ZOOLOGICA SCIENTIFIC CONTRIBUTIONS OF THE NEW YORK ZOOLOGICAL SOCIETY VOLUME 54 • ISSUE 4 • WINTER, 1969 PUBLISHED BY THE SOCIETY The ZOOLOGICAL PARK, New York Contents PAGE 8. Aspects of Melanism in Acanthopterygian Fishes. By C. M. Breder, Jr. Plate I; Text-figures 1-6 105 9. Color Pattern of the Eastern Pacific Spotted Porpoise Stenella graft mani Lonnberg (Cetacea, Delphinidae). By William F. Perrin. Plates I- VII; Text-figures 1-3 135 Index to Volume 54 151 Manuscripts must conform with Style Manual for Biological Journals (American Institute of Biological Sciences). All material must be typewritten, double-spaced. Erasable bond paper or mimeograph bond paper should not be used. Please submit an original and one copy of the manuscript. Zoologica is published quarterly by the New York Zoological Society at the New York Zoological Park, Bronx Park. Bronx, N. Y. 10460. and manuscripts, subscriptions, orders for back issues and changes of address should be sent to that address. Subscription rates: $6.00 per year; single numbers, $1.50, unless otherwise stated in the Society's catalog of publications. Second-class postage paid at Bronx, N. Y. Published March 26, 1970 © 1970 New York Zoological Society. All rights reserved. ZOOLOGICA SCIENTIFIC CONTRIBUTIONS OF THE NEW YORK ZOOLOGICAL SOCIETY VOLUME 54 • 1969 • NUMBERS 1-9 MAY 4 1970 PUBLISHED BY THE SOCIETY The ZOOLOGICAL PARK, New York NEW YORK ZOOLOGICAL SOCIETY The Zoological Park, Bronx, N. Y. 10460 Laurance S. Rockefeller President John Pierrepont T reasurer OFFICERS Robert G. Goelet Executive Vice-President Chairman of the Executive Committee Henry Clay Frick, II Vice-President Howard Phipps, Jr. Secretary Edward R. Ricciuti Editor & Curator, Publications & Public Relations EDITORIAL COMMITTEE Robert G. Goelet Chairman F. Wayne King William G. Conway Donald R. Griffin Hugh B. House Joan Van Haasteren Associate Editor Peter R. Marler Ross F. Nigrelli George D. Ruggieri, S.J. William G. Conway General Director ZOOLOGICAL PARK William G. Conway . . . Director & Curator, Ornithology Hugh B. House .... Curator, Mammalogy Grace Davall . . Assistant Curator, Mammals & Birds Walter Auffenberg . . . Research Associate in Herpetology Joseph Bell . . Associate Curator, Ornithology F. Wayne King .... Curator, Herpetology William Bridges . Curator of Publications Emeritus John M. Budinger . . . Consultant, Pathology Ben Sheffy Consultant, Nutrition James G. Doherty . Assistant Curator, Mammalogy Donald F. Bruning . Assistant Curator, Ornithology Joseph A. Davis, Jr. .... Scientific Assistant to the Director AQUARIUM Ross F. Nigrelli Director Christopher W. Coates . . . Director Emeritus Nixon Griffis .... Administrative Assistant Jay Hyman Robert A. Morris Curator U. Erich Friese Assistant Curator Louis Mowbray . Research Associate in FieldBiology Consultant Veterinarian OSBORN LABORATORIES OF MARINE SCIENCES Ross F. Nigrelli . . . Director and Pathologist Martin F. Stempien, Jr. . . . Assistant to the Director & Bio-Organic Chemist George D. Ruggieri, S.J. . . . Coordinator of Research & Experimental Embryologist William Antopol . . . Research Associate in Comparative Pathology C. M. Breder, Jr. ... Research Associate in Ichthyology Jack T. Cecil Virologist Jay Hyman Harry A. Charipper . . Research Associate in Histology Kenneth Gold Marine Ecologist Myron Jacobs Neuroanatomist Klaus Kallman Fish Geneticist Vincent R. Liguori Microbiologist John J. A. McLaughlin . . Research Associate in Planktonology Research Associate in Fish Endocrinology Martin P. Schreibman Research Associate in Comparative Pathology INSTITUTE FOR RESEACH IN ANIMAL BEHAVIOR [Jointly operated by the Society and The Rockefeller University, and including the Society's William Beebe Tropical Research Station, Trinidad, West Indies] Peter R. Marler Director & Senior Roger S. Payne Research Zoologist Research Zoologist Fernando Nottebohm . . . Research Zoologist Richard L. Penney Assistant Director George Schaller Research Zoologist & Research Zoologist Thomas T. Struhsaker . . . Research Zoologist Donald R. Griffin . . . Senior Research Zoologist C. Alan Lill Research Associate Jocelyn Crane .... Senior Research Zoologist Paul Mundinger Research Associate O. Marcus Buchanan .... Resident Director, William Beebe Tropical Research Station Contents Issue 1. July 25, 1969 PAGE 1. Laboratory Studies on Life-span, Growth, Aging, and Pathology of the Annual Fish, Cynolebias bellottii Steindachner. By Robert K. Liu and Roy L. Walford. Plates I-III; Text-figures 1-4 1 2. Direct Measurement of COL> Production During Flight in Small Birds. By John M. Teal. Text-figure 1 17 3. A Study of Experimentally Induced Endocytosis in a Teleost. I. Light Microscopy of Peripheral Blood Cell Responses. By Eva Lurie Weinreb and Stanley Weinreb. Plates I-III; Text-figure 1 25 Issue 2. November 17, 1969 4. Some Mexican and Central American Land Snails of the Family Cyclo- phoridae. By Fred G. Thompson. Plates I-VII; Text-figures 1-14 35 5. The Underwater Song of Erignathus (Bearded Seal). By Carleton Ray, William A. Watkins, and John J. Burns. Plates I-III; Text-figure 1; Phonograph Disk 79 Issue 3. January 9, 1970 PAGE 6. Intact Killifish (Fundalus heteroclitus) as a Tool for Medically Oriented Study of Marine Neurotoxins. By John J. A. McLaughlin and Russell J. Down. Plates I-II; Text-figure 1 85 7. Studies on the Biology of Barnacles: Parasites of Balanus eburneus and B. bcilanoides from New York Harbor and a Review of the Parasites and Diseases of Other Cirripedia. By Lucie Arvy and Ross F. Nigrelli. Plate I 95 Issue 4. March 26, 1970 8. Aspects of Melanism in Acanthopterygian Fishes. By C. M. Breder, Jr. Plate I; Text-figures 1-6 105 9. Color Pattern of the Eastern Pacific Spotted Porpoise Stenella graffmani Lonnberg (Cetacea, Delphinidae). By William F. Perrin. Plates I-VII; Text-figures 1-3 135 Index to Volume 54 151 8 Aspects of Melanism in Acanthopterygian Fishes C. M. Breder, Jr.* ( Plate I; Text-figures 1-6) Teleost fishes may show a strong melamism against a light background. This condition is found chiefly in young fishes of the families Carangidae, Sapridae, Sciaenidae, and Ephippidae during the warm half of the year. Social attitudes and locomotor behavior change with this darkening, including a solitary, quiescent, and agonistic attitude. This behavior mitigates the conspicuousness of this black phase, which has evidently been induced by former residence on a very dark background. This may return quickly to a light phase or be retained for a period of some weeks because of certain interactions within the neuro-endocrine system which control the pigment cells responsible for this phenomenon. The size at which fishes outgrow is related to the light intensity and water turbidity. Introduction It has been adequately shown that some spe- cies of acanthopterygians may be found in an intensely black condition although liv- ing over an extremely light background (Breder, 1946, 1948, 1949a, 1955, and 1959; and Breder and Rasquin, 1950 and 1955). This blackening is brought about by the usual piscine mechanism of pigment control, first by disper- sion of the melanin granules contained within the melanophores, followed by the development of additional melanophores, leading to melan- ism. In this dark phase these fishes are solitary and quiet, usually “freezing” on approach, while in the lighter phases they are gregarious, active, and flee on approach. The situations which lead to the observed consequences are analyzed herein. Help in collecting the information contained herein has come from many quarters and is chiefly noted in context. Special mention is given here, however, for the great assistance rendered by Dr. Eugenie Clark and her daugh- ter, Hera Konstantinu. Both undertook consid- erable field work, and in addition Dr. Clark sup- plied many details of the area with which she is intimately familiar. Mr. Louis Godey, an NSF * The American Museum of Natural History, New York, New York 10024, and Mote Marine Laboratory, Sarasota, Florida 33581. summer student at the Cape Haze Laboratory, working under the direction of Dr. Clark, ob- tained valuable statistical and other data during the 1962 season in the Sarasota area. The Cape Haze Marine Laboratory (the Mote Marine Laboratory since 1967) provided needed facili- ties for the prosecution of this study. These facilities have been continued through the cour- tesy of the present director, Dr. Perry Gilbert. The fine efforts of Miss Sarah L. Page, work- ing with the author as a Lincoln Ellsworth Field Assistant, of the American Museum of Natural History, went far toward filling in needed information. The work was supported in part by a grant (NSF-G-19382) from the National Science Foundation. Otherwise support was provided by the American Museum of Natural History. The Natural Occurrence of Melanistic Individuals Because of the general sensitivity of fishes to the shade and color of their backgrounds, pre- sumably all teleosts with dermal or epidermal melanophores have the potential to darken their colors in response to a dark background. How- ever some species cannot, or do not, do so to any noticeable extent and many can carry the condition only to a point far short of becoming black. Some cave fishes, but not all, have evi- dently lost their ability to produce melano- phores, even when exposed to light. At least 105 106 Zoologica: New York Zoological Society [54:4 certain of them do not produce melanophores, even though kept in light for generations ( Breder and Rasquin, 1947, and Rasquin and Rosen- hloom, 1954). At the other extreme, various deep sea fishes have a more completely developed melanism than any others. These too are living in dark- ness, except that a vast variety of luminous invertebrates and melanistic fishes prevent the ocean abysses from being totally lightless. Sig- nificantly many of these forms, unlike the blind fish of fresh water caves, have not lost their eyes. No luminous aquatic creatures have been yet discovered in subterranean fresh waters. These conditions have usually been considered as basic to the extreme pigmentary differences between cave and abyssal fishes. By contrast there are few epigeal fishes, in either fresh or salt water, that are either pig- mentless or completely black. So far as known, these few are all generally able to adjust their pigments, when appropriately stimulated, to patterns more usual in surface waters. The hy- pogeal forms, marine or fresh water, apparently lack this ability to any considerable degree, as indicated above, and are thereby confined to a single pigmentary appearance. The following accounts of field observations are limited to fishes that can show a completely or almost completely black aspect, in places subject to natural illumination, and in which they appear as solitary individuals. Black fish which appear in lighted environments only in aggregations are not included. Data and refer- ences to these may be found in Breder (1959) and Randall and Randall (1960). Because of the nature of field notes, some part of the following matter is fragmentary and anecdotal, but in most instances represents all the existing information. These data are nevertheless necessary, as will be apparent in the discussion. The principal cases The following cases are those which are used in support of the views expressed in the dis- cussion. Trachinotus falcatus (Linnaeus) The presence of small black individuals in Sandy Hook Bay, New Jersey, was reported by Breder (1923) and noted by Nichols and Breder (1926). These were collected October 4, 1922, on a light sandy beach, littered with bits of weed and other debris. They were described as a smooth velvety black with hyaline fins. All were near 24 mm in standard length. Two were kept in an aquarium for a few weeks during which time they became silvery,1 resembling in color the much more abundant young of Trachinotus carolinus (Linnaeus). The latter vary very little from a generally silvery color, so far as known, except for becoming very dusky in certain aquariums, as is reported by Fields (1962) for sizes of from 15 to 30 mm. The two young T. falcatus differed from any of the small black fishes encountered in that the iris was a ruby red. Subsequent years others were seen at the same place, as noted by Breder (1926, 1928, and 1929). None of these exceeded 35 mm in s. 1. and it seemed that they spon- taneously lost the dark phase, usually at some- what less than that size. The red irises always became silvery as the dark pigment waned. Various regional lists, some published before the above notes but based on preserved mate- rial, include notes on other pigmentary varia- tions in these small fishes: Meek and Hildebrand (1925) on Panama material; Hildebrand and Schroeder (1928) on material from Chesapeake Bay; and Fields (1962) on material from Mas- sachusetts to Haiti. All show illustrations of this dark stage, the first of a 48 mm example still evidently quite dark, the second of an 18 mm fish and the third of an 16 mm fish. The following quotation is from the 1928 paper: “Very young (40 mm and less in length) densely punctulate with rusty dots, giving them the color of a dead leaf; dorsals and anal very dark; caudal pale.” The 48 mm example is described as densely punctulate with dark points. There can be little doubt that at least some of these were very dark or black in life. Longly and Hildebrand (1941) mention rather similar col- oration of a 15 mm individual taken in floating Sargassum at the Dry Tortugas, Florida, and that others from 9 mm to 1 1 mm varied in color from nearly black to brownish with dark punctulations and that the soft parts of the vertical fins were abruptly colorless. Randall and Randall (1960) reported individuals of about 16 mm, taken from St. John, Virgin Islands, in July, as black and bronze. These fish had the flexed tail and other typical be- havior items Randall and Randall considered as causing them to resemble leaves. Fields (1960) described at length the many color vari- ants these young fishes may display. Beebe and Tee-Van (1928), and nearly all authors with 1 Fields (1962) reported that similar silvery young placed in an indoor aquarium tended to darken, but would return to silvery if the aquarium was placed in direct sunlight outdoors. In a personal communication, Dr. Phyllis Cahn independently reported a similar re- versible condition while working with this species at the Cape Haze Marine Laboratory. 