively sluggish in its move- ments. LADY- BIRDS. — The last predaceous beetles to be mentioned here are the pretty little Lady- Birds (Coccinella) (see vol. i, p. 366), which wage perpetual war upon plant-lice (aphides), more com- no THE FOOD OF ANIMALS monly known perhaps as " green fly". The larvae of these beetles affect the same diet as their parents. They are bristly- looking creatures of bluish -grey colour flecked with yellowish spots. SCAVENGING- BEETLES (fig. 386). — Several families of Beetles include species which either in the adult or larval stage, or in both, feed upon decaying animal matter, or upon skins, food of animal origin, &c. Of these perhaps the most remarkable are the Carrion- Beetles (Silpkida), among which the Burying- Beetles (species of Necrophorus) are well known from their habit of burying the carcasses of small mammals, birds, &c., from under which they excavate the earth, afterwards covering them over. Their eggs are laid in this carrion, which furnishes an abundant supply of savoury food to the larvae. To the same family belong the Rove Carrion- Beetles (species of Silpha), of which the larvae live, in many species, upon decaying animal matter. The members of another family (Histeridae) were formerly supposed to feed upon the decaying matter among which they live, but it appears that this is not really the case, both adult insects and their larvae being of predaceous habit, and preying upon fly -maggots and the like. The larvae of one widely -distributed family of beetles (Dermestidae) feed mainly on dried animal matter, and are found in skins, fur, and even horse-hair, while in the Bacon- Beetle (Dermestes lardarius] they are found in different sorts of animal food. NET-WINGED INSECTS (NEUROPTERA) A large number of the insects contained in this heterogeneous and extensive order are predaceous in habit, and in such cases tl>e larvae, which in many groups are aquatic, rival or excel the adults in their bloodthirsty tendencies. Among the most im- portant members of the order living on land throughout their entire existence are the Termites and Biting- Lice. Termites, popularly known as White -" ants ", will be dealt with later on, when social insects are described, and in any case only need passing mention here, since wood is the staple of their diet, though they are also more or less given to cannibalism. BITING- LICE are small wingless insects, living as external parasites on the bodies of mammals and, more especially, on birds (whence the name of " bird-lice " is commonly given to CARNIVOROUS INSECTS in them). The strong mandibles are provided with sharp teeth, and are well adapted for cutting pieces off the young feathers and other epidermal products on which these creatures subsist. They are quite distinct from true blood-sucking lice, which have piercing mouth-parts and' belong to the order Hemiptera (Bugs, &c.). Some five different species infest fowls, the commonest being the Pale Poultry- Louse (Menopon pallidum). Everyone must have noticed poultry taking "dust baths", the object of which is to get rid of some of these parasites. The SNAKE- FLIES (see vol. i, p. 375), remarkable for the possession of a long neck, feed upon various small insects, and their heads are freely movable so as to enable them the more readily to seize their prey. The elongated larva is extremely active and possessed of an unbounded appetite. It lives in rotten wood, relentlessly hunting down other insects which have the same habitat. SCORPION-FLIES (see vol. i, p. 375) constitute a small group in which both the adults and the spiny terrestrial larvae are carnivorous. The elongated head is provided with strong, toothed mandibles. One of the European species (Bittacus tipularius) is particularly interesting, for it resembles a " daddy-long-legs ", which no doubt allays the suspicions of the small flies upon which it feeds. Should one of these approach too near, it is liable to be captured by the hooked hind-legs of the apparently harmless insect, which meanwhile holds on to a plant by means of its two •other pairs of elongated limbs. ANT-LIONS. — One of the most notable insects in the whole order of Neuroptera is the Ant -Lion (Myrmeleo formicarius) {fig. 387), a common European form which has been the subject of observation for some two centuries. The chief interest attached to this creature centres in the backwardly-walking larva, to which stage the name " ant-lion" is properly applied. Its appearance is characteristic, and not calculated to inspire confidence in weaker insects, but this does not matter, as it is a case where the battle is to the "slim" rather than the swift. The powerful head is provided with enormously-developed curved mandibles, the stout thorax bears powerful legs, and the elongated abdomen is of oval shape. The ingenious method of hunting adopted in this case consists in the digging of a pitfall by the larva, which then lurks at the bottom of it. The insect navvy does not begin 112 THE FOOD OF ANIMALS excavating at the centre, but commences operations by construct- ing a groove to correspond with the margin of the proposed pit. Fig. 387. — The Ant-Lion (Myrmeleoformicarius}. Perfect Insect, and Larva with its Pit Then it buries its abdomen in the sand, heaps some of the loose material on its head by means of the fore-legs, and pitches it off with a jerk to some little distance. The meaning of the CARNIVOROUS INSECTS broad strong head is therefore at once apparent. After going all round in this fashion it moves inwards and works on a narrower circle, and so goes on till a conical pit is excavated, at the bottom of which it buries itself, the front part of the head only projecting. If now an unfortunate fly, or, still better, an ant, steps over the margin of the trap, it will begin to lose foot- hold, sliding gradually downwards, the descent being rendered still more easy by the ingenious ant-lion, which pitches sand on the prospective meal. Once seized by the aggressive -looking mandibles there is no chance of escape, for a special arrange- ment exists by which the juices of the prey can be sucked with- out any necessity for leaving go. The beginning of the food- tube is in the form of a muscular suction-pump to which a groove on the under side of each mandible leads, and in this groove the long and slender first maxilla of the same side works back and fore like a piston. After finishing its meal the bloodthirsty larva pitches the shrivelled remains of its victim to some distance, partly, perhaps, for sanitary reasons, and it may be to prevent other available wayfarers from taking alarm. It is interesting to note that certain cousins of the Ant- Lion, though similar in appearance, do not dig pit- falls. These, however, are active in their habits and pro- gress in the usual direction, forward and not backward. It is supposed that they remain in ambush, hidden in dark corners, rushing out when a favourable opportunity offers. MANTIS-LIKE NET- WINGS. —Equally interesting, though less familiar than the Ant- Lion, are the Mantis-like Net- Wings (Mantispides] (fig. 388), constituting a small group of which the species are mostly found in the hotter parts of the globe, though some are natives of South Europe. The great peculiarity of the adult insect consists in the structure of the strong fore-legs, which, as in the praying mantis, &c., among the Orthoptera, are attached close to the head and specialized into a very effective fly-trap. The middle section of each leg is studded with strong Fig. 388.— Mantis Net-Wing (Mantispides] VOL. II. 40 ii4 THE FOOD OF ANIMALS spines, and the end-part of the limb can be folded down on these, much as the blade of a pocket-knife shuts down on the handle, so as to form a grasping structure well suited for seizing and holding active prey. The habits of the larva, which when first. hatched is a slender creature much like some of the aquatic larvae mentioned earlier, have been described for one of the European species (Mantispes Styriaca). At the time when it makes its appearance certain spiders (of the genus Lycosa) have laid their eggs, enclosed in little bags. One such bag is sought out by each larva, which bites a hole in it, creeps in, and patiently waits among the developing eggs till they hatch out into juicy little spiders, the sad fate of which is to be either at once devoured or else killed and reserved for future use. After a time the larva sheds its skin and becomes a sluggish grub-like creature, which, after making many hearty meals on the reserve spiders, passes through further stages, which result in the appearance of the adult form. The LACE-WING FLIES (Hemerobiidce and Ckrysopida) are small fragile insects of common occurrence in Britain, and interesting on account of the habits of their larvae, which prey chiefly on aphides ("green fly"). The long slender mandibles may be described as " sucking spears", and are used for piercing the tender bodies of the prey, from which the juices are extracted much as in the case of the ant - lion. Some of these larvae (Hemerobius, certain species of Chrysopa), which, by the bye, have appropriately been termed " aphis-lions ", convert themselves into walking cemeteries by covering their spiny bodies with the shrivelled carcasses of their prey, a bold expedient for making them inconspicuous, others (some species of Chrysopa] use frag- ments of vegetable matter for the same purpose, while others again (most species of Chrysopa] resort to neither of these devices but prowl about unprotected. The Golden-eyed Flies (Chrysopa) (see vol. i, p. 378) are common British members of the group. DRAGON-FLIES (see vol. i, p. 375). — In most of the neurop- terous insects remaining to be mentioned here the larvae are aquatic in habit. Among the most familiar and attractive of these are the Dragon- Flies, distinguished by their great powers of flight and very perfectly-developed sense organs, the compound eyes being of relatively enormous size. Like bats and swallows, they catch insects on the wing, and may often be seen hawking CARNIVOROUS INSECTS 115 for them in country lanes and above the surface of ponds. The legs of a Dragon- Fly are set on very far forwards, and this is believed to be related to one of their functions. Just as some bats use part of their flying membranes as a kind of sweep-net for securing insects on the wing, so wrould it appear that the dragon-fly's legs are forwardly directed during flight, acting as a sort of fly-trap, the efficiency of which is increased by the presence of numerous minute spines. Once entangled in this trap there is no hope of escape, for the aggressor brings his well- developed mouth-parts into play and conducts further operations, which result in the rejection of the wings and other inedible parts of the prey, and the retention of its more succulent portions for food. These acts are facilitated by the mobility of the dragon-fly's head, and the structure of its mouth-parts, " which include a freely-movable upper lip, and a lower lip provided with two broad plates bounding on the under side the space within which the powerful mandibles and first maxillae work from side to side. The rapacity of the aquatic larval form is even greater than that of the adult. It is a sluggish, by no means attractive- looking creature, thus described by Fred Smith (in The Boyhood of a Naturalist}: — " And look here, here's the larva of a dragon- fly, a thing I can't help having a perfect horror of; it seems to me to be so truly hideous. It is like the nightmare of a horrible scorpion — I mean the Egyptian thing. Its legs, and glorious body, and wings that are to be, are now indescribably ugly, and as though made of dirty putty." Yet this same object is possessed of a most interesting and curious apparatus, by means of which it traps small crustaceans and any other animals of reasonable size that come near enough. This is the so-called "mask", which is thus named because when not in use it is folded up in front of the face, much in the same way as an old-fashioned carriage- step. It is in reality the much-elongated lower lip, and can be rapidly shot out at the prey, which is seized by a couple of movable spiny projections at its tip, and then drawn back to the well-armed mouth. MAY-FLIES AND STONE-FLIES. — The May-Flies (see vol. i, P- 375) and their allies (Ephemerids] are almost proverbial for the brevity of their existence in the adult condition, though there has been a good deal of exaggeration about this. It is doubtful whether they take any food at all, at any rate the n6 THE FOOD OF ANIMALS mouth-parts are in a very much reduced condition, and jaws may be altogether absent. The aquatic larvae, on the other hand, have a relatively long term of existence. They differ largely in character in different species, and it is only the flattened forms that are exclusively carnivorous. Stone- Flies (Per lido) (see vol. i, p. 375) form a related group of insects in which the mouth-parts of the adult are feeble but the aquatic larvae are carnivorous. The CADDIS- FLIES (Pkryganeida] (see vol. i, p. 375) are insects of moth-like appearance, and in the adult state are not predaceous. The aquatic larvae, known as " caddis - worms '\ build cases for themselves from various materials, and as they are mainly vegetarians would not be mentioned here were it not for the peculiar and interesting habits of one group (Hydropsychida\ in which the larvae are carnivorous, at least in certain cases. They live in fixed dwellings made of sand or little pieces of stone fastened together with silk, and with this same material they construct snares in which small aquatic creatures are entangled. An account has been given of a Brazilian species in which the larvae are found in the rapid parts of small streams, the houses of a number of these, as many as thirty, being placed side by side in a transverse row on top of a stone; there being also in some cases several parallel rows of them. The mouth of each habitation faces up-stream, and ex- pands into a large funnel-shaped "verandah", over which a net of silk is spun. A North American species proceeds in a. somewhat different manner, for it spins a wide-meshed net across, the stems of water-plants, &c., in the neighbourhood of its dwelling, where it lies in wait for any prey that may chance to- be snared. There is another allied group (Rhyacophilides), in which also the larvae inhabit fixed cases, and one case is described where the front-legs are provided with strong forceps, evidently used for seizing prey. STRAIGHT-WINGED INSECTS (ORTHOPTERA) These are insects with typical biting mouth - parts, which have been described in the case of the Cockroach (p. 102). The large majority of the species feed upon vegetable matter, or at most on a mixed diet, but a striking exception to this is afforded by the SOOTHSAYERS or PRAYING INSECTS (Mantida\ These are CARNIVOROUS INSECTS 117 highly predaceous, feeding upon flies and other living insects, while some of the larger kinds are also said to attack small vertebrates. Most of the numerous species inhabit the hotter parts of the globe, throughout which they have a wide distri- bution ; several are found in the Mediterranean countries of Europe, and one ranges as far north as Central France. The most remarkable feature in the structure of these insects is found in the first pair of legs, which are used for the purpose of catching and holding the prey. A similar arrangement has already been described for some of the Neuroptera (p. 114), and it essentially consists in a shifting forward -of the front legs, which are extremely powerful, and so constructed that the end part can be folded back on to the middle section. As both these regions are provided with strong spines an efficient gripping organ is the result. The common European form, known as the Praying Mantis {Mantis religiosa) (fig. 389), is a comparatively simple example of this remarkable group. In colour green or brown, it har- monizes with the surround- ings, and is thus rendered Fig. 389.