1969] Breder: Aspects of Melanism in Acanthopterygian Fishes 107 comparative series, commented on the extreme variability of the young of this species. Earlier these small sizes were reported as often common at Woods Hole, Massachusetts, from July to October (Sumner, Osborn and Cole, 1867). They make no mention of the col- oration of the young, as their paper is limited to a list of forms found. Neither do other early lists of fishes from that area, such as Storer (1867), Baird ( 1873), Smith (1898), and Kendall (1908), nor the more general treat- ments of Goode (1884) and Jordan and Ever- mann (1896). However Bean (1888) gave a largely forgotten illustration of a dark colored T. falcatus, re-published by Fowler (1907). Both authors reported collecting small, dark colored examples at Beesley’s Point, New Jer- sey, a favorite collecting site in those days. All of the fishes ranged from 1 inch to 2(4 inches in length, presumably total lengths. Bean wrote, “An individual, 1 Vi inches in length, taken at Beesley’s Point, September 2, was mainly silvery when seined, but on being placed in a small aquarium almost instantly became brown, the dorsal and anal nearly black. On the ventrals, the anal spines and the anterior tip of the anal fin, the usual vermillion shading into orange.” All these cases mention few individuals com- pared with quantities of the constantly school- ing T. carolinus that were usually noted as silvery, if color was mentioned at all. Fields (1962) discussed at length the color variations in the young stages of T. falcatus and com- pared them with the lack of such pronounced chromatic variety in both T. carolinus and glaucus. The T. falcatus mentioned by Breder (1962a), were collected on April 25, 1961, in Lemon Bay, on the Florida west coast. It was not noted in that publication that they were in a fully black phase. They were about 20 mm in s. 1. This is the earliest date recorded for the appearance of the dark phase. By December on this coast the median length of T. falcatus is nearly 60 mm s. 1. (Springer and Woodburn, 1960), and black ones are rare by October. T. falcatus and Chaetodipterus often appear together. When both species are of the above- mentioned sizes and in the black phase there is sometimes some difficulty in distinguishing one from the other. Therefore, the following key is given. The non-metric characters in the key are sufficient to distinguish the two as they swim in an aquarium. A. Spinous dorsal highest in the middle, 4th spine longest, dorsal VII, 19-20; the spines appear as though radiating from a center; a long spine at angle of inter- opercle, clear and glass-like; pelvics under and shorter than pectorals; caudal forked; a vertical from maxillary passes through eye, tangent to or before the pupil. Trachinotus falcatus Text-fig. 1. AA. Spinous dorsal highest at front, 1st spine longest, dorsal edge level in middle, 5th to 9th spines equal in length and paral- lel, dorsal IX, 23; no long clear spine on interopercle, except in the smallest sizes there are three short spines, the middle one at angle; pelvics in advance of and larger than pectorals, caudal bluntly pointed, eye behind a vertical from maxillary. Chaetodipterus faber Text-fig. 2. 2 Lagodon rhomboides (Linnaeus) On October 30, 1959, along the shore of Lemon Bay, what appeared to be a piece of black “trash” resolved itself into a small fish of about 15 mm. The beach had been recently storm-swept of most litter. Only a few odd bits of black decaying leaves were noticeable. These approximated the size of the fish. The amount of disturbance incident to wading about in the setting of a small trap did not cause the fish to move off. It merely stayed fairly close to one leader of the trap. After some observations on its general behavior, it was dipped up in a small aquarium dip-net. The fish made no attempt to escape capture. When placed in a large jar of water, it was immediately apparent, despite the nearly solid black pigmentation, that the fish was a young Lagodon. The caudal, posterior dorsal and anal tips and the pectorals were perfectly transpar- ent. It held itself curved rigidly and maintained its position by activity of the transparent pec- torals. Almost immediately it began to bleach and show the usual pattern of bars. On release it swam off slowly, but did not join an aggrega- tion of similarly sized Lagodon that hovered about not more than four feet away. All these fish were in their light and sand-matching colors and therefore very difficult to distinguish. They were active, alert, and not to be caught by a small dip-net. When attempts at catching the fish were made they formed a temporary fright school. Menticirrhus The four Atlantic species of this genus, at least, appear to be very closely related and all 2 The light nuchal band shown in this illustration is typical of this species when passing into or out of the black phase and is absent in T. falcatus. 108 Zoologica: New York Zoological Society [54:4 of them have young which sometimes show melanism. Therefore the following sparse notes on the four species are treated together. All are commonly found in small aggregations in the 20 to 30 mm s. 1. range, which usually do not number over two dozen individuals. They are distinctly fishes of light sandy beaches, typically in a light sand-matching color. The pattern of divergent bars, normal to some spe- cies, is frequently very faint or absent. Alter- nately, they are found in a melanistic state, either as solitary individuals or usually as one black fish to a school. In no other species have black individuals been found in schools of other- wise lightly pigmented fishes. When alone they curve the body and do not attempt to flee, in the manner common to other species. Menticirrhus focaliger Ginsburg. On Novem- ber 22, 1959, shortly after the Lagodon was found, another nearly solid black fish of about 32 mm was seen not far from some fragments of “trash,” near the same place. This fish re- sorted to immobility and made no attempt to elude capture. After being placed in an aquar- ium for closer scrutiny, there was no evidence of blanching, unlike the Lagodon. This fish dis- played the posturing typical of the melanistic fishes. The caudal fin, pectorals and the posterior edge of the anal fin were fully transparent. The following morning the fish was as dark as when first found. It usually hovered near one of the corners of the aquarium, which were black on their interior surfaces. There was nothing in the aquarium but the fish and water. This fish sel- dom rested on the nearly black slate aquarium floor; it hovered in mid-water by use of its large pectoral fins, while the body and tail were mostly arched rather stiffly to one side. Fishes of the genus Menticirrhus normally sink to the bottom when not actively swimming, and un- like most other members of the family Sciae- nidae they lack a swim bladder. It clearly took continuous physical exertion for the fish to keep itself away from the bottom. The lack of a tendency to flee from approach- ing objects was demonstrated nicely by this individual. When approached by a hand or a small stick, it merely stiffened the arch in its body and fluttered the nearly invisible pec- toral fins faster. On very close approach of any small object, it backed away just far enough to escape physical contact. The following day this fish was returned to the sea at the place it was found. It was still in the black phase and acted accordingly, staying at the place of release. The sea-floor litter was less abundant than at the time of capture. The fish was watched closely for about half an hour, during which time it appeared to be searching Text-fig. 1. Trachinotus falcatus. Three renderings of young fish in the black phase. Upper, after Bean (1888) circa 20 mm s.l. Middle, after Hildebrand and Schroeder ( 1928) 18 mm. Lower, after Fields ( 1962) 16.9 mm. for a suitable place to station itself, moving about slowly, after the fashion of such fishes, and coming to rest some distance from various bits of trash, usually more than one foot dis- tant. When it left the vicinity of one place, it would move along through open water, close to the bottom, head down and with the body turned partly on its side, almost precisely as has been described for much larger Chaetodipterus by Breder and Rasquin (1955). In about an hour the fish had vanished, which may mean that it had moved out of range or had simply disappeared within our visual range. The latter is not the least unlikely for in situations involv- ing such backgrounds, obliteration of the fish is to be expected. 1969] Breder: Aspects of Melanism in Acanthopterygian Fishes 109 Text-fig. 2. Chaetodipterus jaber. Circa 20 mm s.l. After Hildebrand and Cable (1938). Springer and Woodburn (1960) mentioned the following, concerning fishes in the Tampa Bay area, "It was noticed that the young of M. focaliger under 22 mm exhibited two dis- tinct types of color pattern. In one type the entire specimen except for portions of the fins is deeply and uniformly pigmented. In the other dark and light areas appear over the specimen in approximation of the adult coloration.” Dr. R. W. Harrington, who has collected many small shore fishes on the Florida east coast, wrote as follows in a personal communi- cation in connection with these pigmentary con- ditions. “Have never seen coal-black Lagodon rhomboides but I have collected one small Men- ticirrhus saxatiiis that was dark brown among a large group of M. littoralis which were pale, over a sandy bottom.” Many authors not concerned with the present interests have had occasion to note the dark phase of these fishes. Hildebrand and Cable (1934), for instance, not only mention, but also figure dark individuals of similar sizes of M. americanus (Linnaeus), M. saxatiiis, and M. littoralis ( Holbrook ) . Menticirrhus saxatiiis (Linnaeus). Earlier notes on this species, not concerned with pig- mentation, yielded the information given in Table I and in Text-fig. 3. These notes, on fishes in Sandy Hook Bay, New Jersey, were used in part by Nichols and Breder (1926) for other purposes. As suggested in Table I, there were successive waves of young fishes entering the bay from later spawnings, which accounts for variations in the graph shown as Text-fig. 3. Especially marked is the small isolated group in October which has not been integrated into the other data because of its obvious difference in range of sizes. Although no records were kept at this time on the numbers of black indi- viduals encountered, it was noted that they were found only in the smaller sizes, between 10 and 30 mm, and were few in number. This agrees well with the descriptions and figures of Hilde- brand and Cable ( 1934), who in presenting life history data showed that the dark phase was found in stages down to 10 mm but that this phase disappeared when the fish reached from 30 to 35 mm in length. Hildebrand and Cable made the following comment: “All the speci- mens at hand were caught among black, partly suspended vegetable debris, which they re- semble in color. It seems probable that these fish are darker than they would have been had they been taken in a different environment.” In another place they wrote, "The spinous dorsal and ventral fins are black; the pectoral fins are colorless; the second dorsal and anal have at least a partly black base, the rest of these fins being colorless; and the caudal is colorless, ex- cept for a black blotch on the base . . This statement could stand almost unaltered for any of the various species of small black fishes dis- cussed here. Similar comments were made for both M. americanus and M. littoralis. Evidently these two species may pass through the black phase at just about the same sizes as does M. saxatiiis. This seems to also apply to M. focaliger. Apparently the black stage appears only in the presence of blackish fragments of trash in the sea. Dr. D. E. Rosen, in a personal communica- tion, stated that on the south shore of Long Island, New York, he saw a black M. saxatiiis become light sand color in a moment. Chaetodipterus jaber (Broussonet) This species is the only one that has been studied in any detail in respect to melanism as a normal reactive process. Also it happens to Table I. Occurrence by Date and Size of Young Menticirrhus saxatiiis in Sandy Hook Bay, New Jersey Date Number of spec. Standard length Min. Mean S' mm Max. Aug. 2 1 1923 42 9 1 — 48 — 16 3 38 48 64 19 17 47 89 92 Oct. 9 4 4 9 12 19 80 58 89 123 Sept. 24 25 1924 90 95 100 July 29 2 1925 29 29 30 Aug. 13 2 39 48 55 Sept. 3 i - 115 — Oct. 1 15 100 125 150 110 Zoologica: New