— Praying Mantis (Mantis religiosa] inconspicuous to its prey (ag- gressive general coloration), an end which is enhanced by its patient waiting attitude with the fore -legs stretched out as if in prayer, a position which has given rise to the popular names and originated many superstitions. Dr. Sharp says (in the Cambridge Natural History]'. — "Some of the older writers went so far as to say that a Mantis would indicate the road a child should take by stretching out one of its arms in the right direction ". Speaking of the group generally the same authority adds :— ' This appearance of innocence and quietness must have struck all who have seen these insects alive; nevertheless, it is of the most deceptive character, for the creature's activity consists of a series of wholesale massacres carried on day after day, the number of victims it sacrifices being enormous. The Mantis does not even spare its own kind; it is well known that the female not infrequently devours its own mate." To do justice to the habits of these interesting insects far more space would u8 THE FOOD OF ANIMALS be required than is here available. Many of the tropical species are remarkable for their curious form and coloration, by which a close resemblance to foliage or flowers is brought about. Nor do all of them wait till prey comes within reach: a species in- habiting New Zealand (though probably introduced from Australia) has been described which is in the habit of stalking its victims till near enough to secure them by a sudden rush. Annandale has recently given a very interesting account of a pink Mantis found in Siam, which will ser^e as a final illustration. This creature is in the habit of stationing itself on the look-out for prey in the midst of groups of pink flowers something like rhododendrons in appearance. The limbs and front part of the body are of the same tint, and so is the under side of the abdomen, which is bent up over the back so as to be in full view. As, however, the insect is too large to be mistaken for part of a single flower, there is a green band which runs across the upper side of the thorax and divides the pink colour into two sections which harmonize with two different blossoms. It may also be added that there is a small black patch at the tip of the abdomen upon which minute flies are in the habit of perching. Being too insignificant to be worth capturing, the Mantis leaves these alone, and their presence adds to the illusion. This, however, is not all, for when the group of flowers withers the Mantis migrates to another, turning down the abdomen so as to display the upper surface, which is marked with brown lines so as to suggest a withering flower. And further, when in this posture, the insect looks very much like an orchis blossom, for the striped abdomen simulates the broad lower petal (labellum), while the limbs, which are broadened out, together with the front part of the body, represent the rest of the orchis. This is a marvellous instance of aggressive special coloration and form, whereby some pre- daceous animals resemble definite objects so closely that their prey is prevented from taking alarm. Passing by the WINGLESS INSECTS (APTERA), which have little- developed mouth-parts, and for the most part are believed to live on disintegrating vegetable matter, we come to carnivorous insects with sucking mouth-parts. CARNIVOROUS INSECTS 119 120 THE FOOD OF ANIMALS MOTHS AND BUTTERFLIES (LEPIDOPTERA) This is essentially a vegetarian order, and, as such, will be described later on. The caterpillars of some moths, however, infest furs, which they gnaw with their powerful mandibles, and there are some adult members of the group, such as the Purple Emperor Moth, which are fond of carrion, drawing up its de- composing juices through the tubular proboscis formed by the elongation of the first maxillae. • FLIES (DlPTERA) (fig. 390) Many of the vast horde of Two-winged Flies which make up this order are either predaceous, or else subsist on animal matter. Most persons are under the impression that the common House - Fly (Musca domestica) is able to bite at certain seasons of the year, an erroneous idea partly due to the fact that a similar- looking insect exists which has piercing mouth-parts. This is the Stable-Fly (Stomoxys calcitrans] (compare fig. 392). The Fig. 391.— Tsetse-Fly (Glossinn morsitans] A, Adult fly (enlarged); B, Piercing mouth-parts, and c, Antenna (greatly enlarged). mouth-parts of the formidable Tsetse-Fly (Glossina morsitans) (fig. 391) of Tropical Africa are of similar kind. GAD-FLIES. — It is a common thing for the blood-sucking habit to be confined to the female insects, and a good example is fur- nished by the Gad-Flies, of which the Ox-Fly or Great Horse-Fly (Tabanus bovinus] is a terrible pest to horses and cattle. A much commoner British insect, belonging to the same family, is the familiar Clegg {Hcematopota pluvialis\ abundant in woods, and of particularly slow flight. Most of us have experienced the vicious stab this undesirable creature inflicts, and only an un- CARNIVOROUS INSECTS 121 HYPQPHXRYNX HLABIOM. usually benevolent person could resist the chance of immolating the aggressor, a particularly easy matter as it happens. Bot- Flies make up a family with reduced mouth-parts, and, though not blood- suckers, are more dangerous to horses and stock than Gad- Flies and the like, for they lay their eggs upon domestic animals, upon or inside which the larvae, when they hatch out, become parasitic. Details will be given when the question of parasitism is discussed. GNATS AND MIDGES. — Few animals cause more annoyance and discomfort than the Gnats, Mosquitoes, Sand-Midges, and, to a less extent, true Midges, which abound in all parts of the the world, and have been made notorious by the lurid descriptions of innumerable travellers. Mosquitoes and Gnats (Culicidce) are one and the same thing; a familiar British species is the Common Gnat (Culex pipiens\ which possesses typical piercing mouth -parts (fig. 392). The labrum is a long, pointed structure, with its grooved under side forming a •canal along which blood is conducted to the mouth. Both mandibles and first maxillae are lengthened out into pierc- ing bristles, by which a wound can be inflicted, and which are enclosed in a sort of sheath formed by a modification •of the labium. It should further be noted that a long, pointed tongue (hypo- pharynx), upon the end of which the •ducts of the salivary glands open, is •enclosed in this sheath, from the back part of which it grows out. Sand- Midges (Simuliid&\ poorly represented in Britain, are most abundant in the tropics, and though much smaller than Gnats, are even more noxious, their bite being particularly virulent. The name of " Sand-Fly" is commonly given to them. Midges (Chironomida} are minute insects, for the most part not adapted for blood-sucking, though to this there are exceptions, as in the •case of the common Black Midge (species of Ceratopogon), which is one of our summer pests in the country. In all these cases it is the female only that feasts on blood, and her mouth-parts are therefore adapted for piercing and sucking, conforming more or less closely to the type described for the Gnat. LABIAL PAITP. Fig. 392. — Mouth parts of a Female Gn ^ Culex pipens], greatly magnified 122 THE FOOD OF ANIMALS The Forest- Flies (Hippoboscidce) are curious Diptera, parasitic on the bodies of various warm-blooded animals, and presenting" us with a series of species showing the gradual degeneration and disappearance of the wings. This is interesting because it helps to throw light on those unpleasant and familiar creatures called Fleas, which are very likely to be looked upon as wingless Diptera, of which the remote ancestors possessed wings. The best-known species is the ubi- quitous Common Flea (Pulcx irritans) (fig. 393), but Mam- mals and Birds are infested by numerous other kinds, it being" a common error to suppose there Fig. 393-The Common Flea (Pulex irritant] is bu* °ne SOlt of these Crea- On the left are the piercing mouth-parts. On the right, tUrCS. The piercing and SUCk- larva (above) and pupa (below). Enlarged to various • 1 T rr • scales. ing mouth-parts differ in some respects from those of Gnats, &c. The long, pointed labrum is grooved on its under side, and is closely applied to the hard, piercing mandibles, while a sheath is formed by the two pairs of maxillae. The FRINGE-WINGED INSECTS (THYSANOPTERA) include minute forms which feed on plants, and therefore do not require notice here. BUGS (HEMIPTERA) In this, the last order of insects, are included a great variety of forms, such as bugs, aphides, true lice, &c., most of which are terrestrial, though a fair number are aquatic. The food may consist of the juices of animals or the sap of plants, and in either case the mouth - parts are adapted for piercing and sucking, though constructed on a somewhat different type from that described for the Diptera. Examination of one of these creatures (fig. 394) reveals the presence of a piercing beak, which consists of - 394- — Mouth-parts of a Tree-Bug (Cicada], enlarged; ant., antennae; «./., upper lip. CARNIVOROUS INSECTS 123 a tubular sheath, enclosing four piercing, and it may be barbed, lancets, representing the mandibles and first maxillae. Each of the former is doubly grooved on its inner side, so that, when opposed to its fellow, two channels are formed, along one of which the juices of the food are conducted to the mouth, while the other serves for the transmission of saliva. A gap left in the front of the tubular sheath is filled up by the pointed labrum. LAND-BUGS. — Most of the terrestrial Hemiptera are vegetarian in habit, but to this there are some notable exceptions. For ex- Fig. 395. — Larva of Reduvius personatus. Actual size shown by line. ample, a large British species, for which there is no common name, but which is known scientifically as Reduvius personatus (fig. 395), preys upon other insects, including, it is said, the objectionable bed-bug. The front legs are adapted for seizing prey — a peculiarity of which examples have been given among other insects — and the predaceous larva of this insect is remarkable for its disre- putable appearance, being covered with dust and rubbish in a remarkable way, an arrangement which probably shields it from observation. The evil-smelling Bed- Bug (Acanthia lectularia), of which the less said the better, is a wingless species. WATER-BUGS. — The habits of some of the aquatic bugs (fig. 396) are very interesting. Among them, the Pond - Skaters, slender insects which, so to speak, skate on the surface of the water, at once attract attention. The Needle -Bug (Limnobates stagnorum) Fig. 396.— A Pond-Skater (Gerri paludum), enlarged 124 THE FOOD OF ANIMALS is recognized by its extremely slender body and leisurely gait, while the Common Skaters (Gerris paludum) are somewhat broader, and very rapid in their movements, pouncing swiftly upon flies and other insects, which they seize with their fore- legs. The Water- Boatmen (Notonecta glauca and others) are comparatively broad aquatic bugs of predaceous habit, which swim on their backs, using the long hind-legs as sculls. More sluggish and of forbidding appearance are the Water -Scorpions and Long Water- Bugs. The common Water-Scorpion (Nepa cinerea) (fig. 385) is a sombre-looking flattened creature with large grasping front legs, the appearance of which suggests the popular name. There is also a curious bristle-like tail, which has to do with breathing, and will be described elsewhere. The Long Water- Bug (Ranatra linearis\ to use the words of Staveley (in British Insects), " resembles the Nepa in having a small head, two long tails, and extended prehensile fore-legs, but here all family likeness ends, for this most curious-looking creature is but a series of thickish lines (as ts name imports). A long linear body with two long thin tails, and four long thin legs, are all we can see except a pair of forceps \i.e. the fore-legs], which would be long and thin too if they were not so crooked. The creature looks cruel and hungry, but where it stows all the prey for which it is so greedy is a problem to be solved. A less aldermanic figure can scarcely be conceived. ..." A marine bug- (Halobates) (fig. 307) is Fig. 397--A Marine Bug (Halobates] . . & \ , • r i particularly interesting as being one of the very few insects which inhabit the open sea. It has been found skating on the surface, far out of sight of land. True Lice are wingless blood-sucking creatures, shown by the nature of their mouth-parts to be degraded forms of the Hemip- tera. The tips of their legs are hooked, so as to give a firm hold on the exterior of their host. CHAPTER X THE FOOD OF ANIMALS — CARNIVOROUS ARACHNIDA AND MYRIAPODA— PERIPATUS SPIDER-LIKE ANIMALS (ARACHNIDA) The second class of air-breathing Arthropods to be considered is that of the ARACHNIDA, including Scorpions, Whip- Scorpions, Spiders, False Spiders, False Scorpions, Harvestmen, Mites, and Ticks. SCORPIONS (SCORPIONID^:) (see vol. i, p. 385) These unpleasant creatures are found in nearly all the hotter parts of the globe, and all of them capture living prey of various nature. Scorpions are mostly nocturnal, and this may partly account for the fact that they perceive the presence of their quarry by touch rather than sight, and the large pincers are of im- portance in this respect, playing the part of tactile organs as well as of weapons. Many Scorpions find a refuge and lurking-place combined underneath stones or in convenient crannies, others make excavations in earth or sand for the same purposes. The large pincers {pedipalpi} are used for seizing prey, in which also the smaller nippers (ckelicera) in front of them may help, the narrow tail is then bent forward with great rapidity, and the sting in which it ends brought into use. Two poison-glands are lodged within the broad base of the sting, and open upon its tip. The mouth is extremely small, and the front part of the food-tube is specialized into a suction-pump by which the juices of the prey are extracted. WHIP-SCORPIONS (PEDIPALPI) (see vol. i, p. 389) The curious little WHIP-SCORPIONS (Pedipalpi\ widely distri- buted in the tropical and hot parts of both New and Old Worlds, are predaceous forms, unprovided with the poisoned sting of their larger namesakes. The hind end of the body may be possessed of 125 126 THE FOOD OF ANIMALS a thread-like appendage, looking like an attenuated representative of the Scorpion's tail, or, in some members of the group, there is nothing but a little knob to represent the tail. The tailed species have both small and large pincers, as in the ordinary Scorpions, but the latter are not so well developed. Those appendages of the tailless forms which are equivalent to the large pincers are of considerable size, but do not end in nippers, having instead a spiny end-joint, which can be bent back on the equally spiny joint by which it is borne to form an efficient grasping organ. The arrangement may be compared to that found in the fore- legs of the Praying Mantis (p. 117), and it is a common device in many groups of animals which require a simple holding- apparatus. It has already been pointed out that in Insects the slender feelers or antennae are of great use in giving the animal a means of exploring to the front, and that in Scorpions the large pincers are used for this purpose. The same end is attained in the Whip-Scorpions by diverting the front pair of legs from their usual locomotor function, while at the same time they are modi- fied into forwardly-directed organs of touch. The specialization has not gone far in the tailed members of this group, but in the tailless ones it is extreme. We have here an excellent example of the principle of " change of function ", of which instances have already been given in other connections, and the comparison of Insect, Scorpion, and Whip- Scorpion, just instituted, also illustrates another important biological principle, that of analogy, which lays it down as an axiom that organs performing equivalent functions are not necessarily equivalent as regards their origin and structure. SPIDERS (ARANEID^:) Spiders (Araneidce) are highly rapacious forms which con- stitute a large and exceedingly interesting order, distinguished from the other groups of Arachnida by many peculiarities. There are no large grasping organs as in the forms so far described, the appendages corresponding to them being short feelers with bases that are used as jaws. Poison-glands