York Zoological Society [54:4 Text-fig. 3. Menticirrhiis saxatilis. Presumptive growth curve based on data from Sandy Hook Bay, New Jersey, in Table I, 1923 through 1925. Large circles indicate extremes of size range or single fish in s.l. Small circles indicate means of sample. See text for explanation of group near base line in Oc- tober. The range between the two dotted horizontal lines shows the sizes at which the black individuals may be expected. have a fair amount of its life history recorded. Therefore the treatment here has been extended in order to establish more fully the relationship of inverse pigmentation to development and life history. Spawning clearly takes place in spring and is earlier southward. Reproductive activity is not known north of Virginia, but individual fishes are found as stragglers, especially in the late summer, to Massachusetts, but not north of Cape Cod. The eggs are buoyant, non-adhesive, and average about 1.25 mm in diameter. They hatch in about 24 hours at a temperature of 80° F, according to Ryder (1887). All indica- tions are that spawning takes place well offshore. As noted above, Hildebrand and Cable (1938) found small fry offshore but none were found under about 15 mm in inshore waters near Beaufort, North Carolina. Twenty-eight hours after hatching the larvae measure about 3.5 mm and evidently show no indication of any pig- mentary over-development. Nor does anything indicate that Ryder had any knowledge of the black phase, which first appears at about a length of 9 mm as indicated by Hildebrand and Cable.3 Strangely, Ryder noted that the larvae sNone of the earlier papers mentioned under Trachi- notus noted anything about the black phase of Chaeto- dipterus. might be phosphorescent, a condition which no one since that time has mentioned, but appar- ently no one has had living larval Chaetodipterus since then. Springer and Woodburn (1960) indicated a spring and summer spawning season in the Gulf of Mexico, a condition which all our data sup- ports. The data of Gunter ( 1 945 ) , Reid ( 1 945 ) , and Springer and Bulbs (1956), together with their own material and collections, lead Springer and Woodburn to believe that Chaetodipterus in the Gulf spends its winter season mostly in offshore waters. We differ in no way with this view, based both on present work and prior experience in Pine Island Sound in the 1930s. Kilby (1950) and Reid (1954) both took small individuals running from 20 mm to 30.5 mm in length, at Cedar Key in June and July and one in December of 46 mm. Springer and McErlean ( 1962) took examples at Matacumbe Key during October, November, and December that averaged 25 mm, 36 mm, and 42 mm respectively. The black phase of Chaetodipterus was first described in detail by Breder (1946). The fishes reported then were nearly all of a size of about 9 mm. They were collected on the following dates in 1942 in the quantities indicated below. June 1 1 2 12 4 13 5 July 3 1 5 1 A few others were seen on the above days. No others had been seen on four previous summers in the same place. Palmetto Key, Pine Island Sound, Florida. In view of their subsequent rather erratic appearance at other places, it may be that the real reason for not seeing them before 1942 at Palmetto Key was this erratic- ness, and not, as thought at the time, merely because of their inconspicuousness against the background on which they were found. After June 11, noted above, these little fishes were sought energetically every day to July 11, with no success after July 5. Similarly there is great variation in the num- bers of small black Chaetodipterus which appear at Siesta Key from one season to another. The numbers which appeared there in 1962 far ex- ceed those of any other year or at any other known location where they may be found. This comment is based on the combined observations of a number of persons, chiefly Dr. E. Clark, from 1960 through 1967. Fortunately in the year of greatest abundance it was possible to have the assistance of Mr. Louis Godey, whose notes have yielded the general frequency in 1969] Breder: Aspects of Melanism in Acanthopterygian Fishes 111 time, which is given in Table II, as well as their general distribution, which is shown in Text- fig. 4. 4 According to Dr. Clark, the two previous years were notable for the general presence of considerable numbers of fishes in the black phase. After that time, although fair numbers were present in 1963, the total fell off to a single fish caught in 1967. That year Mr. Fred Small, of the Mote Marine Laboratory staff, reported some of these fishes on Anna-Maria Key, but that was all. Collecting efforts were continued through 1967, but radically fewer fishes were seen. The large influx of small black Chaetodipterus along the Gulf shore of Siesta Key is evidently influenced by the local configuration of the shoreline, but is probably primarily established by the nature of the circulation of Gulf water. Chew ( 1955) defined a convergence mechanism on the Florida west coast which, with the off- shore circulation, apparently produces a shore concentration of water-borne materials. He holds this effect responsible for the shoreward movement of the “red tide” and the fish kills that result. At the time of these concentrations of black Chaetodipterus, there was no “red tide.” Such small fishes are among the first destroyed in the area of an outbreak of this toxic phenomenon. Table III shows that the black phase was not seen on the Gulf coast of Florida earlier than April 26, nor later than October 18, while on the Atlantic side the black phased individuals were first observed on June 6 and the latest on August 16. These data do not suggest any marked seasonal differences in the time of appearance of the black phase between the Gulf and Atlantic sides of Florida. The smallest fish in the black phase seen on the Gulf side was 8.2 mm in length; on the Atlantic side it was approximately 9 mm. The largest in the black phase in the Gulf was 74 mm, and none nearly that size have been reported from the Atlantic coast. Much of this is evidently a matter of insufficient records. In the Bahamas, the black phase occurs in fish at least up to 300 mm in length, while the smallest reported in black phase is 76 mm long. The following additional instances are given to clearly indicate that this type of behavioral and physiological melanism, while erratic in local appearance, is not a particularly rare phenomenon. Reid (1954) reported that young of approxi- 4 With the Chaetodipterus were some similar sized Trachinotus falcatus also in their black phase, but they were not numerous. See also under that species for related data. mately 20 mm were taken at Fort Myers Beach and, . . were colored a rich black, and with a perfectly transparent caudal fin, were found very close to barnacle-covered piles. These were also as close to floating wrack . . .” In a personal communication, Dr. R. W. Harrington reported as follows: “Saw Chaeto- dipterus faber June 6, 1955, in shallow water over a mixed sandy and flocculent bottom to one side of the mouth of the canal (large ditch) draining our laboratory, Entomological Re- search Center, Vero Beach, Florida, i.e., where the canal debouches into the shallows of the Indian River. I recall how hard they were to see and how dark they were, but have no fur- ther notes. We were able to take only three in the seine (range 16-32 mm s. 1.) and have col- lected only one specimen since (in a shallow turbid embayment of Indian River transected by the St. Lucie County line, among patches of algae, Halodule, and Ruppia, June 7, 1956, 18 mm s. 1.)” The following cases of the occurrence of similar small black individuals were reported by Dr. Clark. Gasparilla Island. Seen on the Gulf side in about eight feet of water, September 1955. Aside from the North Carolina records (Hilde- brand and Cable, 1938) of specimens collected near the bottom by tow nets, which surely occurred in much deeper water, the above seems to be the deepest that these black-phased speci- mens have been collected. These authors noted that all young fish under 15 mm were taken in outside waters. Table II. Occurrence of Young Chaetodipterus in the Black Phase on Siesta Key, Florida, During 1962 Date Nos. seen 1 July 1 0 2 0 5 2 12 10/sq.ft. Greater numbers were seen between the above date and the following: Aug. 1 10/ sq. ft. 6 1 8 2 12 02 14 0 15 1 'These observations were all made at the localities indicated in Text-fig. 4. : During Aug. 11 and 12, “large numbers" were re- ported from Sanibel Island. 112 Zoologica: New York Zoological Society [54:4 Mote Marine Laboratory (Siesta Key). At this locality black-phased Chaetodipterus were seen each year as indicated earlier and usually some Trachinotus falcatus. Table III lists the sizes found with related dates, locality, and the sources of information. These are from the literature and by way of personal communication, while entries without source indication are new. Total lengths are used throughout unless otherwise noted, but many of the older references do not specify their usage. For present purposes these differences are not critical. Appropriate information in Table III, plotted against time, forms a generalized pre- sumptive growth curve and is shown as Text- fig. 5. Although the data ranges from Texas to New Jersey, a not unreasonable growth curve is suggested.5 Other data, including that of the occurrence of gravid females and breeding males, are also indicated. With this condensed life history data as a background, the range of occurrence of the black phase is indicated. None over a length of 35 mm have been found in the comparatively turbid water of Florida’s Gulf coast, but in the clearer waters of the Bahamas the black phase and the accompanying charac- teristic attitudes have been found in fishes up to 300 mm. The lack of the young of the year in the Gulf shore area during fall may support the view of Springer and Woodburn (1960), and others, concerning an offshore movement of the species in cooler weather. The black-phased individuals have always been seen as solitary fishes, except for the fol- lowing cases. The first was discovered by Dr. Clark and her daughter on Siesta Key during 1959 when the fish were most abundant. Then young black-phased Chaetodipterus were some- times seen in “clusters” of a few to about 20 individuals. These tended to be grouped either in contact with each other or very close to- gether, with tails toward each other. Each fish 5 It is to be noted that Chaetodipterus does not grow to as large a size in the Gulf of Mexico as it does on the Atlantic coast. Gunter (1945 and 1950) indicates and discusses this condition, having found no fishes over 195 mm after years of observation, while Hildebrand and Schroeder (1928) reported fish up to 12 lbs. in Chesapeake Bay. Nothing is known of the relative growth rates. Text-fig. 4. Distribution of small black phased Chaetodipterus at favored locations on the Gulf coast of Siesta Key, Florida, during the 1962 summer, one of unusually great abundance. S. L. indicates the southernmost city line of Sarasota. J. indicates jetty where much of the work was done. Water depth is as of mean low tide, in feet. Large circles along shore indicate concentrations of over 10 fish per square foot of bottom. Small circles indicate scattered individuals. See text for details. 1969] Breder: Aspects of Melanism in Acanthopterygian Fishes 113 faced outward in a different direction. They looked very much like a spray of dead and blackened weed and could easily escape notice.0 The fishes seemed to be just about at the size where hostility is replaced by schooling, and at the end of the black phase. These groups may be in a short-lived transitional state, which could account for them being so seldom seen. Another, but different case of non-solitary black Chaetodipterus was reported (Townsend, 1929) to have occurred in the New York Aquar- ium, when it was located at the Battery. A fully adult Chaetodipterus became uniformly black after being placed in an aquarium containing similarly sized Pomacanthus aureus (Bloch). When returned to the company of its own kind, it promptly took on the more usual banded phase. There has been no opportunity to check this further with other individuals, but it is in accord with present data and those of Breder and Rasquin ( 1955). Reid (1954) reported that, “When disturbed the fish darted among the barnacles; if the escape route was blocked they would remain motionless and could be caught easily by hand.” Evidently these fishes were in open water, above or beside the barnacle beds, which may account for the difference in behavior from those close to an open sandy beach. Other cases The following accounts cover species in which the black phase is only slightly known. Mycteroperca and Epinephelus These two genera of groupers, known for ex- tensive pattern changes, contain species which include in their repertoire of phases, one which is almost if not quite as black as those of the fishes previously discussed. Such black phases are mentioned and figured by Townsend (1929) for E. morio (Valenciennes) and striatus (Bloch) and for M. bortaci (Poey). The significance, if any, to the present studies is not clear. These fishes habitually change their patterns and col- ors, apparently more in reference to social be- havior than to background. Lobotes surinamensis Bloch The adults of this species are commonly very dark and often quite black. The New York Aquarium often obtained specimens from the “Dr. Clark also reported occasionally finding groups of these fishes that were remarkably similar to a spray of living sargassum weed in both general outline and coloration. This algae is not a very common floating element at this place, but there was some about at the time these fish groups were seen. lower New York Harbor, one of which is shown in Gudger (1931). The young display beautiful leaf mimicry and often aggregate with yellowed mangrove leaves (Breder, 1946 and 1949b). Platax orbicularis (Forskal) This species is often described as closely re- sembling yellowing leaves, in both form and color, e.g. Willey (1904), Mortensen (1917), and Randall and Randall (1960). The last de- scribed behavior rather resembles that of Chae- todipterus, but the color was not black. When seen in aquaria, in the United States, they are very apt to be solid black. Abudefduf taurus (Muller and Troschel) A single individual was seen in the black phase by Dr. T. N. Tavolga near the Marine- land Oceanarium, St. Augustine, Florida, in July 1952. His personal communication read, “It was placed in an aquarium, where it took two days for it to fade sufficiently for the normal pattern to become visible. The fish was about 15 mm s. 1." Tautoga onitis (Linnaeus) and Tautogalabrus adspersus (Walbaum) The young of these species are frequently found in a very black state from about New York Harbor northward. So far as known these all seem to be found in close association with notably black bottom materials, just as when found as bright green fishes associated with bright green plants, such as Ulva. Monacanthus sp. An individual of less than about 25 mm in length, in a coal black state, was seen near the surface amid some sea wrack, in Lemon Bay, Florida, in July 1967. It eluded capture by simply “disappearing.” Mortensen (1917) in- cludes this genus in those black forms he found floating in the sea amid blackened bits of wood. Stathmonotus hemphilli Bean This species is capable of considerable pattern change, although living cryptically for the most part. When in a nearly completely black phase, it will rest in the open on a light background, at least in an aquarium (Breder, 1949a). Histrio, Antennarius, and Ogcocephalus These genera are all capable of taking on a black phase (see Breder, 1949a and Breder and Campbell, 1958). The first two are definitely background-matchers and have not been found on a non-matching background, but the third is often seen in a completely black phase on light sandy bottoms. 114 Zoologica: New York Zoological Society [54:4 Table III. Pertinent Data on Chaetodipterus For each entry the collector or authority is given on the left side, following day and year. The numbers and total lengths in mm of specimens are given when known, unless otherwise indicated, under the reference name. The location and condition of the specimens is given at the right hand side. The tabulations are chronological by months. P. C. indicates “Personal communication.” APRIL 26/24 E. Clark (P. C.) Siesta Key, Florida 1 Small Black MAY 26/16 Hildebrand and Cable (1938) Beaufort, N. C. - - Females with advanced eggs 26/16 Hildebrand and Schroeder (1928) Crisfield, Md. — - Females with advanced eggs 3 1 /44 E. Clark (P. C.) Ft. Myers Beach, Fla. 1 24 s.l. Black 5/64 E. Clark (P. C.) Siesta Key, Fla. 6 — Black 13/64 E. Clark (P. C.) Siesta Key, Fla. Many Small Black JUNE Early Smith ( 1907 ) Beaufort, N. C. - - Ripe males and females 4/64 E. Clark (P. C.) Siesta Key, Fla. — Small Black 6/55 R. W. Harrington (P. C.) Indian River, Vero Beach, Fla. 3 20-30 Black 6/58 Springer and Woodburn (1960) Tampa Bay, Fla. 2 8.2-8. 5 1 1-13/42 Breder ( 1946) Pine Island Sound, Fla. 11 9± Black 14/60 Gunter and Ward ( 1961) Wine Island, La. 1 38± — 19-20/63 E. Clark (P. C.) Sarasota Pass, Fla. 3 Small Black 21/24 Breder ( 1946 ) Pine Island Sound, Fla. 1 - Ripe male 25/63 Kitty Paul Siesta Key, Fla. 5 11-25 Black -/48 Reid ( 1954 ) Cedar Key, Fla. 1 20 Black JULY 1/61 E. Clark Siesta Key, Fla. 50± 5.5-25 s.l. Black 3-5/42 Breder ( 1946) Pine Island Sound 2 9± Black 4/61 E. Clark Siesta Key, Fla. 69 6-24 s.l. Black. Great numbers seen 7/56 R. W. Harrington (P. C.) Indian River, Vero Beach Fla. 1 23 Black 9/58 Springer and Woodburn (1960) Tampa Bay, Fla. 3 19-25 — 9/29 Fowler (1931) Port Aransas, Texas 1 37 Banded 9/30 Hildebrand and Cable (1938) Beaufort, N. C. 1 9 Apparently black 9/64 S. Page Manasota Key, Fla. 2 Small Black 1969] Breder: Aspects of Melanism in Acanthopterygian Fishes 115 11/29 Hildebrand and Cable (1928) Beaufort, N. C. 1 2.5 Larval 12/15 Hildebrand and Cable (1938) Beaufort, N. C. 1 4.25 Apparently black 12/14 E. Clark (P. C.) Ft. Myers Beach, Fla. 1 25 s.l. Black 20/46 Breder (1948 ) Bimini, Bahamas Several Mature Black, countless banded 21/62 L. Godey (Records) Siesta Key, Fla. 8 1 8-32 s.l. Black -/49 Reid ( 1954 ) Ft. Myers Beach, Fla. - - Black -/ 48 Reid ( 1954) Cedar Key, Fla. 1 33.5 Black Mostly Gunter (1945) Bays & Gulf, Texas 6 & 7/41-42 44 62-195 - AUGUST 4/58 Springer and Woodburn (1960) Tampa Bay, Fla. 1 10 — 16/16 Hildebrand and Cable (1938) Beaufort, N. C. 1 17 Apparently black 23/30 Hildebrand and Cable : (1938) Beaufort, N. C. 10 49-62 Some barred, others probably black 25/43 E. Clark (P. C.) Ft. Myers Beach, Fla. 2 15-20 s.l. Black 25/56 E. Clark (P. C.) Manasota Key, Fla. 1 15 s.l. Black 29/57 E. Clark (P. C.) Siesta Key, Fla. 4 18-30 s.l. Black Late Smith ( 1907 ) Beaufort, N. C. - 73± - SEPTEMBER 3/58 Springer and Woodburn (1960) Tampa Bay, Fla. 1 10.1 - 4-6/30 Hildebrand and Cable (1938) Beaufort, N. C. 21 57-86 Some with bars, dark or light 18/55 Hildebrand and Schroeder ( 1928) Chesapeake Bay, Md. 1 55 - OCTOBER 2/22 Hildebrand and Schroeder (1928) Chesapeake Bay, Md. 8 69-83 — 3/58 Springer and Woodburn (1960) Tampa Bay, Fla. 1 16.8 — 3/24 Breder ( 1925 ) Sandy Hook Bay, N. J. 1 300± Banded 7/22 Hildebrand and Schroeder (1928) Chesapeake Bay, Md. 1 78 — 8/30 Breder (1931) Sandy Hook Bay, N. J. 1 457 - 1 1-13/22 Hildebrand and Schroeder (1928) Chesapeake Bay, Md. 2 80-100 18/21/30 Hildebrand and Cable (1938) Beaufort, N. C. - 72-74 Some banded, dark or li ight 18/61 Kay von Schmidt (P. C.) Siesta Key, Fla. 1 32 s.l. Black 23-23/15 Hildebrand and Schroeder (1928) Off mouth of Potomac River 12 65-85 _ -/48 Kilby ( 1955) Cedar Key, Fla. 1 20 — 760 Springer and McErlean Matacumbe Key, Fla. 4 19-31 1 16 Zoologica: New York Zoological Society [54:4 8/57 Field notes (original) NOVEMBER Pine Island Sound, Fla. Many 250± Bands strong -/60 Springer and McErlean (1962) Matacumbe Key, Fla. 11 32-45 - 3/43 DECEMBER Breder and Rasquin (1955) Bimini, Bahamas 1 76± Black -/ 48 Reid ( 1954 ) Cedar Key, Fla. 1 47 Black -/ 60 Springer and McErlean (1962) Matacumbe Key, Fla. 2 37-45 - Gymnochirus melas Nichols darkening of the lower portion. All fishes used The young of this species, up to about 50 mm, will rest on a light bottom under illumination and show a fully black phase. In darkness this species changes to a slightly lighter cross-barred pattern, but is still a very dark fish (Breder, 1955). The figure of a dark-conditioned fish of about 20 mm s. 1., with its bars showing, given by Breder (1955), agrees well with that of a preserved fish of about 31 mm given by Dawson (1964), who clarifies the relationships of this genus. were transferred to the basins directly from the traps in which they were caught. With these traps it was possible to do this without remov- ing the fishes from the water at any time. They have been described by Breder (1960 and 1962a). These experiments were carried out in 1960. Fishes Known to Have a Contrasting Black Phase. Trachinotus jalcatus Lepisosteus osseus (Linnaeus) A note from Dr. C. L. Hubbs, in Breder (1964), indicates that sometimes young indi- viduals of one to three cm, are found associated with decaying twigs and leaflets. These were a sooty black, which closely matched the litter. The above is the only case which possibly may belong to this group, which is not included in the Teleostei. It is, of course, a member of the Holostei, generally accepted as ancestral to the more modern Osteichthyes. Experimental Procedures Experiments were carried out in order to establish certain points not obtainable by simple field observations and to check earlier work. See Breder and Rasquin (1955) for experiments not repeated here. Plastic basins Conventional glass-sided aquaria are not satis- factory containers for the study of pigmentary changes under consideration here, because of the vertical black angles in each corner of the aquaria. Rectangular white polyethylene basins with rounded corners, measuring 14 Vi x 12 Vi x 5 Vi inches deep, were found to be completely satisfactory for these purposes. Since such con- tainers are slightly translucent they were kept on a clean white surface to avoid any possible Two individuals studied April 25 to 26. Each fish was placed in a separate basin. One basin held two pieces of black paper, a circular piece %o of an inch in diameter, and a larger, roughly rectangular piece. In the other basin were two circular pieces of paper identical to the circular piece in the first basin. The two fishes behaved in the typical fish manner, remaining substantially inert and seemingly indifferent to the approach of hand or net. A demonstration of their qui- escent manner is given in Plate 1, Figs. 1, 2, and 3. The first figure shows the normal undis- turbed fish, stationed some distance from the black marks. Here the distances are less than are usual in the sea; this fact may have some relationship to the size of the available swim- ming space or to the distance between the only black objects present. In the second figure a small net has been thrust under the fish. It can be noted that the fish is in a slightly different position than in the first picture. This was caused when the net accidentally touched the fish. Immediately, on the removal of the net, seen in the second figure, a hand was thrust into the water, as is shown in the third figure. The fingers wiggled continually, which the surface ripples indicate. The fish, between two of the fingers, retained its position throughout the dis- turbance. The behavior of the black fishes in the sea is indistinguishable from that here de- scribed in the basins. Similar sized fishes in a light and more or less background matching 1969] Breder: Aspects of Melanism in Acanthopterygian Fishes 117 phase dash about violently under identical treatment. Lagodon rhomboides Six light colored individuals were studied from March 16 to April 7. These showed at no time any suggestion of responding to any dark spots. The six fishes used were studied two at a time, each in a separate basin, so that each fish was always alone. Most of the time the fish rested in a more or less curved position, either in a very light phase or with a faint barred pattern. They always showed violent agitation on the slightest approach. It seems that here the chro- matic reactions are not especially linked to the background, but rather to their internal states in respect to fright or stress. There was some attempt at background matching but it obviously was not complete. The curved pose may be somewhat related to temperature for it was more in evidence when the water temperature fell to below 72° F. During this series of observations the temperature of the water ranged from 58° F to 82° F. Also in cold water the fishes stayed in the shadow of the rim of the basin whenever possible. This reaction is in accord with Barlow (1958) and Breder ( 1959), both of whom in- dicated that various fishes will become light- negative when water temperature lowers through some threshold value. The black example of Lagodon discussed in the preceding section, is the reason for including this species here. Fishes Not Known to Have a Contrasting Black Phase. Eucinostomus gala (Quoy and Gaimard) Nine fishes of about 15 mm were studied from Nov. 3 through 19. These were introduced into a basin as small fry, too young to be identified certainly in life. Recognizable characters devel- oped before this series was terminated and they were held further in an aquarium for confirma- tion. This was possible because a characteristic black tip develops on the dorsal, involving the membranes of the longest dorsal spines, entirely unlike any other small fish in this body of water. This becomes easily noticed by the time they are about 20 mm s. 1. During their sojourn in the basins they lived in a fairly close group and generally cruised about or rested quietly in a corner. At no time did they show any evidence of reacting to the dark spots. Throughout this period they maintained the lightest phase seen in this species and size, a little lighter than in fish taken over a clean sand beach. The develop- ment of the black dorsal tip is evidently inde- pendent of the background reactions of this species. Sciaenops ocellata (Linnaeus) Six fishes of about 28 mm s. 1. were observed from Nov. 10 to 18. When exposed to the en- vironment of the basins, this species responded in a way unlike any of the others to the black spots. Although they took on a very pale phase when placed in the light basin, typically they would rest their heads on a black spot. This act of placing the head on a black spot was imme- diately registered by the darkening of the me- lanophores, roughly in proportion to the amount of retina covered by the spot’s optical image — that is, it was related to the precise positioning of the head. If the head was not placed on the spot the darkening would be in approximate ratio