are present, however, but these, instead of being lodged in a posterior sting as in a scorpion, are contained within the first jaws (chelicerce), upon the tips of which they open. These jaws are not in the form of nippers, but present the arrangement just described for the seizing organs of whip-scorpions, the claw-like end-joint moving CARNIVOROUS ARACHNIDA AND MYRIAPODA 127 upon the toothed joint which carries it, as the blade of a penknife does upon its handle. Spider poison may be of an extremely virulent kind, as will be seen by the following extract from Semon {quoted from In the Australian Busti)\ — " More poisonous than all the other insects of Australia [the word ''insect" is here used in a popular way] ... is a little black spider writh a back of vivid red, Latrodectus scelio. This conspicuous spider seems to be everywhere. Though chiefly nocturnal in its habits, it also appears in daytime, imposing on you by a certain calm im- pudence. It takes no trouble whatever to escape or to hide, but, relying on its fatal poison, seems rather to warn you by its vivid colour than to elude your vision by a more modest mien. The bite of this spider is terribly painful, and in its wake we often find paralytic symptoms in the wounded member, its neighbouring organs, or even the entire body. It is said that grown-up people are sometimes killed by it, and surely this is the most poisonous spider in the world, and the most dangerous arthropod in existence." Undoubtedly, however the most inter- esting and characteristic feature about spiders is found in the spinning organs which they possess. These are in the form of silk-glands, which open by innumerable pores upon the surface of four little teat- like projections placed on the under side of the abdomen (fig. 398). WEB-SPINNERS. — The best-known kinds of spiders construct webs for snaring prey, the most perfect and regular of these con- trivances being the work of the numerous species included under the term " orb spinners ", of which the common Cross or Garden Spider (Epeira diademd) (see vol. i, p. 391) may be taken as a good type. Such a web consists of radiating strands which form a supporting basis, and of a sticky thread which winds round in a spiral way from centre to circumference, and holds fast any unfortunate insect that happens to fly against the snare, which is possessed of a considerable amount of elasticity, so as not to be readily broken. The spider lies in wait for prey in the neigh- bourhood of the web, concealed in some cranny or under a leaf, Fig. 398. —Spinnerets of Spider (greatly enlarged) 128 THE FOOD OF ANIMALS and a line running from its hiding-place to the snare gives notice by its vibrations of the capture of prey. Should a comparatively large insect be caught, the spider envelops it in a winding-sheet of silk, and either kills it at once, or, if already sated, leaves it for a future meal. The construction of such an elaborate snare as that of the Garden Spider requires no little ingenuity and care. To begin with, the apparently simple threads are in reality com- plex, being composed, like a rope, of a number of strands, in this case of extreme tenuity. The reason for sjach complexity is not far to seek. A thread composed of numerous strands is stronger than one of the same bulk would be if made in one piece only; and, further, the viscid material of which the web is composed obviously hardens more quickly when exposed to the air in ex- tremely slender threads than would otherwise be the case. The spinnerets of this particular spider are simply riddled like a sieve by the minute openings of silk-glands, there being, at a moderate computation, some 700 pores in all. The material secreted by the silk-glands is not all of the same kind, for some is destined to be worked up into the non- viscid radiating threads, while others supply the material for the sticky spiral one. Nor is the breadth of the component filaments the same in all cases. The feet of the spider are armed with several curved and toothed claws, and it is more especially those of the hind-legs which are used to work up the raw material into complex lines. The claws also enable the animal to easily climb about its web or travel along the connecting line running from its hiding-place. Staveley (in British Spiders) thus describes the way in which the spider constructs her regular web1: — " The process by which the net of the garden spider is con- structed is well worth observing. The first step is to extend a horizontal cord between two neighbouring points. This is done with the aid of the wind, the spider exposing the spinnerets to a current of air whilst emitting the fluid silk. A thread is thus, as it were, drawn from the spider by the power of the wind, and, coming into contact with some neighbouring object, adheres by its own natural stickiness. This is the commencement of the framework, which is completed by lines placed according to cir- cumstances, some by the spider dropping and swinging from point to point, attaching a thread wherever she touches, and others, as in the case of the first, by means of the wind. The framework 1 "She" has been substituted for "he" throughout the quotation. CARNIVOROUS ARACHNIDA AND MYRIAPODA 129 completed, the spider goes to the middle of the upper horizontal line, touches it with the spinnerets, so attaching the beginning of a thread to it, and drops perpendicularly on to the line forming the lowest side of the framework, where she fastens the second end of the thread. She then climbs up this till she reaches the middle (which is to be the middle of the web), and here she fixes the beginning of another thread. She now ascends the perpen- dicular thread, drawing out the new one as she goes, till she reaches the upper line, along which she walks to the point at which she sees fit to attach this radius of her web. She now returns to the centre, and repeats the process, each time walking up the last- formed radius as she draws a new one, till the whole area of the web is filled with radiating lines. " The next process is to connect the radii by a spiral line, so forming the meshes of the net. The spider places herself in the Fig. 399. — A House-Spider (Tegenaria} in its Web; arrangement of eyes shown at a. centre of the web, and attaching a thread there, turns round, drawing a line from the spinnerets, which she applies to ray after ray, fastening it with the aid of her hind -legs. She proceeds farther and farther from the centre until a spiral line has been described from thence to the circumference of the web, where she affixes another thread, and, reversing the operation, draws a second spiral line from the circumference to the centre." The Garden Spider and our other native orb-spinners are all of com- paratively small size, but there are some large tropical species VOL. II. 41 1 30 THE FOOD OF ANIMALS which construct snares of corresponding dimensions, and stated to be strong enough to capture small birds. A less-complex and differently-placed snare is constructed by the common Field Spider (Agalena labyrinthicd), of which the dense white webs are often to be observed on heaths and com- mons, stretched horizontally among such plants as furze. These are often extremely abundant, and seen when covered with dew in the early morning are exceedingly conspicuous. A dwelling for the spider in the form of a silken tub£ hangs down vertically from some part of the web, and at the mouth of this the occupant remains on the look-out for prey. The House-Spiders (species of Ttgenaria) (fig. 399) are members of the same family, and their dirty-looking snares, familiarly called " cobwebs ", are connected at one corner with the den of the spider, in this case a horizontally- placed tube open at both ends and slung from a support by means of a number of strong threads. HUNTERS. — The above will perhaps serve to give an idea of the way in which snare -spinning spiders secure their prey, and we may now turn our attention to some of the Hunting Spiders, which secure their victims either by craft or speed, or it may be by a combination of the two. Here are included the largest and most repulsive -looking members of the order, the Bird-catching Spiders of tropical and hot regions. A well-known South Ameri- can species (Mygale avicularia) (see fig. 384) has been described by Bates and other naturalists as of nocturnal habit, preying on all sorts of animals from birds downwards. As these creatures do not spin webs for the capture of prey, there is not the same need for well-developed claws, and we accordingly find that these are small, while tufts of hair are present, which are used as climbing pads, enabling the creature to scale smooth and steep surfaces. The Wolf- Spiders (fig. 400) include smaller species which run with great rapidity, and are thus enabled to overtake their prey. A number of small British spiders (species of Lycosa, &c.) belong to this group, but a much more notable species is the Tarantula (Lycosa tarantula] of South Europe, a larger kind, reputed to have a most virulent bite, only to be cured by extremely rapid dancing to appropriate music. This is, indeed, the origin of the dance known as the tarantella. One of our smaller native kinds of Wolf- Spider (Lycosa piratical) haunts the margins of ponds, and CARNIVOROUS ARACHNIDA AND MYRIAPODA 131 is able to run on the surface of the water in pursuit of prey, or even to dive, this being rendered possible by the entanglement of air -bubbles among the numerous hairs with which the body is covered. Another member of the same family, the Raft- Spider (Dolomedes fimbriatus], possesses the same powers as the pre- Fig. 400. — Hunting Spiders (Saliicus scenicus) ceding, but by constructing for itself a raft of leaves is able to make a more extended use of them. There are other families of spiders the members of which are thorough-going aquatic forms, a familiar British example being the Water-Spider (Argyroneta aquatica], of which more will be said in another connection. The last group to be here mentioned is that of the Jumping Spiders (fig. 400), which patiently stalk their prey and ultimately secure it by a final rapid jump. A very common little British form, the Harlequin Spider (Salticus scenicus], in which even the larger female is only about a quarter of an inch long, is distin- guished by conspicuous striped markings. FALSE SPIDERS (SOLPUGHLE) (see vol. i, p. 388) These arachnids are rapacious forms superficially resembling large spiders, and have a wide distribution through the warmer parts of both New and Old Worlds, ranging in the latter into the Mediterranean countries of Europe and the south-east of Russia. At first sight they seem to have ten pairs of legs, but the first pair of these apparent legs are in reality the appendages corresponding to the great claws of the Scorpions, serving in this case as feelers, a function which is also shared by the first pair of legs proper, somewhat as in Whip- Scorpions. The jaws are of large size, and the food chiefly consists of insects, though they also attack other arachnids, even Scorpions. Desert regions are especially affected by them. 1 32 THE FOOD OF ANIMALS FALSE SCORPIONS (PSEUDOSCORPIONID^E) (see vol. i, p. 389) These minute creatures owe their superficial resemblance to Scorpions chiefly to the fact that the first two pairs of appendages are constructed on the same plan. They do not, however, possess tails, and differ in many other ways from their namesakes. False Scorpions lurk under bark and in all sorts of crannies where they are likely to meet with their food, which consists of mites and small wingless insects. They are often to be found in old books, neglected plant collections, and the like. HARVESTMEN (PHALANGID^:) (see vol. i, p. 390) The members of this group, with which we are familiar in this country, look something like spiders with very long thin legs, but are in reality as unlike spiders in structure as false scorpions are unlike true ones. The first pair of jaws are strong nippers suited for seizing insects or other small creatures, while the second pair of appendages are feelers. MITES AND TICKS (ACARINA) Those members of this specialized group which live upon animal matter are parasitic in the most interesting cases, and consideration of them may be postponed till parasitism is dealt with. CENTIPEDES AND MILLIPEDES (MYRIAPODA) Centipedes, Millipedes, and their allies together constitute the third class of air-breathing Arthropoda, to which the name of Myriapoda has been applied on account of the large number of legs usually present. Millipedes are of vegetarian habit, and will be considered elsewhere. CENTIPEDES (SYNGNATHA or CHILOPODA) Centipedes are highly predaceous animals, feeding upon in- sects and other invertebrates. One of the commonest native species, the Thirty-foot (Lithobius forficatus) (see vol. i, p. 394), is an active, chestnut-coloured thirty-legged animal, common under stones and in garden earth. The head bears two groups of simple eyes and a pair of long feelers, which no doubt — the latter espe- cially— aid in the pursuit of prey. The mouth-parts are of biting CARNIVOROUS ARACHNIDA AND MYRIAPODA 133 nature, and in some respects conform to the description already given for insects of similar habit (p. 107). There are three pairs of jaws, of which the first are powerful mandibles, provided with strong tooth-like projections where they work against one another. Then follow first maxillae, each of which has two branches, and these are succeeded by a pair of second maxillae united together in the middle line, and looking very much like transformed legs, which no doubt they are. But a Centipede is better off in the jaw line than an Insect, for outside the second maxillae come still another pair of metamorphosed legs, closely united together in the middle, while each of them bears a jointed curved poison-claw, near the tip of which a poison-gland opens. The poisonous Centi- pedes of tropical countries agree essentially in structure with the species just described, but are very much larger, and possess more numerous legs. Their bite is dreaded by human beings, and is stated to be sometimes fatal. Nor must it be supposed that the food of such creatures is restricted to invertebrates, for they are known to attack small vertebrates of various kinds. Among the families of these creatures represented in Britain is one including the Earth Centipedes (Geophilidce) (see vol. i, p. 394), long slender forms which live under- ground and prey upon earth-worms. Their nar- row bodies are eminently adapted for burrowing through the soil, and also for twining round and round their wriggling prey, besides which it may be observed that eyes are altogether absent, clearly as a result of subterranean life. Preda- ceous Myriapods, however, may run to the oppo- site extreme, for in the Shield-bearing Centi- pedes (species of Scutigera) (fig. 401), so named from the presence of a single series of shield- shaped scales along the upper surface, we have forms which, instead of shunning the light, hunt their prey in open view. Possessed of very long antennae and well-developed compound eyes, they are able readily to detect the presence of suit- able victims, and their spider-like legs are swift in pursuit. Concerning these creatures, which by the bye are placed in a special order of Myriapods (SCHIZOTARSIA), Sinclair writes as follows (in The Cambridge Natural History): — "Some years ago Fig. 401. — Shield-bearing Centipede (Scutigera) 134 THE FOOD OF ANIMALS I was in Malta, and I used to go and watch them on the slopes outside Valetta, where they were to be found in great numbers. They used to come out from beneath great stones and run about rapidly on the ground or on the stones and rubbish with which the ground was covered, now and again making a dart at some small insect which tempted them, and seemingly not minding the blazing sun at all." PRIMITIVE TRACHEATES (PROTOTRACHEATA) • The last and lowest class, Prototracheata, of the air-breathing Arthropods, has been instituted for the reception of a single genus1 known by the name of Peripatus (see vol. i, pp. 399 and 400), of which species are distributed all round the world in tropical regions. Found in rotten wood and in crevices among stones, it looks not unlike a caterpillar with numerous pairs of clumsy-looking legs, each ending in a pair of claws. Though eyes are present, they probably do little more than enable the animal to avoid the light, and this slowly-moving creature seems to detect its prey, consisting of flies and other small animals, by means of its mobile feelers. Observations made on the New Zealand species show pretty clearly that sluggishness in move- ment is made up for by well-developed slime-glands, opening on a pair of short modified limbs (oral papillae) near the mouth. From these it is able rapidly to eject a sticky fluid to a distance of a foot, an arrangement which is probably as efficient as the sticky tongue of an ant-eater, a woodpecker, or a chameleon. Once secured, the prey is dealt with by a pair of jaws, working from side to side in the usual arthropod manner, and each pro- vided with a couple of sharp blades. It is a striking character of Arthropods generally that some of the limbs near the mouth should have assumed a chewing function, and here we have the arrangement in its simplest form, as but one pair of limbs is specialized into jaws. 1 This has recently been broken up into other genera, but the common usage is convenient in a popular work. CHAPTER XI THE FOOD OF ANIMALS— CARNIVOROUS CRUSTACEA AND KING-CRABS Air-breathing Arthropods having been now briefly reviewed, so far as carnivorous species are concerned, we now turn to aquatic Arthropods, breathing the air dissolved in water by means of more or less complicated gills > except in the case of some very small creatures which are able to perform this function by the general surface of the body. Amongst such forms by far the largest and most important class is that of the CRUSTACEA, including lobsters, crayfish, shrimps, prawrns, crabs, and a host of other forms. A very large number of these are carnivorous, some being adapted for the capture of living prey, while others feed on carrion. Indeed it may be said of the group that to a large extent they act as scavengers. The members of the KING- CRAB class (X^phos^lra) are also carnivorous. CRUSTACEANS (CRUSTACEA) It will be convenient first of all to consider the Higher Crustacea (Malacostraca), and afterwards to turn our attention to Lower Crustacea (Entomostraca). HIGHER CRUSTACEA (MALACOSTRACA)— STALK-EYED FORMS (THORACOSTRACA) The most familiar members of this subdivision belong to the DECAPODA, or Ten -legged Crustacea, of which the Lobster (Homarus vulgaris] has already been described as a type (vol. i, pp. 402-409). In such a form we can at once detect characters having relation to a predaceous habit, among which may be more particularly mentioned the huge pincers and the well- developed sense-organs, including more especially stalked com- 135 136 THE FOOD OF ANIMALS pound eyes and very long feelers (antennae), which are able to explore a considerable area in the neighbourhood of their owner. And, as might be expected in a scavenging animal, organs of smell are well developed, being here in the form of tufts of deli- cate flattened hairs attached to the small feelers (antennules), which are placed in front of the large ones. It is no doubt largely by the sense of smell that lobsters (and crabs) find their Fig. 402.— Gastric Mill of Crayfish (enlarged) A, Stomach in section. B, Parts of mill dissected out. oe, Gullet; vk, chewing region; hk, straining region; kl, fold between two parts of stomach; md, intestine; of, front bar of mill; so, side-bar; sz, bar carrying lateral tooth; mz, bar carrying middle tooth. way to the traps baited with offal that are set for them. These animals possess efficient means for dealing with the food when once this is secured, for there are no less than six pairs of jaws constituted by the specialization of limbs, and working from side to side in the usual arthropod manner. Nor is this all, for the Lobster, like many other crustaceans, is provided with a compli- cated chewing apparatus in the stomach, known as the gastric mill (see fig. 402), and consisting of a framework of hard parts which bear three tooth-like projections, one long ridged tooth on either side, and a forked median tooth borne on a downwardly-directed bar. By means of appropriate muscles attached to the framework the three teeth can be brought together so as to effectually crush anything that happens to be between them. The hinder part of the stomach is specialized into a straining apparatus, numerous stiff bristles projecting into its cavity and interlacing with one another so as to constitute a very efficient sieve. Such parts of the food as cannot be reduced to fine particles by the action of the jaws and gastric mill are ejected to the exterior through the mouth. The internal chewing arrangements remind one strongly CARNIVOROUS CRUSTACEA AND KING-CRABS 137 in function, though not in the details of structure, of the gizzards of birds, crocodiles, some insects, and certain molluscs. The Common Prawn (Palczmon serratus] is not unlike a minute lobster in structure, and naturally hunts down smaller prey. The Common Shrimp (Crangon vulgaris] is still smaller than the prawn, to which it has a general resemblance, differing, however, in many details of structure. There are no pincers, properly so-called, but the corresponding limbs are converted into grasping organs by the device already exemplified among various air-breathing Arthropods (pp. 114, 117); that is to say, the end-joint can be folded back upon the rest of the limb. Lobsters, Prawns, and Shrimps are all members of the Large- tailed Decapods, this region of the body being used like a fin, enabling the animal to dart rapidly backward through the water. Related forms are also to be found in fresh water, of which the most familiar is the Common Crayfish (Astacus fluviatilis), which is a notable scavenger, not limited in its diet, however, to animal matters, though it would seem to prefer food of that kind. It is said to make foraging expeditions in the neighbourhood of its native river, seizing worms, insects, snails, and any other small animals that happen to be available. Tropical rivers are the home of monstrous Prawns, such as the Jamaica Prawn (Palczmon Jamaicensis], found both in the West Indies and Central America, and remarkable for the enormous development of its pincers. Returning to marine Long-tailed Decapods, we find an in- teresting species in the spiny-looking Rock- Lobster (Palinurus vulgaris} (see vol. i, p. 412), in which the seizing limbs are con- structed on the same type as those of the Shrimp. The value of the tail as a swimming organ is here diminished by the fact that the tail -fin is quite soft, and this creature is commonly in the habit of "sitting" in wait for prey, with its soft fin pushed into a crevice among the rocks for protection. This case leads on naturally to the interesting forms known as HERMIT- or SOLDIER- CRABS, which are commonly included in the "Crabs" or Short- tailed Decapods, but are better considered as intermediate between these and the lobster-like forms. Taking such an example as the Common Hermit-Crab (Pagurus Bernhardus) (fig. 403), we shall find that it uses as a dwelling the shell of a gastropod mollusc, and is markedly asymmetrical in accordance with the shape of its 138 THE FOOD OF ANIMALS abode. In this instance the whole of the tail is soft, and the last pair of limbs, which in a lobster make up the sides of the tail- fin, Fig. 403. — Hermit Crabs (Pagurus Bernhardus}. One is taking possession of a new and larger house. are here modified into hooks for holding on to the inside of the shell. These animals are highly predaceous in habit, and also, as one of their common names indicates, extremely pugnacious. From Hermit-Crabs we pass to CRABS proper, constituting the Short- tailed Decapods (see vol. i, p. 411). The tail, in fact, is so short and small as to be useless as a swimming organ, and CARNIVOROUS CRUSTACEA AND KING-CRABS 139 is carried bent forwards against the under side of the thorax, which, together with the head region, to which it is closely fused, is broadened out into a shape varying according to the kind of crab. Swimming having been given up in ordinary cases, com- pensation is provided by the possession of running powers, which may be of no mean order. Regarding the food of Crabs and their part in the economy of nature, Frank Buckland (in Log-book of a Fisherman and Zoologist}, in describing a visit to the Brighton Aquarium, speaks as follows: — " Mr. Lawler kindly showed me the ' crabbery ' in the naturalists' room, where these unfortunate things are kept alive in hundreds (they cost one penny for four) for the octopus's dinner. He dropped in a bit of fish among them. In a moment the crabs near rushed towards it. The crabs at a distance, perceiving that 'something was up', began to run also, just as Londoners will run to a fire, an accident, or any other gratuitous amusement provided for them by circum- stances. In about half a minute there were at least twenty or thirty crabs fastened on to this one bit of fish — a living ball of crabs, in fact. The ball then began to roll. Some crabs fell off the ball on one side, while other crabs climbed up the ball on the other, and then the moving ball rolled away into the other end of the tank, the mass of crabs fighting, pushing, and pinching each other most gloriously." " I imagine, therefore, crabs must be very selfish creatures, and that they act on the principle of first come first served. But yet, do we not learn from this scene the great use of crabs? that is, to sweep up and tidy the bed of the ocean. If these active, hungry, and unpaid little scavengers were not in existence, all sorts of dead creatures, fish, shells, &c., would accumulate, and foul the water; but the crab's business and delight is to eat up all he can find. Therefore, I admire the little crabs for doing their duty, even though they do it unconsciously. Crabs are, in fact, the rats of the ocean, ready to eat up all the garbage they can find." So far as seizing organs, jaws, and gastric mill- are concerned, a crab essentially agrees with a lobster. The group is a very interesting one, and will frequently be mentioned in various con- nections. It may here be remarked that the very numerous species live under the most various conditions. Many are shallow- water forms, others live in deeper water, down to 2500 140 THE FOOD OF ANIMALS fathoms, i.e. over 2^ miles from the surface. Some, again, maintain themselves among floating sea-weed, as, for example, the little Gulf-weed Crab (Planes minutus), which is stated to have been pointed out by Columbus to his discontented mariners as a proof of the nearness of land, a good instance of the occa- sional usefulness of fallacious argument. It is also interesting to note that many marine forms have reacquired the power of swim- ming, though not in the old lobster -like fashion, for here pro- gression through the water is brought about by the flattening of the hindmost pair of legs into oars, an arrangement which reminds us of those found in some aquatic insects. This, how- ever, by no means exhausts the possibilities. A number of species, among which must be reckoned the common Shore- Crab (Carcinus mcenas) pick up a living between tide -marks, and there are all gradations between these and thorough-going land-crabs, most of which, however, feed more or less on vege- table matter, and therefore do not fall to be considered under the present section. The Swift Land-Crabs (Ocypodidce) (fig. 404) may be instanced as a carnivorous section of the last-named group, living on sandy shores. Stebbing (in A History of Crustacea] speaks of them as follows: — "As the name swift- Fis' (S^r^0*b of-foot implies, these Crustacea are espe- cially noted for their rapidity of move- ment. They are just the opposite of some of the strong-armed, thick-shelled, slow-moving Cancridcz, i.e. the group of which the common Edible Crab (Cancer pagurus] is a good type. On wind-swept stretches of sandy beach, and coloured like the sand, they sometimes seem rather to be borne on the wings of the wind than to run. Also, with their compressed lancet-like fingers they are extremely dexterous in digging into the sand. They burrow holes an ell deep, generally perpendicular, and from these they wander afar, when the tide is out, in search of food. Krauss observed in South Africa the species Ocypode ceratophthalmus (Pallas) and others, and he says that while they are busy hunt- ing, every now and then they look carefully round, raising their stalked eyes upright, and standing upon tiptoe. , At the slightest movement towards them they run with uncommon rapidity to the nearest hole, or, if the danger is too close, press themselves flat CARNIVOROUS CRUSTACEA AND KING-CRABS 141 on the sand till an attempt is made to seize them, and then off they dart. In running they carry their bodies high, doubling and dodging with such speed and cunning that it is a difficult matter to lay hold of them. When the tide comes up they are enclosed in their flooded burrows, and as soon as the waves retreat they are busily employed in clearing them, shovelling out the wet sand and heaping it at some little distance off. The American species, Ocypode arenaria (Catesby) is described by Professor S. I. Smith as having precisely similar habits. According to his observation, it lives largely upon the amphipods of the genus Talorchestia, known as 'beach-fleas', which inhabit the same localities. 'It will lie in wait ', he says, ' and suddenly spring upon them, very much as a cat catches mice. It also feeds upon dead fishes and other animals that are thrown on the shore by the waves." It may be finally noted that some Crabs are inhabitants of fresh water. MANTIS SHRIMPS (Stomatopoda). — In such a typical member of this group as the common Mantis Shrimp (Squilla mantis) (see vol. i, p. 411), found to some extent in British seas, the structure is clearly adapted to a predaceous life. The feelers and stalked eyes are well developed, and there are powerful seizing organs. These are not, however, the same pair of special- ized appendages as in a lobster, but correspond to the second pair of foot-jaws in that animal (vol. i, p. 406). But here, instead of three pairs of jaws and three pairs of foot-jaws, we find two extra pairs of the latter. The seizing organs do not end in pincers, but, as in several cases already described, have a blade- like end-joint which can be bent back on the rest of the limb. Mantis Shrimps excavate deep burrows in the zone below low- tide mark, and lie in wait for prey at the mouths of these. HIGHER CRUSTACEA — SESSILE-EYED FORMS (EDRIOPHTHALMATA or ARTHROSTRACA) The Sessile-eyed Crustacea (Edriophthalmata) derive their name from the fact that the eyes project directly from the head instead of being situated on stalks as in the forms so far con- sidered. The large majority of them are to be found in shallow water and on the shore, and are by no means restricted to salt water. Many of them play an important part in scavenging 142 THE FOOD OF ANIMALS the strand, not a few are parasitic, and some have become adapted to a terrestrial life. They include the Amphipocls, such as Sandhoppers and their allies, which are flattened from side to side, and the Isopods, which are flattened from above downwards. AMPHIPODS. — A very common example is the Sandhopper (Talitrus locusta) (see vol. i, p. 415), which haunts the shore between tide-marks, and in summer may be seen in countless thousands, springing several inches into 0 the air so as to be visible some way off, and looking almost like a quivering dust- cloud hanging over the surface of the sand. Like most members of its group, the Sandhopper lives chiefly, if not entirely, upon decomposing animal matter, and close examination with the aid of a powerful lens shows it to be possessed of strong biting mandibles, two pairs of maxillae (see Lobster, vol. i, p. 406), and a single pair of foot-jaws turned forwards so as to form a sort of lower lip. In northern latitudes Crustacea of related kind occur in such vast numbers as to be able to speedily do away with the stranded and putrefying carcasses of even such large Cetacea as whales and the like. An abundant and typical example of freshwater forms belonging to the same group is the Freshwater Shrimp (Gammarus locusta), and it may be observed in passing that the term " shrimp ", popularly applied in the case of this and many other forms, is somewhat misleading, for the true shrimps, with their stalked eyes and firm shield covering the head and thorax, belong to the totally distinct and higher group of Decapods (see vol. i, p. 410). Climbing about among sea-weed and zoophytes, in the tide- pools of the British and many other coasts, we can often find the weird-looking Skeleton-Shrimp (Caprella) (see vol. i, p. 415), typical of a subdivision of the Sandhopper group, and distinguished by an extraordinarily attenuated body. The abdomen is here reduced to a mere tubercle, and the thorax is correspondingly well-developed, its third pair of limbs bearing large climbing- claws, while at its hinder end are three pairs of legs. Jaws and foot-jaws are present as in a sandhopper, and behind the latter come the second thoracic limbs, specialized into seizing organs. Caprella may often be seen holding firmly to a zoophyte and waiting patiently for booty, the presence of which is made known by its two well-developed pairs of slender feelers. The CARNIVOROUS CRUSTACEA AND KING-CRABS curious " Whale-lice " found as parasites on the skins of Cetaceans are related to the Skeleton-Shrimps, though of very different proportions. ISOPODS. — Probably the best-known member of this group to ordinary observers is the Wood- Louse (Armadillidium vulgare), which rolls itself into a ball when disturbed; but as this and its terrestrial brethren are largely or mainly vegetarian in habit, they require no further mention here. Although by no means all of the marine forms are carnivorous, many of them are markedly so, and this is the case with the familiar " slaters" found lurking in rock -crevices between tide -marks. The Sea- Slater (Ligia oceanicd) (fig. 405), e.g., and the species of the shallow- water genus Idotea, are pre- daceous. Other examples are found in the species belonging to the genus Cirolana (see vol. i, p. 415), for which, as in so many other cases, only scien- tific names can be given. Speaking of one of these species (C. borealis] Stebbing says (in A History of Crus- tacea]'.