to the nearness of the spot, if it were not more than about one-half inch distant. Fright would cause the fishes to leave the spots in haste, usually to “hide” on the side nearest the dis- turbance, where it was impossible for them to see the intruder. Both circular and rectangular spots were so utilized. Early in the morning these fishes were always lighter and usually not on their spots, but as day brightened they re- turned to them. Evidently they prowled about during the night, apparently in search of food. It would appear that intense light influences this species, at this size, to seek darker backgrounds. Symphurus plagiusa (Linnaeus) A single fish of about 22 mm s. 1. was ob- served from Nov. 11 through 18. This indi- vidual behaved as could be anticipated for prac- tically any flatfish, responding promptly to background and matching it as well as possible within the limits of its chromatic equipment. That is, in a white basin with no black spots it would all but disappear, except for its black pupils. Being still a very small fish at these times, it had the advantage of being virtually transparent. When a dark spot was present and in the fish’s visual field, the fish, darkened roughly in proportion to its distance from the spot, showing reactions similar to those de- scribed for Sciaenops. Variable light aquarium In order to have flexibility in the use of light for these studies, a special illuminating arrange- ment was provided. An aquarium constructed of clear sheet plexiglas, one-quarter inch thick, held together only by transparent cement, was employed. It lacked the dark corners of con- ventional aquaria, a needed feature for reasons already explained in connection with the plastic basins. The aquarium measured 18x12x12 inches, outside dimensions. It was placed on a table with a glass top measuring 24x151/2 118 Zoologica: New York Zoological Society [54:4 Text-fig. 5. Chaetodipterus. Presumptive growth curve based on data from various sources. The range between the two dotted horizontal lines shows the sizes at which the black individuals may be expected on the Atlantic and Gulf coasts. In the Bahamas the black phase may be found at much larger sizes. See Table III and text for full explanation. 1969] Breder: Aspects of Melanism in Accmthopterygian Fishes 119 inches. A light frame, supported by a single rod from each corner of the table, was constructed to hold whatever overhead illuminating fixtures or other equipment might be needed. Below the table a light-tight plywood enclosure, of in- verted pyramidal shape, was placed, with its base the glass table top and with a light socket at its apex, the low point, being near the floor. The plywood was lined with aluminum foil as a reflector and ventilated so that a small motor driven blower would prevent the aquarium from over-heating. Running sea water entered and left the aquarium by glass tubes, thus providing no dark spots within the view of the fishes. Translucent white paper was placed under the aquarium, on the glass table top, so that the under-lights presented a uniform illumination from below. A similar paper was placed under the overhead lights. The aquarium could be sur- rounded by any color of paper or cardboard called for. A further protection could be had by stretching sheets of paper or a cloth curtain between the four uprights supporting the over- head lights. It was thus possible to give the fish confined in the aquarium uniform illumination, either from above, below, or both, in any combination of intensity from none to the full amount the bulbs could deliver (a matter of 150 footcandles in the center of the aquarium from both direc- tions). Thus the overhead light alone, with its reflection from the bottom and sides would give a normal albedo, dependent only on the reflectivity of the surfaces and the clarity of the water. The added use of the underneath lights could provide “albedoes” greater than the bot- tom, of whatever nature, could reflect. It could be brought to, for instance, an impossible “al- bedo” of 1.0, or even beyond, by suitable manipulations. Much work has been done attempting to demonstrate that fishes in adjusting their pig- mentary systems are in fact responding to the albedo. See Walls (1942), Parker (1948), Odi- orne (1957) and Fingerman (1963) for reviews. This is the ratio of reflected light, R, to that of the incident light, I, from the bottom. Thus albedo = R/I, which is usually expressed as a decimal. The validity of this work on albedos is not universally accepted and, as it developed, it does not bear directly on present considera- tions. Through the use of this equipment how- ever, it became possible to delimit some of the parameters controlling the occurrence of the black-fish phenomenon, which follow. 1. Water sufficiently clear and shallow to permit good light penetration. 2. Illumination sufficient to make item 1 possible. 3. Location at or near primarily light bottoms or at the water surface,7 but not at intermedi- ate depths. 4. The presence of inert dark colored, typi- cally black objects of appropriate size, resting on the bottom or floating. Item 2, above, implies that in times of dark- ness the melanism should slowly lighten. The speed of this process is proportional to the original density of the melanophores. Item 3 is based on the fact that all observations have been made in these places. The reason for this is im- plied in item 4, as most submerged inert objects all either sink or float. Few are close enough to the density of water to have neutral buoyancy. As used here, the word “inert” does not imply lack of motion, for often slight wave action will move the lighter materials which rest on the bottom in a somewhat rhythmic manner. The floating materials are usually in motion with the surface waters. Tests of the operation of the variable-light aquarium were made with Oligoplites saurus (Bloch and Schneider), Gombusia afftnis (Baird and Girard), and Poecilia (Mollienesia) lati pinna (LeSueur). These fishes all behaved exactly as expected. The two poeciliids reacted in accord- ance with the studies of Sumner (1935) on Gambusia. Oligoplites, the young of which re- semble leaves (Breder, 1942), the only carangid so far studied in a variable-light aquarium, was not surprising in its reactions, but as the details of the reactions have no bearing on the present studies, they are not reported here. In no case did any of these fishes show any distress follow- ing full illumination from below for as long as a day. A sudden change in the illumination in- tensity would sometimes result in one or more of the fishes giving a slight momentary “start,” but nothing more. Chaetodipterus faber A single individual of 50 mm s. 1. was placed in the aquarium described above on August 31, 1967. This fish was in a thoroughly black state. :Mortensen (1917) considers the case of various small fishes swimming amid floating fragments of black- ened wood, which is clearly the closest mention in the earlier literature to the black fish problem, as under- stood here. Lepisosteus osseus, mentioned earlier, is evidently a fresh-water version of the same thing. Cott (1940) in his large treatise, essentially a catalogue of instances of alleged protective coloration, gives no ref- erence to anything equivalent to such cases. The present examples behave in a manner similar to his “Apose- matic” animals, exposing themselves freely and showing sluggish movements. 120 Zoologica: New York Zoological Society [54:4 It had been caught during some seining opera- tions of the Mote Marine Laboratory and be- fore being introduced into the experimental aquarium lived at the laboratory in a large tank with several kinds of larger fishes for about a week. It was not feasible to use more than one individual of this species at a time, as the smaller black-phased fishes usually fight violently, as has been noted by Breder (1946). The individual lived in the experimental aquarium until Octo- ber 2, when it was placed in a concrete outdoor tank, 9x6x3 feet deep, the interior of which was dark with various sessile growths. By this time the fish had attained a length of 54 mm. In the experimental aquarium this Chaeto- dipterus behaved in a manner consistent with the observations of Breder and Rasquin (1955), unlike the responses of the species used to check out the operational characteristics of the device. Table IV gives incident light intensity measure- ments of the light over the aquarium and its reflected values from the bottom. These include reflected values augmented by light under the aquarium to provide values sufficient to give “albedos” unobtainable by simple reflection. The readings showing the fish to be in a banded state are more numerous because when the fish oblit- erated its bars, by blackening the spaces between them and thus showing a solid black, that par- ticular observation was concluded. Text-fig. 6 shows this data in graphic form and indicates clearly that in all readings of under 300 f.c., the fish was banded and that there were no bars at values above 150 f.c. The pigmentary behavior in the area of transition was not de- finable precisely. It showed cases that were un- stable, the fish varying its pigment alternately, making an arbitrary “barred” or “black” desig- nation impossible. In the large concrete tank the fish maintained a barred phase, except for the following in- stances. By October 8, the fish had definitely taken up residence in a hollow cement building block which had been placed on its side and was well covered with dark growths. The fish ap- parently left this retreat only at feeding times, when the fish became decidedly darker, but did not completely obliterate the pattern of bars. The water ranged between 77° F and 74° F dur- ing this period. When the incoming water began to become decidedly turbid, owing to some nearby dredging operations, the fish no longer darkened at feed- ing times, but showed its strongest barred black- and-white pattern. Because of the turbidity, the water flow was turned off and the water cleared. This took about five days at the end of which time the water was crystal clear. The fish then showed a solid black pattern on emerging from its retreat and changed relatively slowly to a barred pattern. By comparison, the clarity of water before the turbidity occurred was only moderate. Under the conditions of the very clear water, when in the retreat, the fish could only see the very dark walls of the tank, which had not been visible to it during the period of turbid water. When the fish was returned to flowing water and a turbid condition, the black phase com- pletely disappeared. By this time (December 10) the water temperature had dropped to a range of from 12° F to 75° F. Also the days were becoming noticeably shorter and the sunlight weaker. At temperatures below 70° F, this spe- cies apparently cannot effectively concentrate the melanin granules. With water temperatures in the sixties, this fish remained darker than in the higher temperature range, but did not be- come completely black. The low light values evidently permitted a large loss of the many melanophores necessary to permit a black- phased fish. Discussion The presence of heavy black pigmentation is common to a considerable variety of acan- thopterygians, especially in the young stages, but reports of it occurring in other teleosts are nearly Table IV. Reactions of Chaetodipterus to Various Experimental Light Conditions Foot- Candles'1 Albedo State of fish 375 150 0.40 Black 7.5 2.7 0.36 Banded 30.2 30.2 1.002 Banded 150 150 1.002 Banded 300 150 0.50 Black 355 22.5 0.06 Black 6.0 1.1 0.18 Banded 4.5 0.9 0.20 Banded 2.5 4.5 0.20 Banded 03 0 0 Banded ’Upper figure = Light over aquarium. Lower fig- ure = Light under aquarium. 2 Impossible albedos produced by artificial means. See text for details. 3 Zero values at night, below threshold of F.C. meter. 