— "It is a good swimmer, tena- cious of life, a savage devourer of fish, and not to be held in the human hand with impunity ". An allied American species preys upon an edible variety of crab. As may be imagined, well- developed biting jaws are present in such rapacious forms as those just mentioned. The marine Isopods also include a remarkable series of forms parasitic upon fishes and higher Crus- tacea. Some of these are so remarkably degenerate, as a result of their dependent mode of life, that they have lost all outward resemblance to their free-living relatives. The group has also freshwater species, of which one, the Water Wood- Louse (Asellus aquaticus], is often to be found among rotting vegetation, feeding upon both animal and vegetable substances. Fig. 405. — Sea-Slater (Ligia oceanica) i44 THE FOOD OF ANIMALS LOWER CRUSTACEA (ENTOMOSTRACA) The innumerable marine and freshwater Crustacea which come under this heading, and which are commonly of small or very small size, mostly feed upon minute organisms belonging indifferently to the plant or animal kingdoms, and therefore do- not fall under this section. Two of the included orders, however, embrace parasitic species, i.e. the COPEPODA, to which belong" " fish-lice ", and the CIRRIPEDIA or Barnacle order, in which are placed a number of strangely-shaped form's parasitic upon other Crustacea, or it may be upon animals belonging to other groups. These will receive mention when the question of Parasitism is discussed. KING-CRABS (XIPHOSURA) Having dealt with a few of the carnivorous forms belonging to the Crustacea, we come to the second class of gill-bearing Arthropods, i.e. the XIPHOSURA, including only the recent K ing- Crabs (see vol. i, p. 423), regarding the classificatory position of which there has been much discussion. They inhabit shallow water along the eastern coast of the United States and the south-east of Asia. The animal is of considerable size, and is covered on its upper side by firm protective armour, there being a strong horse-shoe-shaped shield (whence the popular name of 1 'horse -shoe crab") extending over head and thorax, and a large plate on the abdomen, to the hind end of which a long movable spine is attached. Upon the under side of the body the mouth is seen as a longitudinal slit surrounded by the rough and spiny bases of the six pairs of walking legs, all of which, except the last, are, in the female, provided with pincers, while in the male the first pair present the common arrangement of a seizing organ in which the end-joint can be turned back upon the rest of the limb. The rough bases of the limbs act as jaws, and this is probably to be looked upon as the simplest case of the modification of a limb for this purpose, since the original use as a leg is still retained, though in this particular instance chewing duties have also been added. The foot-jaws or maxilli- pedes, of which examples have been described among the Crustacea (see pp. 141 and 142), represent a still further stage in the development of jaws, where the locomotor function has been CARNIVOROUS CRUSTACEA AND KING-CRABS 145 given up, though the outward resemblance to a leg is still more or less apparent. King- Crabs are found where the sea-bottom is composed of mud, upon the surface of which they crawl, aided by the shoving action of the tail-spine, which is further used to right them if accidentally turned over. They also burrow into the mud, largely aided by the last pair of legs, the ends of which are peculiarly modified, and by the tail -spine, which is employed as a prop. The food consists of bivalve molluscs and marine worms, which are chewed between the bases of the legs. VOL. II. 42 CHAPTER XII THE FOOD OF ANIMALS— CARNIVOROUS ANNELIDS AND SIPHON-WORMS We have next to consider typical carnivorous members of the phyla ANNELIDA, which includes Bristle- Worms (Chaetopoda) and Leeches (Discophora), and Gephyrea (Siphon- Worms). BRISTLE -WORMS (CH^TOPODA) All the members of this group have their bodies clearly divided into a number of successive rings or segments, the number of these varying in different cases. A further character of importance is the possession of firm bristles or seta, imbedded in the sides of these segments, and sometimes very numerous and obvious, as in the marine Annelids (Polychaeta), or else, as in the terrestrial and freshwater Annelids (Oligochaeta), com- paratively few in number. We are here only concerned with the marine species, and for the present purpose it will suffice to draw a distinction between the free-living or errant forms which swim, creep, or it may be burrow, and sedentary forms which inhabit temporary or permanent tubes of various kinds. As one would naturally expect, it is among the former that are included the typically predaceous species. A common kind, the Sea - Centipede (Nereis), has already been described (vol. i, pp. 425-429), and it is obviously specialized in accordance with its carnivorous habits. A large field of activity is afforded by the possession of several modes of locomotion — swimming, by means of general undulations of the body; crawling and burrow- ing, with the aid of blunt bristle-carrying foot-stumps arranged along either side of the elongated trunk. As in predaceous animals generally there are abundant sense organs serving to detect prey. The foot-stumps are provided with tactile filaments (cirri), and the well-developed head carries a number of feelers 146 CARNIVOROUS ANNELIDS AND SIPHON-WORMS 147 of similar kind, as well as four eyes. The most extraordinary arrangement, however, is to be found in the seizing organs. Nothing is present at all comparable to the jaws or seizing limbs of many backboned animals, nor are there jointed limbs, which, as we have seen, are specialized for this purpose in both air-breathing and gill -bearing arthropods. But the food -tube begins with a muscular pharynx, which can be protruded so as to bring into play a pair of formidable horny jaws which project from its cavity. These having seized the prey, a reverse action takes place, bringing it within the body. Small Crustacea, mol- luscs, and sponges are the chief articles of diet. Comparable to the preceding in respect of its food, though with weakly -developed jaws, is the Sea-Mouse {Aphrodite aculeata) (fig. 406), which, however, is not a swimmer. Here the body is Fig. 406.— Sea-Mouse (Aphrodite aculeata} short and broad, and there are very numerous elongated bristles of beautifully iridescent appearance. The upper side is also covered with a sort of loose skin composed of innumerable small bristles matted together so as to enclose a space above the skin proper. LEECHES (DISCOPHORA) Most of these are entirely devoid of the bristles so charac- teristic of the preceding group, and there is a sucker at either end of the body, the mouth-opening being in the middle of the front one. Leeches are divided into those possessing jaws and those devoid of these structures. JAWED LEECHES. — The common Medicinal Leech (Hirudo medicinalis) (fig. 407) is a familiar freshwater type of the jaw- bearing kind. It moves about either by swimming in an undu- i48 THE FOOD OF ANIMALS lating manner or by creeping with the aid of its suckers, which are alternately attached to the surface upon which it progresses. Although devoid of the obvious feeler-like structures seen in such a worm as the sea-centipede, it is nevertheless richly pro- vided with organs of sense, there being transverse rows of tactile structures on the upper surface, and a number of peculiar eyes on the upper margin of the head. Attaching itself by the front sucker to the body of its victim, it cuts through the skin with Fig 407. — Structure of Medicinal Leech (Hirudo medicitialis] A, Dissection from side: m.s. mouth-sucker; p.s. hind sucker; j. a jaw; ph. pharynx; gl. gullet; i-n, pouches of crop; st. stomach; int. intestine; br. brain; n.r. nerve-ring; gl and £23, first and last ganglia of ventral cord. B, Mouth-sucker cut open from below, showing the three jaws, j.j.j. c, A jaw with its muscles and saw-like edge. D, Three-rayed bite, c and D much enlarged. three horny saw-edged jaws that project into the beginning of its digestive tube, the result being a three-rayed incision ad- mirably adapted for the exit of blood, which is pumped out by means of the muscular pharynx, that alternately dilates and contracts so as to constitute a sort of suction-pump. It should further be added that a number of small glands open into the pharynx and pour out a fluid which prevents the blood from clotting, as otherwise the sucking process would be hindered. The greater part of the food-tube consists of a very large crop, the sides of which are drawn out into pairs of pouches, an ar- rangement which permits a large quantity of blood to be stored up for leisurely digestion. It is therefore not surprising that a single full meal goes a long way. Blood-sucking Leeches are by no means limited to an aquatic life, and it is notorious that in tropical regions innumerable Land- Leeches harbour among damp vegetation, from which they sally forth to attack all sorts of warm-blooded animals, human beings not excepted. Many travellers have given vivid accounts of the operations of these unpleasant creatures. CARNIVOROUS ANNELIDS AND SIPHON-WORMS 149 It must not, however, be supposed that all the jawed Leeches are blood-suckers. Some of the terrestrial forms, for instance, live upon earth-worms, and many of the aquatic species also live upon small invertebrates. This is the case in the well-known and much-slandered Horse-Leech (Aulastomum gulo\ in which the jaws are not nearly so well developed as in the medicinal form. JAWLESS LEECHES make up for this deficiency by having the front part of the digestive tube in the form of a muscular tube which can be turned inside out and used for boring into prey, from which the juices are then extracted by the pumping action of the pharynx. Many of these forms are parasitic upon fishes, both marine and freshwater, while others, such as the freshwater genus Clepsine, live upon molluscs and other invertebrates. SIPHON-WORMS (GEPHYREA) Passing by the phyla including the much-specialized worms known as Moss-Polypes (POLYZOA), Lamp-Shells (BRACHIOPODA), and Wheel Animalcules (ROTIFERA), of which the average mem- bers can scarcely be called carnivorous, though they feed to a great extent upon animal matter, we come to the equally peculiar phylum of SIPHON- WORMS (Gephyrea). This is a very hetero- geneous assemblage of animals which, though they have lost external traces of segmentation, are usually regarded as being descended from ancestral forms of the nature of segmented worms. They are exclusively marine, and many of them, as the common Siphon- Worm (Sipunculus nudus), swallow sand for the purpose of extracting the nutritious organic matter which it contains. One of the included groups, however, which may perhaps be called the Bristly Siphon- Worms (Eckiurotdea), embraces at least some carnivorous species, though, as in so many other cases where the habits of animals are concerned, there has been a dearth of observation. None of the species are familiar except to the pro- fessional zoologist, and as one consequence of this it is necessary to use the scientific names in speaking about them. The bodies of these creatures are plump-looking and more or less cylindrical, while it is usual to find a certain number of bristles imbedded in the skin which have been compared to the similar but more numerous structures found in bristle -worms. A remarkable peculiarity is found in the presence of a narrow, very extensible THE FOOD OF ANIMALS proboscis, which projects from the front end of the body, and is used both as an organ of locomotion and for the purpose „ of detecting and securing prey. A groove runs along its under surface, and at the back end of this the mouth is situated. One example must suffice, the Green Bonellia (Bonellia viridis] (fig. 408), which has been the subject of very careful observation in the aquarium of the Zoolo- gical Station at Naples. The female has a fat green body some 2 inches long, and provided with a very long proboscis, forked at the end, and several inches in length even when in a quiescent state. The animal lurks in a rock-crevice or under a stone, and stretches out its proboscis in all directions in search of food, attaining in extreme extension the almost incredible length of nearly z feet, when it looks like Fig. 408.— Green Bonellia (Bonellia o / J viridis). Female on left, male (much a slender green thread. Should the forked enlarged) on right. , . end of this organ come into contact with the soft body of a small ascidian or other suitable prey, this is torn from its attachment and passed down the groove to the mouth. CHAPTER XIII THE FOOD OF ANIMALS— CARNIVOROUS UNSEGMENTED WORMS AND ECHINODERMS One of the phyla which include typical unsegmented worms next claims our attention, i.e. FLAT-WORMS (Platyhelmia). Of the three classes which it includes, two — the TAPE- WORMS (Cestoda) and FLUKES (Trematoda) — embrace forms which are greatly modified as the result of a parasitic habit. Typical instances have already been briefly described (vol. i, chap, x), and further details will be given in the section on Parasitism. The third class, that of the PLANARIAN WORMS (Turbellaria), comprises an immense number of predaceous forms, differing greatly in size, shape, and colour, and found in the sea, fresh water, and among damp land vegetation. The mouth is remarkably variable in position, but it is always on the under surface, though in different species it may be far forwards, in the middle, or a long way back. A thick-walled pharynx can be protruded and used to perforate the small animals serving as prey, from which the juices and succulent parts are then sucked. Innumerable micro- scopic rods are imbedded in the skin, from which they can be shot out, serving, it would appear, both as offensive and de- fensive structures, though their mode of action is not clear. ' Locomotion is effected by creeping, and aquatic forms can also swim by undulations of the flexible body. Organs of touch and eyes are present, especially at the front end of the body, and these are efficient enough to enable their possessors to detect their prey by night as well as in the day. Three groups are distinguished, which differ among other things in the shape of the digestive tube, i.e. marine species, Polyclades, in which the gut is much branched; marine, freshwater, and terrestrial forms, Triclades, with the digestive tube divided into three main branches ; marine, freshwater, and terrestrial forms, Rhabdocceles, in which the gut when well-developed is a simple tube. 151 THE FOOD OF ANIMALS POLYCLADES are distinguished by the extreme thinness of the oval or leaf-shaped body, which is often so closely pressed against a stone or other firm body as to be difficult to detach without tearing. The feeding habits have to some extent been observed in certain cases. The common British species Leptoplana tremellaris, for example, includes marine bristle-worms among its prey, enveloping them within its pharynx, which, when protruded, assumes the form of a frilled funnel (see vol. i, p. 446). It is suggested that the peculiar rodlets which can be ejected from the skin have previ- ously been used to overpower the victim, and that weakly specimens are most liable to attack. Once within the pharynx a powerful digestive juice is poured out upon the food, which in a softened condition is drawn back into the stomach for complete digestion. One form (Prostkiostomum), in which the mouth is placed far forwards, possesses a long tubular pharynx which can be rapidly protruded, proboscis fashion, and used to secure small worms. More numerous observations have been made upon the TRICLADES (fig. 409), which are highly carnivorous and, as in the pre- ceding group, use the pharynx as a weapon of offence, pushing it out from the centrally or, it may be, backwardly situated mouth. There is little doubt that in this group also the rodlets shot out from the skin exert a paralysing influence upon the prey. The freshwater specimens are known to attack worms, water-snails, and water-beetles, among other invertebrate forms. Land Planarians, which belong to this group, feed to a very large extent upon earth-worms, some of them being adapted to pursue these creatures underground, capturing them with the help of a sticky fluid poured out upon the under surface. Some, at least, among the RHABDOCCELE species are carnivorous in habit, and certain marine species are parasitic. Fig.409.— A Triclade Planarian (much enlarged),with pharynx protruded. The branched gut is seen within the body, j CARNIVOROUS UNSEGMENTED WORMS, &c. 153 HEDGEHOG-SKINNED ANIMALS (ECHINODERMATA) The large and characteristic phylum of the Hedgehog-skinned Animals, or ECHINODERMATA, to which Sea-Lilies, Feather-Stars, Star-Fish, Brittle-Stars, and Sea-Urchins belong, does not include a majority of carnivorous species. The most characteristic forms in this respect are undoubtedly the Star- Fishes, of which the Com- mon Star-Fish or Five-Finger (Uraster rubens) may be taken as type. Crawling slowly along by means of the innumerable tube- feet, which protrude from five grooves on the under side of the body, the central mouth (from the neighbourhood of which these grooves radiate) is from time to time brought into the neigh- bourhood of some desirable bit of food in the form of a mollusc, crustacean, or other animal. Then follows a process which re- minds one of what takes place in a planarian worm, for while the clinging body of the Star- Fish holds down the booty, a large pouch-like stomach is protruded, which folds itself round the desired object and, having enveloped it, is drawn back by special muscles into the interior of its owner, where the process of digestion is carried on. Star- Fishes appear to be among those animals which do scavenging work, and Mr. Saville Kent is inclined to think that this is part of their business in oyster- beds, where they are usually believed to play havoc among the inhabitants. Regarding them this author (in The Great Barrier Reef of Australia) writes as follows: — "Star-Fishes of all de- scriptions, but more especially the ordinary five-rayed varieties, Asteriadae, are universally held up for condemnation as repre- senting the most insatiable foes of the oyster tribe. Whether this wholesale condemnation is a just one there are some reasons for doubting. In many instances it has been observed that the star-fishes were merely acting as scavengers and preying on dead or dying bivalves. The direct experiment was carried out by the author some years since, in one of the large English public aquaria, of keeping oysters and star-fish, including the accredited most aggressive species, Asterias (Uraster] rubens, in the same tank. The pre-supposed aggressors and their help- less victims were thus maintained side by side in perfect health for many months without a single instance occurring of molestation of the oysters on the part of the star-fish. The Echinoderms, how- ever, demonstrated their possession of normal healthy appetites i54 THE FOOD OF ANIMALS by feeding freely on portions of cut-up fish occasionally placed in the tanks." It has been proved that Star- Fishes are largely guided in their hunt for food by the sense of smell, and this is a common characteristic of many scavenging animals. On this subject Romanes (in Jelly -Fish, Star-Fish, and Sea- Urchins] describes his observations in these words: — "The presence of a sense of smell in star-fish was proved by keeping some of these animals for several days in a tank without food and then presenting them with small pieces of shell-fish. The star-fish immediately perceived the proximity of food, as shown by their immediately crawling towards it. Moreover, if a small piece of the food were held in a pair of forceps and gently withdrawn as the star-fish approached it, the animal could be led about the floor of the tank in any direction, just as a hungry dog could be led about by continually withdrawing from his nose a piece of meat as he continually follows it up." CHAPTER XIV THE FOOD OF ANIMALS— CCELENTERATES, SPONGES, AND PROTOZOA Passing downwards in the animal scale we come to the in- numerable marine forms, often of extreme beauty, which are grouped together in the phylum CGELENTERA, and include Zoophytes, Jelly- Fish, Sea- Anemones, Corals, and Comb- Jellies. Three classes are recognized: — (i) CTENOPHORA, Comb- Jellies; (2) ANTHOZOA, Sea- Anemones and most Corals; (3) HYDROZOA, Zoophytes, Jelly- Fish, and some Corals. The creatures em- braced by these three classes are all actively predaceous, and the methods of capturing prey will be described with reference to a few typical forms. COMB-JELLIES (CTENOPHORA) A common British Comb- Jelly, Cydippe (see vol. i, p. 483), has a translucent body shaped like a small melon, which is rowed through the water by eight longitudinal rows of little paddles, which suggest by their appearance the teeth of a comb, hence the word Ctenophora (Gk. cteis, a comb; ph£ro, I carry) and its popular equivalent. The digestive organs are represented by a complicated system of canals traversing the jelly-like body, and opening by a mouth at the end which is kept hindermost during swimming. Two long branched tentacles protrude from pouches in the side of the body, and can either be extended to a rela- tively great extent or else withdrawn altogether from the surface. These tentacles are veritable fishing-lines which capture the food, consisting largely of minute crustaceans, by means of innumerable minute sticky knobs with which they are beset. Should the victims attempt to escape they are " played " by the straighten- ing out of the elastic spiral stalks with which these knobs are provided, and when exhausted are conveyed to the mouth. 155 156 THE FOOD OF ANIMALS Fig. 410. — Beroe In another common type, Beroe (fig. 410), there are no fishing- lines, but the body is shaped like an elongated pointed cap, the wide opening of which is to be regarded as a mouth. Some of the species are of large size, and swimming is largely effected by the alternate contraction and relaxation of the walls of the body. The prey consists to a great extent of other sorts of comb- jellies, and there is small chance of escape for any of these which are so unfortunate as to be engulfed within the capacious central cavity of this vora- cious cap, provided as it is with hooks. SEA-ANEMONES AND TYPICAL CORALS (ANTHOZOA) A brief description of a Sea-Anemone has elsewhere been given as illustrative of the struc- ture of this class (see vol. i, p. 473). We are here concerned with the capture of prey, and at first sight a fixed animal, which resembles when extended a brilliantly -coloured flower, does not appear capable of playing havoc with its neighbours — certainly not with such forms as fishes and crustaceans (fig. 411). Appearances, however, are unusually deceptive in this case, for the innocent-looking "petals" are aggressive tentacles, armed with innumerable ''nettling organs", and they surround a large mouth which can be easily stretched so as to admit prey of compara- tively large size. The modus oper- andi is graphically described by Fred Smith (in The Boyhood of a Naturalist). The boy has brought home from the sea -side his first collection of marine animals, in- cluding a large contracted ane- mone, of which its donor, a friendly fisherman, had said: "If he blows, he'll astonish you; and if he ain't hurt he will, purviding you put him into some of your fresh sea -water when you get Fig. 411. — A Sea-Anemone. Notice mouth surrounded by tentacles. CGELENTERATES, SPONGES, AND PROTOZOA 157 home". Then follows the sequel. "When put into the fresh water the diseased -looking potato had fallen to the bottom of the bottle, and lay there apparently dead as any potato ever was. And now — can words describe it? — it was three times its former girth, and rose up like some green-and-red- striped cactus plant, two-thirds the height of the bottle, where it burst into a myriad delicate grey-green petals, which merged at their base into as delicate a pink, and they radiated at the top exactly like the florets of a chrysanthemum, and in such luxuriance that the bottle was not nearly wide enough for their free expansion." Two brothers of unscientific tendencies are then introduced to the marvel, " when someone, out of the purest mischief, dropped one of my live shrimps right on to the top of it, and then a curious thing happened. Instead of the anemone closing up, it seemed to expand itself more fully; the shrimp, after only one or two attempts to dart about, was distinctly taken hold of, so to speak, by the petals or ten- tacles of the anemone, and then it gave up in the most unexpected manner all attempts even to struggle. When I say the ' petals ' held the shrimp, they only seemed to touch it, and yet to securely hold it. In fact the shrimp seemed to become paralysed and utterly helpless, and then it was in a mysterious manner handed along over the top of the tentacles, they all bending slightly in sympathy towards the poor shrimp; and in, say, half a minute, it disappeared, without a struggle, into the mouth in the very centre of the creature, which, now that it behaved like an animal, looked like nothing else than an elaborately-decorated stomach." The present writer remembers on one occasion put- ting some healthy whiting into a small aquarium containing some expanded anemones. The fish came into contact with the tentacles of these, and with startling result, for next moment they were floating in a moribund condition, back downwards at the surface of the water. It may be worth while to ex- amine rather more closely the nature and action of the " net- tling organs ", of which the action has just been described, and which are potent enough in many cases to pierce the human skin with painful results. Varying largely in the details of their structure, these organs are present in most of the animals included in the Anthozoa and Hydrozoa. The "nettling organs", "stinging-cells", or "thread-cells", as they are variously called, THE FOOD OF ANIMALS are microscopic structures imbedded in the body -wall, and particularly abundant on the tentacles, where they are often aggregated into " batteries ", giving rise to a roughened ap- pearance as seen under strong magnification. Each of them (fig. 412) is a highly-modified cell, and before use looks like a little vesicle or bladder within which a thread is coiled up. The bladder contains a poi- sonous fluid, and its elastic wall is covered by a thin layer of living matter or protoplasm, from which a stiff " trigger -hair " projects to the exterior. The layer of living substance covering the vesicle has been described as in connection with a nerve-fibre, and this again with a nerve-cell. The coiled thread is hollow, and can be shot out to the exterior by pressure of the fluid in the vesicle, the motive power being supplied by the living layer, which is capable of contracting so as to exert a squeezing action. During the process the thread is necessarily turned inside out (see fig. 412), and the first part to emerge is provided externally with a varying number of back- wardly - directed spines. The apparatus is under nervous control, and the animal undoubtedly exerts discriminative power, for the contact of, say, a sand- grain with the trigger-hair leads to no result. But if suitable prey, such as a shrimp, is the disturbing influence, the stinging-cell " explodes", i.e. the thread is rapidly protruded to the exterior, its spiny base inflicting a wound, and holding fast like a barbed arrow. Part or all of the rest of the thread is then ejected into the wound, and the poisonous fluid is able to exert its full effect. Should the victim struggle, Fig.4i2. -Thread- and it often does, other tentacles are brought up to the attack, and it is eventually overcome by the action of a sufficient number of stinging-cells. These differ from the adhesive knobs of a Comb- Jelly in the fact that they can be only used once, and after explosion are cast off, being constantly replaced by the growth of others. CORALS. — Anemones are devoid of any hard parts, but their relatives the Corals (fig. 413) are well-endowed in this respect. The simplest Corals are solitary, and each of them has its base larged). The one on the right is ex- ploded AUSTRALIAN SEA-ANEMONES AND CORALS (After Saville Kent.) Drawn to various scales Among marine animals few possess such striking hues as Sea- Anemones and Corals. It would appear to be, at least in many cases, " warning coloration ", by which these apparently defence- less creatures give notice of unpleasant qualities. They are, in fact, provided with innumerable microscopic stinging capsules, which make them inedible to most carnivorous fishes, &c. ANEMONES 1. Heterodactyla Hemprichii. 2. Heterodactyla hypnoides. 3. Giant Anemone (Discosoma Haddoni). (Over 12 inches in diameter.) 4. Physobrachia Douglasi. (Only tentacles are seen.) CORALS 5. Cceloria. 6. Stylopora palmata- AUSTRALIAN SEA-ANEMONES AND CORALS i. Heterodactyla Hemprichii. 2. Heterodactyla hypnoides. 3. Giant Anemone. 4. Physobrachia (tentacles). 5. Caeloria (coral,*. 