1969] Breder: Aspec ts of Melanism in Acanthopterygian Fishes 121 all confined to black-phased individuals not found against a light background. Associated with this pigment density, as seen against a light background, are changes in the social atti- tudes, locomotor behavior, and avoidance re- actions. Since this study is confined to nearly uni- formly black fishes, found on light backgrounds in very characteristic solitary and sedentary states, the following comments are given here to avoid possible confusion. Various dark col- ored fishes not considered here have been ex- cluded for a variety of reasons. These, though apparently few in number, may be illustrated by the following case. Melichthys radula (Solander) as seen in the sea is a nearly black fish which occurs in aggre- gations, schools, or as solitary individuals, and is a remarkably fast swimmer for its type, being comparable with the generally gray Canthider- mis sufflamen (Mitchill), with which it is sym- patric. The former, although superficially sug- gestive of the fishes under consideration, has the following distinguishing characteristics. Al- though very dark, almost black, there is a bril- liant iridescent blue and very narrow line running along the bases of the dorsal and anal fins. There is little pigmentary change in these fishes, but there is a tendency toward yellowish color in their dark sides. This is most pro- nounced in old aquarium inmates that are not in full health, when the striking blue line fades to whitish. It is doubtful that this species has much color matching ability, which lack is char- acteristic of the adults of the Balistidae as a whole. However many of the species — espe- cially those that stay close to coral growths — have very gaudy markings of bright colors. That tendency is of course present in most groups of fishes with representatives in such areas. Environmental circumstances Fishes with a normal melanism are charac- teristically found either against a black or nearly black background or against a light and strongly contrasting background. The first, which repre- sents the classic matching response is by far the most frequently seen. The first may be shown at practically any size, but the second, so far as known, is mostly limited to the very young or at least the not fully mature fishes. Both back- ground matching and background contrasting fishes can attain almost complete visual oblitera- tion, and for very different reasons. Thus the physical appearance of the background must be of a fairly definite kind in order to enable either of the above pigmentary types to attain any con- siderable degree of inconspicuousness. The pattern of backgrounds Natural backgrounds usually partake of con- siderable randomness. At this point, however, a consideration of formal geometrical back- ground patterns may be more useful. Obviously at opposite extremes, one could have a pure white and a solid black background. A series of graded gray fields could bridge the two ex- tremes, in as small steps as required. However, all these fields are unlike most natural back- grounds. The grains of pigment making up the lightest gray to the black fields could be en- larged to any size, so that some of the inter- mediate fields would show polka dot patterns. These could be constructed as black dots on white, or vice versa. Such a pattern of black dots would end in solid black simply by increas- ing the number of dots per given area. The size of the dots used would determine how fast the fields converged to solid black. It is obvious that some of the intermediate fields would begin to take on a resemblance to light sandy shores with various amounts of dark debris scat- tered about. Also, it is clear that a stray spot of appropriate size could easily “get lost” on such a field, and even more easily if the backgrounds were randomly distributed instead of being ar- ranged in a precise pattern, and especially so if they were not all perfect circles. Recent studies by Donderi (1966) on the disappearance of identical or similar objects of simplified visual stimulus against a plain background give addi- tional reasons for the effectiveness of this gen- eral means of visibility reduction. Of course, in a natural state, a light colored fish on a light field or a dark fish on a dark field has its visibility greatly reduced. It is in these areas that the adjustable chromatophores evi- dently operate. It is noteworthy in this connec- tion that many fishes, in or out of a school, are very reluctant to move over a dark patch when in a light phase and vice versa. In clear water it is easy to see such fishes winding their way over a mottled bottom in accordance with this reluctance (Breder and Rasquin, 1951). Natural sea floors often present a pattern of rather random uniformity for considerable stretches. That is, a fine sand bottom may be considered as a degenerate form of pattern and a smooth unpatterned surface. If the grain par- ticles are increased in size, a coarser pattern develops. It passes through large gravel to boulders and reaches a point where a single large rock covers the area of observation. This, if uniform itself, is again a degenerate pattern. However if this rock has texture, it can be con- sidered in another series. Usually in nature the situation is not so simple but more likely to be 122 Zoologica: New York Zoological Society [54:4 Text-fig. 6. Chaetodipterus. Relationship of pig- mentation of a single fish to incident and reflected light intensity in foot candles. Black circles indicate the black phase. Light circles indicate the banded phase. Three values for the banded phase, crowded near the origin, are not shown. Based on data of Table IV. See text for full explanation. a mixed background of two or more separate series in which one, at least, is a near-degenerate pattern and at least one of the others, a rather coarse pattern. Such a case would be a sea floor of fine sand on which rocks of a limited size range are scattered and on which may be a patterning of a limited variety of sea growths. This type of combination of a degenerate back- ground of virtually no pattern combined with a scattering of discrete larger objects is the type in which the black fish phenomenon is most likely to be found. Naturally the discrete ob- jects need not be rocks, but may be anything that locomotion or wave action may distribute in a scattered pattern. Obviously the manner in which these items are scattered insures a cer- tain amount of regularity in both size and shape. This applies to such things as mollusks, sponges, dead leaves, or whatever happens to be com- mon in the locality. Given a fish of a certain size with reference to the texture of such a background, it is evi- dent that there is an opportunity for a variety of concealing responses, each with its accom- panying appropriate behavior. Thus, some fishes match the light sand and avoid the coarse and contrasting darker objects, while others take on darker colors and avoid the light sand background. Also, those that are the subject of this paper, which have darker colors, remain nearly stationary on the light background and become, in effect, just other random objects. At this point the question of whether a fish matches or contrasts with its background begins to break down and it is seen that one cannot clearly say which is which, however convenient it is to think of light-and-dark-phased fishes in such terms. What can be said, however, is that the light fish has only one way to become in- conspicuous; that is to keep in the light phase most nearly matching the sand, whether it is active or stationary, whereas the dark fish has, in theory at least, two choices. These are, of course, settling on the dark objects or settling away from them, but in the latter case remain- ing relatively quiescent and avoiding associa- tion with others and the attending activity and conspicuousness a group entails.3 If the question is raised as to why the light colored fish cannot inversely “get lost” on a large dark area with light spots, the answer seems to be that such cases have not been found. Probably the real reason might well be associated with the fact that dark sandy beaches strewn with light col- ored objects are not easily found. Even if these do occur, they would seem to be altogether too uncommon to make it likely for fishes to adapt to a thing of such limited utility. It is as yet impossible to say just why these dark fishes usually station themselves about equi- distant between dark objects and much less fre- quently, rest relatively near them. Were it not for this, it would be tempting to imagine that they distribute themselves randomly with respect to the scattering of objects. This would be as much as saying that the fishes are reacting to the randomness of the field, which could not be as effective as if they spaced themselves definitely in respect to the objects in their immediate area, as they evidently do. The above remarks rest on the idea of spe- cific approach or withdrawal by a fish toward or away from some feature of the bottom or some floating object. Pigmentation adjustment is also a matter of the approach-withdrawal scheme, but on another level, that of the melanin granules within the melanophores, toward or away from each other. In turn these granules invoke accordingly the pale or the dark phase. Therefore, these matters could be considered in the terms used by Schneirla (1959) in the most recent and broadest exposition of his theory of biphasic processes. The influence of turbidity Only in very clear water, or in water so shal- low that a slight turbidity does not matter, are 8 Those dark fish which form groups under such con- ditions are either highly motile or mimic some objects in the environment, so far as known. 1969] Breder: Aspects of Melanism in Acanthopterygian Fishes 123 such fishes with contrary pigmentation to be found. One way to change such pigmentation is to turbidify the water (Breder and Rasquin, 1955). Sometimes one may find that fishes in a light phase and those in a black phase are living in a common area. Breder (1946) reported that Chaetodipterus in the black phase was found in two inches or less of water and slightly larger ones, in schools of light phased (banded) fishes, nearby in a foot or more, where the water was sufficiently deep to provide an appreciable turbidity. Lagodon is reported performing in a similar manner herein. Temperature and pressure In general, organisms with melanophores dis- perse the granules within them under the influ- ence of relatively low temperatures and con- centrate the granules under high temperatures. This is also true of relative pressures and there- fore depths of water over organisms. There are some complications to this general statement, involving various species, including some tele- osts, as Parker (1948) and Fingerman (1963) have indicated. It has been argued and in some cases demon- strated with other material that this melanophore activity is thermoregulatory. It is true that dark objects under illumination become heated more than do white ones in identical conditions, but only if not submerged. Because of the heat ca- pacity of water this is not true in aquatic en- vironments, as has been pointed out by Bauer (1941). Moreover even if the above were not true, this situation could hardly function as a thermoregulator as it is “aimed” in the wrong direction to benefit the fishes discussed here, which are not far from their upper thermal limits. What other function such a black invest- ment could have, except as a protection against over-exposure to radiation, is not evident.0 While it is true that the phenomenon does not occur in turbid water, it also happens that the species considered have a good development of guanine deposits. Other species without the black cover- ing live in the same environment. They have 9 It is noted that the black investment of abyssal fishes is at the opposite end of the series, being associ- ated with very cold water and the absence of solar radiation. Also at these depths the pressures verge on those inhibiting the concentration of melantin granules, at least of the type possessed by some shallow water species, Marsland (1940, 1942a, and 1942b). Also from the preceding reasons alone, it is doubtful that the dis- cussion between Cowles (1967) and Hamilton and Heppner (1967) could have any direct bearing on the present problem, especially as their work involves only homiothermal terrestrial forms. elaborate patterns of many sorts or are simply silvery or partly transparent. (See Breder, 1962b, for a discussion of the role of transparency, guanine, and pigment in the mostly transparent planktonic fish eggs and larvae.) Influences encouraging melanism It has been demonstrated that a distinct dark phase can be induced experimentally by a number of diverse stimuli and that local dark- ening can also be induced by suitable local treat- ment. Extensive references and details may be found in Parker (1948). Other pertinent refer- ences follow: Chavin (1956 and 1959), Egami et al. ( 1962), Ellenger ( 1939 and 1940), Finger- man (1927 and 1930), Fukui (1927 and 1930), Hu and Chavin (1956), Kosto et al (1959), Muzlera (1934), Osterhage (1932), Rasquin (1946 and 1958), Smith, D. C. (1928), and Smith, G. M. (1931, 1932a, and 1932b). General All-Over Darkening. 1. Internal and external applications of vari- ous hormonal and chemical agents, including intermedin, prolactin, MSH, acetylcholine, cu- rare, yohimbine, ethyl alcohol, novocaine, and sodium chloride. 2. Blinding, as by nerve section or opaque eye covers, in the presence of light. 3. Exhaustion from stress, as in an “Omega” fish. 4. Exposure to chill. 5. Exposure to a very dark background. Localized Darkening. 6. Local applications of hormonal and chemi- cal agents, as listed under item 1. 