6. Stylopora (coral). CCELENTERATES, SPONGES, AND PROTOZOA Fig. 413. — A Branching Coral supported by a flat or cup-shaped skeleton. The remaining Corals are colonies, formed by the budding of one primary individual. Each member of the colony is essentially like an anemone in structure, and the various individuals are connected together by a common body, just as the leaves of a plant are continuous with the branching stem. All sorts of shapes are assumed in different species. It may not be altogether superfluous to quote here the remarks of Saville Kent (in The Great Barrier Reef of Australia) about the once popular and even yet not altogether defunct fallacy which ascribes the formation of coral to an intelligent and industrious " insect ". " Notwithstanding the wide diffu- sion of knowledge, which includes a smattering of many * 'ologies ', it is astonishing to find how tenacious an influence ancient tradition concerning coral organization still exerts on the public mind. The poetic fallacy of coral-reefs being built up by an association of 4 insects ' between which there subsists a relationship analogous to that which obtains between the * busy bee and its waxen cell ' is frequently enunciated from the pulpit, and in the pages of the daily newspapers. . . . Doubtless there is a large section of the public whose zoological lore will ever remain restricted to the narrow limits of that of Punch's railway porter, who, puzzled as to the classification of the old lady's tortoise, declared that, being ' neither a dawg nor a bird, it must needs be a hinsec '. There is also a very large multitude to whom the term * insect ' includes everything not distinctly referable to the category of * flesh, fowl, or good red herring '. . . . The coral animal ... is, individually, a simple polyp, comparable in every essential detail with the ordinary simply - organized sea - anemone familiar to every sea-side or aquarium visitor, with the exception that it possesses the power of secreting a dense, calcareous, skeleton out of the lime held abundantly in suspension in probably every sea. i6o THE FOOD OF ANIMALS ZOOPHYTES, JELLY-FISH, AND MILLEPORE CORALS (HYDROZOA) A simple example of this class is the common Freshwater Polyp (Hydra) (see vol. i, p. 465), which is practically a living stomach of cylindrical shape, attached by one end, which is closed, while in the centre of the other is a dilatable rounded mouth, placed at the apex of a conical pro- jection. Around the base of this projection are arranged a num- ber of hollow tentacles, richly provided with thread-cells, and cap- able of being stretched out for a considerable distance in search of prey. The branching sea- weed -like struc- tures known as Hy- droid Zoophytes (fig. 414) are in reality colonies of hydra-like individuals which capture prey by means of their tentacles. In many cases such colonies give rise to Jelly- Fish or Medusae (see vol. i, p. 479) comparable in shape to an umbrella, the mouth being situated at the end of the handle. Other sorts of jelly- fish arise by the transverse division of certain simple zoophytes, and others again have no fixed stage in the life-history. In all cases nettling-organs are present in great abundance, especially upon slender tentacles with which the umbrella is fringed, and upon lobes and filaments placed in the neighbourhood of the mouth. MILLEPORE CORALS. — A very interesting group of Hydrozoa is that containing certain corals, of which the Millepore Coral (Millepora) (fig. 415) may be taken as an example. This is a colony, of which the shape depends upon the species, and it is Fig. 414.— A Hydroid Zoophyte (Tubnlaria) CCELENTERATES, SPONGES, AND PROTOZOA 161 interesting as exhibiting division of physiological labour between the members of the colony, a very common phenomenon in the animal kingdom. As regards nutrition we can distinguish be- tween individuals which serve as stomachs, and slender mouthless indivi- duals richly provided with nettling-organs and con- stantly fishing for prey. Each of the larger feed- ing individuals is sur- rounded by a circle of the fishers, which provide it with food. As all the members of the colony are connected together by the common flesh, anything which is caught and digested benefits all tj-.fi nfMCrhhrnirincr nnlvnc; Fi&- 415-— Group of individuals from a Millepore Coral (Millepora) ClgllUUUl lllg puiy JJS (enlarged). A feeding individual surrounded by five fishers more or less. COMPOUND JELLY- FISH. --- Division of labour, however, is carried to a far greater extent in another group, that of the Compound Jelly- Fish (Siphonophora], including a large number of translucent free-swimming forms such as Diphyes, Physophora (fig. 416), and Velella. Each of these is in effect a floating colony produced probably by the budding of an originally single jelly-fish, the shape of the colony being determined by the method of budding, whether from the under side of the original umbrella or from the surface of the much-elongated handle, which is converted in many cases into a long trailing stalk. The members of the colony, or it may even be the organs of certain members, are specialized in all sorts of ways to perform different functions. One may be a gas-containing float, others may be swimming -bells, and so on, but those which are of special interest in the present connection are trumpet -like feeding-individuals which receive and digest food for the common good of the colony, and slender often branching fishing-lines which trail in the water and capture prey. A good example is the Portuguese Man-of-war (Physalia), which VOL. II. 43 162 THE FOOD OF ANIMALS consists of a huge float to the under side of which other, sorts of individuals are attached, including very long fishing-lines, of Fig. 416.— A Compound Jelly-Fish (Physophora hydrostatica] At the top a small float. Below this a stalk bearing swimming-bells. Next follow protective covering-pieces (darkly shaded), from between which one of the trumpet-shaped feeding individuals is seen projecting. Branched fishing-lines trail below. which the stinging organs are so numerous and powerful that they may seriously injure persons who are incautious enough to handle them. CCELENTERATES, SPONGES, AND PROTOZOA 163 SPONGES AND ANIMALCULES (PORIFERA AND PROTOZOA) Comparatively little is known about the feeding habits of the animals belonging to the two lowest phyla of the animal king- dom— PORIFERA (Sponges) and PROTOZOA (Animalcules), — and as, apart from certain parasitic forms which will be dealt with else- where, the food is for the most part of mixed character, we may now proceed to consider a few types, from Mammalia down- wards, in which there are interesting adaptations to a diet entirely or mainly of vegetable nature. CHAPTER XV THE FOOD OF ANIMALS — PLANT-EATING MAMMALS So much space has been devoted to the consideration of carnivorous forms that the limits of this work will only permit of comparatively brief notice of animals which feed on vegetable matter; but the importance of this kind of food must not be under-estimated, since all animals are dependent upon it either directly or indirectly. Indeed, it may be said with truth that green plants (as opposed to fungi, &c.) are the primary source of living matter, since they alone are able to build it up from simple chemical compounds, including the carbonic acid gas of the air and the inorganic salts dissolved in the water of the soil. Beginning with the phylum VERTEBRATA we will consider in succession the several classes, starting with the Mammalia. MAMMALS PRIMATES It is but few of the highest order of Mammals, the PRIMATES (Man and Monkeys), that are adapted for a purely vegetable diet. Man himself, whatever vegetarians may say to the con- trary, is specially suited to a mixed diet, as will appear in another section. The internal arrangements of mammals feeding entirely on plants have to be constructed on a special type, in order to deal successfully with the large bulk of food required, for pro- longed digestion is necessitated, and also a large extent of absorbing surface. Among those monkeys which are mainly or entirely vegetable - feeders may be mentioned the Entellus Monkey (Semnopithecus entellus] (see vol. i, p. 72), held sacred among the Hindus, to whom it is known as the Hunuman. The canine teeth do not here attain the size and prominence that is so characteristic of many carnivorous mammals, nor are there 164 PLANT-EATING MAMMALS 165 sharply-pointed cheek-teeth as in insect-eating forms; but these negative features are not so conclusive as the positive indication of plant-eating habit afforded by the stomach, which, instead of being a simple sac as in man and most monkeys, is complex, consisting of three separate divisions. Vegetarian mammals, notably the ruminating forms, commonly possess a complex arrangement of the sort. Reasoning from analogy, Owen, after studying the anatomy of monkeys of this group, put them down as leaf -eaters at a time when the nature of their food was a matter of conjecture. Subsequent observation proved the correctness of this surmise, as Entellus Monkeys and their kind feed largely on leaves and juicy shoots. HOOFED MAMMALS (UNGULATA) The majority of the animals included in the large and im- portant order of UNGULATA are characteristically vegetable-feeders, though the omnivorous pigs and their allies form an important exception to this. It may be remembered that there are two sub-orders of Ungulates (see vol. i, p. 104) — (i) the odd-toed forms or Perissodactyles, including Tapirs, Rhinoceroses, and Horses; and (2) the even-toed species or Artiodactyles, including the non-ruminating groups of Swine and Hippopotami, and the ruminating animals embraced under the headings of Deer, Antelopes, Cattle, and Giraffes. It will suffice for the present purpose to devote most of our space to considering in detail the food and feeding of the Horse and Ox, highly specialized repre- sentatives of the two sub-orders. The points specially deserving consideration will be the means employed in securing food (prehension), and afterwards reducing it to a fit state for absorp- tion into the blood and lymph. The Horse (Equus cabalhis], like most grazing animals, spends a large part of its time with the head bent down to the ground, and if the raising of it, which is constantly necessary, were brought about by muscular action solely, a wasteful amount of force would be expended. But in such cases the greater part of the work is done by the elasticity of a strong neck-ligament, which runs from the back of the skull to the long spines of the chest vertebrae, and sends branches forwards to be attached to the joints of the neck. Herbage is gathered into the mouth by the agency of the lips, which are extremely sensitive and flexible. Regarding them, 166 THE FOOD OF ANIMALS Flower remarks (in The Horse: A Study in Natural History) :— " Anyone who has seen a horse take a small piece of sugar from a child's hand will appreciate the delicacy and efficiency of these organs as instruments of prehension". Perissodactyles generally are distinguished by lips of this kind, and in the Tapirs (see vol. i, p. 105) the snout is produced into a short mobile proboscis, partly formed by extension of the upper lip. The nature of the food is commonly indicated by the characters of the teeth, and Fig. 417. — Complicated Grinding-teeth of Horse (Equus caballus] this is strikingly exemplified in the Horse (fig. 417). Incisors for cutting through grass and the like are well developed in both jaws, but canines, not being required, as in the Carnivora, for seizing prey, are not well developed, and in the Mare are either entirely absent or represented by mere vestiges. Adaptation to vegetable food comes out strongly in the complex cheek-teeth, which possess long grinding crowns, marked by a complicated series of folds and ridges. And it is particularly noticeable that the projecting part or crown of a horse's tooth not only con- sists of hard dentine and very hard enamel, as in a human molar, but also of a great deal of a bony substance, cement, which fills up the " valleys" in the crown, instead of, as in simpler cases, being confined to a thin layer on the parts imbedded in the gum. In this way unequal wear is provided for by which the top of the crown is always kept rough, instead of wearing down to a smooth ineffective surface, as would otherwise be the case. The teeth of a tapir or rhinoceros are much less complicated than this, but a study of the genealogy of the Horse, as established by fossils, shows that in the course of ages comparatively short and simple cheek-teeth, not unlike those of tapirs, have gradually attained the specialized condition which is now so characteristic. Herbivorous animals, in order to obtain the nutriment which they require, have to take in a comparatively large bulk of food, PLANT-EATING MAMMALS 167 and their digestive organs are of corresponding size. One result of this is that the abdomen is large as compared with the thorax, the proportions being reversed in carnivorous forms, which have to deal with a comparatively small bulk of highly nutritious matter. The Horse is not an extreme case, for it feeds little and often, as compared with some other forms living on the same kind of food, but the general proportions of its body are strikingly different from those of a dog or cat, for the reason indicated among others. Once swallowed, a large digestive and absorptive sur- face is necessary to deal successfully with vegetable food, and to meet this requirement the food -tube of herbivores is both long and more or less possessed of swollen regions. We have seen, for example, that the stomach of the leaf-eating Entellus Monkey is large and divided into several compartments. As to length, the Horse affords a good illustration of the principle, for its intestines are from ten to twelve times the length of the body, while in a cat they are only four or five times as long. The stomach of a horse is not specially capacious and its shape is simple, but an interesting feature may be noted in the character of its lining, which in the left-hand part is hard and tough, while in the right-hand portion it is soft and glandular, secreting the important digestive fluid known as gastric juice. In other words, the right-half region is that which is especially concerned with chemical digestion. The digestive tube of the Horse does, how- ever, possess an exceedingly large dilated region in the blind pouch or cacum, which grows out from the beginning of the large intestine. It is probable that this has to do with the digestion of plant -membranes, which are composed of cellulose ', a substance which, though allied to starch and sugar in com- position, is notoriously difficult to digest, as human beings often find to their cost if they swallow the skins of grapes, gooseberries, and other fruits. Turning now to the Ox (Bos taurus), we find that, as in the horse, there is a strongly -developed elastic neck -ligament (the pax-wax of butchers), having the use already mentioned. The mouth is placed on a large blunt muzzle, and the lips are com- paratively immobile, their food being grasped in this case by the large rough tongue, which is extremely flexible, and can seize tufts of herbage, drawing them into the mouth. The teeth present features which are characteristic of most common rumin- 168 THE FOOD OF ANIMALS ants. Cutting incisors are present in the lower jaw, and also canines which resemble them in shape, being quite unlike the lower tusks of Carnivores, to which they correspond. Front teeth, however, are entirely absent in the upper jaw, their place being taken by a hard elastic pad, against which the teeth below bite. The point is illustrated by the old story of the knavish dealer who sold some old ewes to a greenhorn as particularly fine lambs, pointing out as proof that the upper front teeth had not been cut. The cheek-teeth are complex grinders, something like those of the horse, but not nearly so specialized. Enormous salivary glands are present, in correlation with the starchy matter of which the food largely consists, and which is converted into sugar by the action of saliva and pancreatic juice. The internal digestive organs are exceedingly bulky, the intestines being from Fig. 418. — Stomach of Sheep (Ovis arie~ Shown cut open on right. The lower end of gullet is seen above and beginning of intestine to left. pa. Paunch; ret. honey-comb stomach; ps. manyplies; r.st. rennet stomach. twenty to twenty-two times the length of the body, much longer than in the Horse, though not equalling the Sheep and Goat, where they attain as much as from twenty-eight to thirty times that rela- tive length. The most remarkable peculiarity of the Ox and other ruminants, however, is found in the enormous and complex stomach (fig. 418), related to the habit of rumination, or, as it is popularly termed, " chewing the cud ", which enables these animals to take in a large bulk of food very rapidly, and afterwards to masticate it at leisure. To this stomach there are no less than four com- partments, as follows: — (i) An enormous paunch (rumen) on the left-hand side, and having about nine-tenths the entire capacity of the stomach; it communicates by a wide aperture with (2) the honey-comb stomach (reticulum), so called because its lining is raised into a net-work of prominent ridges presenting some re- PLANT-EATING MAMMALS 169 semblance to a honey-comb; this compartment opens into the (3) manyplies (psalter or omasum), the name of which suggests the fact that its lining is raised into numerous folds, projecting almost like the leaves of a book (such as a psalter or psalm-book, for instance) into its cavity; the manyplies is continued into the last compartment, (4) the rennet stomach (reed, abomasum), from which the small intestine leads out. The first three chambers are lined by a thick hard membrane, reminding us of the left-hand part of the horse's stomach, and it is not unlikely that in both cases we have to do with a dilated part of the gullet, comparable to the crop of a bird, and not really a part of the stomach at all. The fourth or last compartment is the true chemical stomach, and is lined by a soft membrane secreting the gastric juice. This con- tains pepsin, and also a milk-curdling substance (rennin), which is the source of the rennet used in cheese-making. The food is cropped rapidly, and swallowed without being properly chewed, passing into the paunch. Here it gets into a sodden condition, and later on, when the animal begins to " chew the cud ", is made up into boluses in the honey-comb stomach, and returned to the mouth for thorough mastication. While this is being effected the lower jaw is moved from side to side — from left to right, and right to left alternately — the articulation of the jaw being so constructed as to permit of this (see vol. i, p. 29). After the second and thorough chewing the food is conducted along a groove into the manyplies, which acts as a strainer, and thence into the rennet stomach, where gastric juice is poured upon it. The conditions of life under which the primitive ruminants existed account for the evolution of the complex stomach. The grass constituting their food would be most abundant on the plains, and here they would be exposed to the attacks of Carnivores. The power of rumination enables its possessor to rapidly obtain and swallow a large bulk of herbage, retiring afterwards to a place of safety, where the process of mastication can be completed at leisure. It is a commonplace that ordinary ruminants, just like Lions and Tigers among the Carnivora, find their food on or near the ground; though some of them, Goats, for instance, rear up on their hind-legs so as to browse on leaves and shoots otherwise out of reach. It has, however, recently been shown that a common South African antelope, the Blue-Buck (Cephalophus iyo THE FOOD OF ANIMALS monticola), can climb trees to some extent, for a number of them have been seen feeding among small branches about 12 feet from the ground. An extraordinary though well-known device, by which leaves and shoots at a considerable height from the ground are rendered available as food is afforded by the im- mensely long neck of the Giraffe (Camelopardalis giraffd) (see Fig. 419.— The Okapi (Okapia Johnstoni} vol. i, p. 1 20). Here, too, both lips and tongue are mobile, prehensile organs, and the latter is distinguished by its extreme length. The Okapi (Okapia Johnstoni) (fig. 419), recently dis- covered by Sir Harry Johnston in Central Africa, may broadly be described as a short-necked Giraffe, and is a kind of "half- way house " between its tall relative and other forms. The stuffed specimen which may be seen in the British Museum (Natural History) at South Kensington, possesses no horns, though there are bosses in the skull in places where horns might be expected (from comparison with Giraffe) to occur. This PLANT-EATING MAMMALS 171 specimen, however, is immature, and it is at present unknown whether the adult is hornless or not. No mention of the feeding habits of Ruminants would be complete without allusion to the way in which the Camel (Came IMS) is adapted, as regards drink, to desert conditions. The paunch here presents two swollen regions, resulting from a raising of the lining into folds, so arranged as to bound some 800 good-sized storage-cells for water. The opening into each of these can be closed by the action of a ring-muscle with which it is provided. It may be noted in passing that Camels possess upper front teeth, and that the manyplies is represented by a simple tube. The Hippopotamus, among non-ruminating Artiodactyles, is a voracious plant-eating form, contrasting in this respect with its omnivorous allies the Pigs. Some noteworthy features of the common kind (Hippopotamus amphibius) may be enumerated. The formidable tusk-like incisors and canines grow continuously throughout the life of the animal, and are forwardly directed, the latter being kept sharp by natural wear (see vol. i, p. 108). The arrangement is adapted for digging up water-plants and shearing off vast quantities of all sorts of vegetation. Once within the mouth the food is chewed by large cheek-teeth, the broad crowns of which wear into a characteristic double-trefoil pattern. The huge stomach ( 1 1 feet long) is four-pouched, and the intestine may be 180 feet long. Such a digestive tube is clearly suited to deal with an immense bulk of food. ELEPHANTS (PROBOSCIDEA) Elephants (see vol. i, p. 103) present a number of interesting adaptations to the herbivorous habit. Prehension is here the function of an immensely elongated nose or proboscis, which is a sort of exaggerated edition of the Tapir's snout. The muscle of which it is mainly composed is arranged in a very complicated manner, enabling all sorts of elaborate curving movements to be performed. A greater range of possibilities is here presented than in the Giraffe, for though in that animal the long neck enables leaves and shoots at a considerable height from the ground to be reached, grazing on the ground is rendered more difficult, and can only be effected by straddling out the long fore-legs in a particularly ungraceful attitude. The trunk of the Elephant, 1 72 THE FOOD OF ANIMALS on the contrary, can secure with equal ease foliage placed far above the mouth or tufts of grass and the like situated far below it, and it can also be used in the uprooting of small trees, should the upper parts of these take the fancy of its possessor. The tip of the proboscis is extremely sensitive, and so shaped as to be capable of comparatively difficult manipulations. The shape, however, is different in the two existing species, that of the Indian form (Euelephas] having a finger-like prolongation. Ele- phants are further distinguished by remarkable peculiarities in their teeth. Incisors are entirely absent, except two in the upper jaw, which form the offensive and defensive weapons known as tusks. There are no canines, and the cheek-teeth are enormous Fig. 420.— Grinders of African (A) and Indian (B) Elephants grinders with broad crushing crowns (fig. 420). These succeed one another from behind forward, quite unlike what happens in ordinary Mammals, and so large are they that, at most, parts of two are in use at the same time on either side of the jaw. There is also a complex folding, reminding one of what has been described for Ruminants. It may be understood by supposing the tooth to be thrown into a number of transverse folds with deep valleys between them, each fold consisting of hard dentine covered by still harder enamel, while the valleys are filled by comparatively soft cement resembling bone in nature. On looking at the crown of a worn tooth of the African Elephant (Loxodon)> the folds are seen to be comparatively few and somewhat lozenge- shaped, while in the Indian species they are much more numerous, relatively narrow, and somewhat wavy. It should further be noted that an elephant's grinder rises into position obliquely, so that the hinder folds are not at first brought into wear. The stomach is simple, but adaptations to vegetable food are present in the form of a large broad cczciim, while the intestines reach the length of from 1 06 to 125 feet, or to put it graphically, the intestines of three elephants, stretched out and placed end to end, would con- siderably more than suffice to mark out a course for a 100- yards race. THE INDIAN ELEPHANT (Eudephas Indicus} Elephants, the largest land animals now existing, are re- presented by two distinct kinds, the African Elephant (Loxodon Africanus] and Indian Elephant (Euelephas Indicus), native re- spectively to Africa and South Asia. These animals are adapted by their structure to vegetable food, which is secured by the pre- hensile trunk, this enabling them to seize food from the ground or from high above their heads with equal ease. Of front teeth only two upper incisors are present, which constitute the familiar tusks, serving as formidable defensive weapons. In adult elephants not more than four large and complicated grinding-teeth are in place at the same time. These consist of three sorts of material of different degrees qf hardness, and thus always present an effective ridged crown for breaking up the food. The ridges are much narrower and more numerous in the Indian than in the African species. The stomach is simple, but the intestines are of great length, in correlation with the nature of the food, which is more difficult to digest and absorb than the flesh diet of car- nivorous animals. THE INDIAN ELEPHANT (EUELEPHAS INDiCUS) DRAWN FROM THE LIFE BY F. SPECHT PLANT-EATING MAMMALS 173 SEA-COWS (SlRENlA) Sea- Cows are herbivorous mammals which have taken to an aquatic life, feeding along the shore and, in one species, travel- ling up rivers for a considerable distance. Only two forms now exist — the Manatee and Dugong. The Manatee (Manatus] (see vol. i, p. 101) is found on both coasts of the tropical parts of the Atlantic, and lives for the most part in the larger rivers, which it may ascend for hundreds of miles. Only fore-limbs are present, and though these help to some extent in seizing food, the chief prehensile organ is the upper lip, which is well developed and of remarkable shape. Deeply excavated in the middle, it possesses a sort of pad on each side, and the two pads can be brought together for the purpose of grasping food, which is held fast by their bristly surfaces, and then drawn back into the mouth. Canine teeth are entirely absent, and the adult possesses no incisors, though in the young animal vestiges of these are to be found under the thick horny plates with which the front of the jaws is armed. The roof of the mouth is furnished with similar plates. The cheek-teeth are in the form of grinders, with broad, square crowns marked by transverse ridges. Of these teeth 44 in all are devel- oped, but not more than 24 of these are as a rule in use at once, for by the time the hinder ones are in place those in front of them have dropped out. The Dugong (Halicore] (fig. 421) is essentially a marine animal, ranging round the shores of the Indian Ocean to the coast of Australia. The upper lip is not specialized for prehen- sion as in the Manatee, but the lower lip is relatively larger and much swollen. One marked peculiarity is found in the front parts of the jaws, these being bent abruptly downwards. As before, they are armed with crushing horny plates. Incisors are better developed than in the Manatee, for two are present in the male in the form of long sharp tusks. These are developed within the jaw of the female, but never cut the gum. The re- maining teeth are simple rounded molars with flat, smooth, rounded crowns. Not more than twenty are present at any time, and they appear to be degenerating structures, as shown by the absence of enamel. It is interesting in this connection to observe that a large toothless Sirenian, Rhytina, inhabited the coasts of the 174 THE FOOD OF ANIMALS Behring Sea until 1768, when it became extinct, having been exterminated for the sake of its flesh. The horny plates present in Manatees and Dugongs were here of greater extent, to com- pensate for the complete absence of teeth. Fig. 421. — The Dugong (Halicore dugong} GNAWING MAMMALS (RODENTS) Rodents include a vast number of widely -distributed small animals, of which the great majority feed entirely on vegetable food. A Rabbit (Lepus cuniculus) or Hare (L. timidus] (fig. 422), illus- trates very well the adaptations to a vegetable diet exhibited by the members of the order. Comparatively few teeth (twenty- eight) are present, the limited number being accounted for by the entire absence of canines and reduction of incisors. All the teeth grow continuously throughout life, in correspondence with which peculiarity they do not narrow into " fangs " within the substance of the jaws, but are of uniform thickness throughout. Two long chisel-edged incisors are present in the front of each jaw, and it is these which constitute the gnawing structures characteristic of the entire order. We have seen how the complex grinding- teeth of Ruminants, &c., are kept rough by being made up of materials of different degrees of hardness; this is a case where PLANT-EATING MAMMALS 175 a sharp edge is maintained by similar means, for the front side of each incisor is covered with a thick coat of hard enamel, at the back of which comes a softer mass of dentine. Hence the effect of wear is to produce and maintain a bevelled or chisel- like edge. As these teeth are continually growing it is necessary that they should be kept worn down by constant use, and should a rodent be so unfortunate as to lose one of its front teeth, its Fig. 422. — Hares ^Lepns timidus) fellow will have nothing to do to wear it down, and, continuing to grow, will first prove a hindrance to feeding, and then stop it altogether, sometimes even piercing the skull of its owner. The same thing happens (fig. 423) if these teeth are misplaced. In Rabbits, Hares, and their immediate allies, but not in re- maining Rodents, two very small reduced incisors are present behind the large ones, but it is doubtful if these are of much use, and they may be looked upon as structures which are on the downward path of degeneration. The Rabbit's cheek-teeth are prismatic in form, and their broad grinding crowns are crossed by enamel ridges which, as in many other cases, slant differently above and below, so that when the upper and lower teeth are brought together the opposed ridges cross one another. A further adaptation to the plant-eating habit is found in the 1 76 THE FOOD OF ANIMALS shape of the projections (condyles) by which the lower jaw is united to the skull. These are elongated from before back- wards, which permits of a movement in the same direction (see vol. i, p. 28). We may further note the great length of the digestive tube, fifteen or sixteen times that of the body, and further, though the stomach is simple, there is a very large and complex ccecum at the beginning of the large intestine. The salivary glands Fig. 423.— Abnormal Skull of Hare (Lcpus thnidiis] are extremely well developed, the secretion of these acting upon the abundant starch present in the food. DORMICE AND SQUIRRELS. — The structure of the Rodentia is on the whole so uniform that it would be tedious to review them in detail, and it will perhaps be enough to indicate a few points of special interest. We may, for example, note that while hares and rabbits feed on the surface of the ground, Dormice (Myoxidce) and many Squirrels (Sciurida) are of arboreal habit, this being, as we have seen in many other cases, a favourite device for extending the range of feeding operations. It may, indeed, be taken as a general principle, that where food is to be found there will also be found animals provided with special means of getting at it. In these climbing forms, too, the fore-paws are used for holding the food, despite the fact PLANT-EATING MAMMALS 177 that the thumb is much reduced in size. The cheek-teeth are possessed of roots, and though both squirrels and dormice are mainly vegetarian, they also raid birds'-nests for the sake of the eggs and young. BEAVERS (Castorida) deserve mention as regards their food, which consists of roots, bark, and young wood. They can even cut down trees by means of their immensely strong incisors, and do a great deal of damage in this way. Their cheek-teeth are more complex than in the forms so far mentioned, being better provided with enamel folds. True RATS and MICE (Murid