7. Trauma involving cut cutaneous nerves and severed capillaries, with darkening appear- ing posterior to the cut. 8. Trauma from radiation with X-rays and cautery, with the darkening variously localized. This list indicates that, in all but item 5, defi- nitely traumatic or stressful situations are in- volved. It is not to be inferred that all these methods produce as intense a melanization as may item 5. In fact there is only one method known that will regularly produce a darkening equivalent to that induced by background. This method, item 2, simply eliminates the sense by which the nervous control of melanophores is mediated. Since the fishes of item 5 are obvi- ously not blind, showing normal responses to purely optical stimuli, the importance of the controlling role of vision in their observed reac- tions is clearly demonstrated. Two types of activity take place in the case of a fish going into a darker phase. The first is 124 Zoologica: New York Zoological Society [54:4 the dispersion of granules of melanin in the existing melanophores, the so-called physio- logical changes. This can happen in minutes or seconds and darkens the fish in proportion to the number of integumentary melanophores present. The extent of the darkening by this means varies with both the species and the individual involved and its recent past history. The second type of darkening is brought about by the development of more melanophores, a process that may run into weeks for comple- tion, the so-called morphological changes. It is, of course, the presence of vast numbers of melanophores that alone can produce the in- tense blackening considered here. Fishes return- ing to a lighter phase can at first only lighten their blackness to the extent that the remaining numbers of melanophores will permit. This may not even be noticeable, if their number is so great that even with the greatest concentration of melanin granules, no paler fish results. There- fore the ability to show a changeable pattern likewise must await a reduction of melanophores to a sufficiently low level, which too can take weeks. Physiological circumstances Fishes with a sufficiently dense investment of melanophores to be referred to as melanistic are very striking objects when seen against other than a black background or a mottled one of very specific characteristics. These mottlings must bear a relationship to the size of the fish in such a manner that the fish becomes effec- tively a part of the pattern. One of the most striking features of these fishes is their complete lack of countershading, which is a feature of most non-melanistic fishes and which is impor- tant to their ability to become inconspicuous. Vision and pigment Most small fishes are not known to produce an intense darkening, even if kept for a long time on a dark background, although in time they reach a dark stage which is evidently as far as they are able to go in this direction. How- ever, this falls far short of the extremes seen in the special cases considered here. When such fishes are placed on a light background they simply revert to an appropriately light phase, apparently as rapidly as their physiological proc- esses will permit. The case of response to a dark spot which has been discussed earlier in- dicates merely that the reactions differ from those of the black fish in various details. The case of Gambusia in passing from a dark environment to a light one, by natural means (described by Breder, 1947), appears pertinent in this connection. While the fishes immediately hide under a leaf or similar shelter until they have become sufficiently lightened, there is no evidence of posturing nor need for such be- havior under a leaf. In cases where no leaves or other shelters are present, they merely “hug” the walls, as do background-matching fishes when first introduced into a new environment. All this does indicate, however, that fishes on a “wrong” background ordinarily make suitable adjustments in their behavior. The adjustments presumably have considerable protective value. Breder and Rasquin (1951) reported that Cyprinodon in a white bucket would hesitate to leave it if lowered into a dark-walled tank. If forced out into such a tank and if it contained larger predatory fishes, the Cyprinodon would immediately return to the bucket, but in the absence of the predators, they would instead immediately hide as well as they could in the new non-matching surroundings. The only chromatophores found in the integu- ment of Chaetodipterus are melanophores and a much smaller number of xanthophores. Asso- ciated with these pigment bearing cells is a large number of guanine containing cells. Of these the iridophores are numerous and many occur in association with melanophores in the form melaniridosomes. Otherwise there is enough to account for the silvery sheen of these fishes when in their lightest phase. No leucophores were seen, but it is more than likely that a few may be present or developable by the evoca- tion of a suitable background presented for a long time. This species is thus limited to pat- terns of black, white, browns, and yellows in various combinations. Meek and Hildebrand (1925) described young Chaetodipterus as re- sembling dead leaves. A considerable number of fishes have been noted to bear more than a passing resemblance to leaves, a subject most recently reviewed by Randall and Randall (1960). This type of mimicry is closely related to that of the melanistic fishes here under discussion. It might be argued that one could be the precursor of the other, but the order of se- quence is not clear. Randall and Randall in- clude Trachinotus falcatus and Lobotes surina- mensis in their list of apparent leaf mimics. The adult of the latter species is often very dark or solid black and is commonly found solitary, drifting in the open sea accompanying a log or other object (see Breder, 1949b). Except for Platax, other species of young fish resembling leaves are not known to have black adults. Circadian rhythms Apparently no studies have been made to attempt to separate the effects of the absence 1969] Breder: Aspects of Melanism in Acanthopterygian Fishes 125 of light on teleosts from a possible diurnal rhythm which may exist, at least for a time, under constant darkness or illumination. Many teleosts alter their patterns in darkness, usually by concentrating the granules in the melano- phores or other pigment cells, e.g., Holocentrus, a genus of mostly reddish fishes, which at night are blanched to almost complete whiteness. Young (1935) described a daily color rhythm in which the cyclostome, Lampetra, becomes pale during the night and darkens during the day. He found it responsive to light, but also found a daily rhythm which in some individuals continued for many days when kept in dark- ness, but for a shorter time than in an alternat- ing cycle of light and darkness. It would be instructive to determine how much of the effect is owed to the direct action of light and how much is endogenous. It may be assumed that various groups of fishes would differ widely in this respect. Internal secretions In the literature on the control of chromato- phores and color changes, there is little about contrasting pigmentation and where it is men- tioned it is usually treated as an unexplained oddity. (See, for example, Parker, 1948, and Fingerman, 1963.) Enami (1940) found that Parasilurus asotus (Linnaeus) darkened on the injection of epi- nephrin. This is contrary to epinephrin’s effects on most other teleosts, but similar to what Breder and Rasquin (1950 and 1955) reported for Cliaetodipterus faber. They noted that under the influence of this hormone the integuentary melanophores dispersed their granules. How- ever, unlike the effect reported by Enami (1940), the iral and meningeal melanophores, which are part of the epinural system, concentrated their granules. The fishes described here dif- fered from these injected fishes in that the irises were always found to be as black as the rest of the body.10 Although it is true that individual species of vertebrates and invertebrates show differing pigmentary reactions to various hormones, there appears to be no reason to suppose that back- ground-contrasting pigmentation has its genesis in peculiarities of the endocrine system, but rather that it is based primarily on the activities of the nervous system under special environ- mental situations. 111 The only known exception to this is that of Trachi- notus falcatus, in which examples in the black phase may have red irises. Comparison with melanotic conditions Many fishes have intensely black marks, which are made up of massed assemblages of melanophores, as part of their general pattern. Others show characteristically irregular black marks, which seem to be more or less randomly distributed and may vary widely in number from one individual to another, as in the Sphyraena barracuda (Waldbaum) and certain genera of poecilids, Poecilia (Moliienesia), Gambusia, and Xiphophorus (including Platypoecilus) . There seems to be no reason to suppose that these are all necessarily precursors to melanomas. How- ever it has been shown, by purely genetic means, that in the case of Xiphophorus they could de- velop into exceedingly virulent melanomas (see, for instance, Gordon, 1948 and 1957). In addition to the above malignant conditions, a persistent background-developed melanism may be the causative agent in other pathological conditions. Sumner and Douderoff (1938) de- scribed an apparently infectious condition asso- ciated with lesions and emaciation which oc- curred in 36% of Gambusia kept in black bowls as against 2.5% in white bowls. Thus it would appear that fishes living in a state of continual melanism might be confronted with health prob- lems of a magnitude they would not encounter in an environment incapable of inducing such intense pigmentation. It would seem possible that this circumstance would tend to cause at least some fishes to accept a heavy melanism and therefore a very dark background only as a transient phenomenon. There appear to be at least three means by which integumentary melanophores can be eliminated by teleosts. Of these one is described by Osborn (1941), in which the degenerating cells and their contents are expelled through the epidermis into the surface mucus and finally washed away. The second is the sloughing off of whole heavily melanistic areas,11 a process which has been described in detail for Tylosurus raphidoma (Ranzani) by Breder and Rasquin (1952). Other synentognaths use a third way: Tylosurus acus (Lacepede) and two flying fishes of the genus Cypselurus simply resorb such areas in situ (Breder and Rasquin, 1954). Evidently in the last means of eliminating melanophores and their granules, only phagocytosis is in- volved. While it is possible that there is also some phagocytic activity present in the other “It should be noted in this case that the black area sloughed off is the posterior lobe of the immature dorsal fin and it is accomplished with no evidence of phago- cytosis. The black mandibulary lappet of this fish is eliminated slightly earlier by simple resorption. 126 Zoologica: New York Zoological Society [54:4 two, it is not yet established and may be slight or absent. Breder and Rasquin (1952) considered the appearance of the sloughing dorsal lobe of Tylo- surus raphidoma similar to the second stage of melanosis in Xiphophorus, as described by Reed and Gordon (1931). Whether such overex- tended tissues should be considered benign or simply self-limiting has been discussed by Breder (1952). The latter could conceivably be brought about because of some resulting structural weakness. Survival values The contents of the preceding pages suggest that the apparently inverse reactions to light backgrounds can come about only under spe- cial and somewhat unusual conditions and that it is possible only in a rather limited variety of fishes. It would appear that fishes which have already abandoned general direct tonal response to a generalized background in favor of colors and general appearances of leaves might take a further step. The further step, that of black- ening and appropriately distributing themselves, brings them to the condition discussed here. They have attained an approach to various more generalized but individuated items to which they bear a somewhat general resemblance. There is however no precise matching, such as they may have originally had to leaves of specific plants or trees, but the results must still be of suffi- cient survival value to be maintained, even if only for certain definite periods in life history. As earlier suggested it seems to be equally possible that a general blackening provided some early survival value which then went on to a very detailed matching of leaves of a single plant species. There is still insufficient data on this to warrant further speculation on which process would seem the more likely. It might even be that some fishes evolved in one of the above manners while others evolved in the alternate. The melanophore system of many fishes re- acts to the intensity of light by dispersing the melanin granules and to the tone of the back- ground by modulating this behavior, with the result that the fishes approximate a tone similar to that of the background. These two activities have been referred to as the “primary response” for the first and as the “secondary response” for the second. They appear in that order in ontogeny (Parker, 1948). These features of chromatic adjustment are regulated jointly by the endocrine and nervous systems. The endo- crine system is in general responsible for the dispersion of the granules and the resulting darkening of the fish, while the nervous system is similarly responsible for the concentration of granules and the lightening of the fish.12 It is the operation of these systems in certain fishes, in shallow strongly illuminated waters, that leads rather unexpectedly to melanization of marked intensity. Similar-appearing melani- zation is also to be found under the great hydro- static pressures found in ocean depths. Other- wise the two systems, hormonal and neural, permit the showing of colors and patterns dif- ficult to distinguish from the background. Were it not for the nervous control, mediated through the eyes, fishes would be expected to show their darkest phase under intense light, irrespective of background. From the preceding it follows that a fish which had been reacting normally to a light background could hardly be expected to change the direction of its pigmentary responses. There appears to be no environmental situation nor physiological condition, in normal feral fishes that could bring this change about. Therefore one is left with the alternative that these fishes in the black phase must have initially adjusted the melanophore system to a very dark or black background. It is possible to establish several observable conditions which suggest just such a genesis of the melanism under study, as follows. 1 . Fishes in such a black state are frequently found amid drifting fragments of wood that have been charred or otherwise blackened, and are either floating at the surface or water-logged and resting lightly on the bottom.13 All the fishes showing melanism against a light background discussed here hatch from pelagic eggs and spend their larval and sometimes post-larval life as plankton. Therefore such association with small black objects is not especially unusual. In the planktonic environment of the open sea, there is little else to which a chromatically active young fish, with perhaps only melanophores as yet developed, could react. At the place where small black Chaetodipterus are most abundant (Text-fig. 4), huge quantities of charred wood fragments often are caught up and swirled about by the same currents which evidently concen- trate the black fishes at that place. As these 13 It is recognized that this is somewhat of an over- simplification, that pigment control is a very complex matter, and that all fishes do not respond in identical fashion. See Odiorne (1957) for a brief summary of these complexities. 13 Incidentally there are many more bits of blackened wood floating in the sea than is generally supposed. These bits are naturally most abundant over the con- tinental shelves. They are delivered to the sea primarily by rivers and secondarily by high winds accompanying forest fires or other fires of large magnitude. This mate- rial is almost always a uniform dull black and remains buoyant for a long time. 1969] Breder: Aspects of Melanism in Acanthopterygian Fishes 127 larvae develop and drift into shallow water they drop out of their planktonic stage and take up a more or less littoral bottom life leading to adulthood. 2. If the small fishes are not blackened by means mentioned in item 1, there is added pos- sibility that the young fish on abandoning pelagic life may encounter a sea bottom, or more likely a bay bottom, which is black or at least very dark. Such are not uncommon on the North American Atlantic and Gulf shores. These black items and black-bottom bays are very common where the Chaetodipterus studies were under- taken. 3. Whether the black-phased fishes come out of this condition rapidly or very slowly, on en- countering a light bottom, is obviously primarily controlled by the density of the melanophores. If the fish has been on a dark background long enough to produce the maximum quantity pos- sible, it may take as long as three weeks for the fish to lighten noticeably. If it had lived on the black background only the minimum time neces- sary to prevent it from showing a prompt “physi- ological” change to a lighter and patterned appearance, a sufficient reduction of the melan- ism to permit such changes would take much less time. A similar appearance would be ap- parent to the observer, depending on how long ago the fish had left the black background. That this is not a matter of habituation and a reluctance to change from a quiescent and solitary attitude to an active and social one is indicated by the prompt return to the latter when the pigment has sufficiently lightened. Further elucidation at this time of the relation- ship between pigment control and social beha- vior, both of which are chiefly mediated through the eyes in these fishes, would probably have to involve a very difficult differentiation of the pre- cise neural pathways of both actions. A problem related to the above and to several of the preceding items involves a question of what, if any, influence the early development of abundant melanophores has on subsequent pig- ment behavior. It is conceivable that such early darkening might induce a bias toward its reten- tion, which could suggest some form of habitua- tion. There is, as yet, no evidence indicative of this, but the presence of such a bias could be readily masked. The thought cannot be sum- marily dismissed. In three genera the sizes at the onset of heavy melanism are known. None of these genera, Trachinotus, Menticirrhus, and Chaetodipterus , have young which are readily obtained alive or easily maintained under labora- tory conditions. Because of this an early solution of the question would seem unlikely. The preceding three items are all that are necessary to give a plausible explanation of what first appears to be a reverse reaction to the background. The only item that the above does not cover is that of the locomotor behavior and posturing. This is clearly related, however, to the attitudes of other fishes when confronted with a background to which they contrast in- stead of approximate. On this basis then, the implications to pro- tective behavior and survival would seem to be clear. The action of the fish thus becomes one of matching the background if possible, but if not, of freezing and arranging itself against a mostly contrasting background as inconspicu- ously as possible. This action permits time for the slow acting “morphological” adjustments to be made. Ancillary observations indicate that the black fish phenomenon is a very late spring and sum- mer matter, reaching its full development in July and August and disappearing rather rapidly in the fall, at least in the area in which these studies were made. This is probably no coin- cidence, for the young of the year of the species involved are present and the long days of sum- mer illuminate the environment at maximum. The length of day may be even more influential than the greater intensity of light at this season. It should be noted that in all these black fishes, the normally lighter under parts, the ordinary “counter shading,” of fishes matching any but fully black backgrounds, is absent. The ventral areas are as black as the dorsal areas. This con- dition of melanism in any other than a very dark environment would make the fishes very conspicuous. For the validity of counter shad- ing as a protective mechanism, see Cott (1940). If the various fishes which show a distinctly black phase against a light background are con- sidered from a phylogenetic standpoint, some suggestive relationships appear. It is still too soon, however, to be certain of the significance of these relationships. A list of the groups in- volved is shown in Table V. It is based on the most recent phylogenetic scheme for teleosts, which has been proposed by Greenwood et al. (1966), and is here followed throughout this discussion. The table shows that the phenome- non is confined to what these authors designate as Division III. Within this all are encompassed by two sub-orders, Acanthopterygii and Para- canthopterygii. The single remaining order, Protacanthopterygii, thus far is without such representatives. Those species that have been observed rest- ing on a light background, in a black phase, 128 Zoologica: New York Zoological Society [54:4 posed in a more or less coiled position, and lacking the tendency toward hasty departure on approach, represent eight genera as shown in Table V. The other nine genera in which the possibility of the typical black fish reactions seem likely have not been under close observa- tion. These are also indicated in this table. Taken together, the data in Table V indicates that this condition is most strongly represented in the Percoidei, with five and six genera respectively. In the Paracanthopterygii, there are three genera all of which are in the Antennarioidei. The single non-teleost which has been mentioned is the Holostean, Lepisosteus. It thus seems likely that this natural melanism may be found to be confined to this single but broad band of phylogeny. Summary 1 . Fishes are discussed which display an al- most complete melanism against a light background and which are consequently strongly contrasted to it. 2. The locomotion and social attitudes of these dark fishes are unlike those of indi- viduals of the same species not in the black phase, as the latter aggregate or school and escape capture by fleeing, whereas the black individuals are solitary, quiescent, and agonistic and freeze on approach, usually in a characteristic twisted pose. 3. This phenomenon, so far as known, is con- fined to young acanthopterygian fishes of the families Carangidae, Sparidae, Sciae- nidae, and Ephippidae, although there are suggestions of it in other families of tele- osts and one holostean. 4. It has only been found in warm water dur- ing the warm half of the year. 5. The species best known to display melanism in this manner are Trachinotus fcilcatus ( L. ) , Lagodon rhomboides (L.), Menti- cirrhus 4 sp., and Chaetodipterus faber ( Br. ) , with over fifteen other cases, in- volving species about which there is some uncertainty. 6. The apparent conspicuousness of the black phase, on a light background, is mitigated to a very great extent by the usual scatter- ing of small dark objects, such as tiny shells and bits of decaying plants. 7. This item and all following are interpreta- tions, based on field observations and ex- periments. The black phase must appear initially from exposure to a dark back- ground, because of the manner in which the neuro-endocrine controls operate. 8. Prompt “physiological” response to dis- placement to a light background in a bright light is usually impossible because of the intense melanization which requires the slower “morphological” loss of melano- phores before the change can become apparent. 9. The length of time a fish retains this melanic condition is dependent on how long it has resided on a dark background and how recently it has left it. Table V. Phyletic Occurrences of “Black-fish” by Genus and Higher Taxa. Bold face; definite, by observation. Italics; possible or probable, by inference. Paracanthopterygii Lophiiformes Antennariidei Antennariidae Histrio 1 1 Antennarius 1 1 Ogcocephalidae Ogcocephalus l1 Acanthopterygii Perciformes Percoidei Serranidae Epinephelus l1 Mycteroperca 1 1 Carangidae Trachinotus 1 Lobotidae Lobotes 1 Sparidae Lagodon 1 Sciaenidae Menticirrhus 14 Ephippidae Chaetodipterus 1 Platax 1 Pomacentridae Abudefduf 1 Labroidei Labridae Tautoga 1 Tautogalabrus 1 Blennioidei Clinidae Stathmonotus 1 Pleuronectiformes Soleoidei Soleidae Gymnochirus 1 Tetraodontiformes Balistoidei Balistidae 1 1 Monacanthus 1 This genus does or may contain more than one species subject to the “black-fish” phenomenon. 1969] Brecler: Aspects of Melanism in Acanthopterygian Fishes 129 10. The size at which fishes outgrow this type of reaction appears to be related to light intensity as modified by water turbidity. 11. The entire phenomenon may be almost entirely on the ontogenetic level, but ap- parently in certain cases some is on the phylogenetic level, at least in Chaetodip- terus faber. Bibliography Baird, S. F. 1873. List of fishes collected at Woods Hole. Rept. U. S. Fish Comm. 1871-72, pp. 823- 827. Barlow, G. W. 1958. Daily movements of desert pupfish, Cypri- nodon macularius, in shore pools of the Salton Sea, California. Ecology, 39(4): 580-587. Bauer, V. 1914. Zur Hypothese der physikalischen Warme- regulierung durch Chromatophoren. Zeit. Allg. Physiol., 16: 191-212. Bean, T. H. 1888. Report on the fishes observed in Great Egg Harbor Bay, N. J. for 1887. Bull. U. S. Fish Comm., 7: 129-154. Beebe, W., and J. Tee-Van 1928. The fishes of Port-au-Prince Bay, Haiti. Zoologica, 10(1): 1-279. Breder, C. M„ Jr. 1923. Certain fishes from Sandy Hook Bay. Copeia (114): 2-3. 1925. Fish notes for 1924 from Sandy Hook Bay. Ibid. (138): 1-4. 1926. Fish notes for 1925 from Sandy Hook Bay. Ibid. 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The problem of directives to cellular pro- liferations as illustrated by ontogenetic processes in certain fishes. Growth, 16: 189-198. 1955. Special features of visibility reduction in flatfishes. Zoologica, 40(8): 393-482. 1959. Studies on social groupings in fishes. Bull. Amer. Mus. Nat. Hist., 1 17(6): 393-482. 1960. Design for a fry trap. Zoologica, 45(10): 155-160. 1962a. Effects of a hurricane on the small fishes of a shallow bay. Copeia (2): 459-462. 1962b. On the significance of transparency in osteichthid fish eggs and larvae. Ibid. (3): 561-567. Breder, C. M., Jr., and M. L. Campbell 1958. The influence of environment on the pig- mentation of Histrio histrio (Linnaeus). Zoologica, 43 ( 12) : 135-144. Breder, C. M., Jr., and P. Rasquin 1947. Comparative studies on the light sensi- tivity of blind characins from a series of Mexican caves. Bull. Amer. Mus. Nat. Hist., 89(5): 319-352. 1950. A preliminary report on the role of the pineal organ in the control of pigment cells and light reactions in recent teleost fishes. Science, 11 1(2871): 10-12. 1951. A further note on protective behavior in fishes in reference to background. Copeia (1): 95-96. 1952. The sloughing of the melanic area of the dorsal fin, an ontogenetic process in Tylosurus raphidoma. Bull. Amer. Mus. Nat. Hist., 99(1): 1-24. 1954. The nature of the post-larval transforma- tion in Tylosurus acus (Lacepede). Zoo- logica, 39(3): 17-30. 1955. Further notes on the pigmentary behavior of Chaetodipterus in reference to back- ground and water transparency. Ibid. 40(7): 85-90. Chavin, W. 1956. Pituitary-adrenal control of melanization in xanthic goldfish, Carassius auratus L. Journ. Exp. Zool., 133(1): 1-46. 1959. Pituitary hormones in melanogenesis. In Pigment Cell Biology. M. Gordon [Ed.], Academic Press, N. Y.: 63-83. Chew, F. 1955. 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Enami, S. 1940. Action melano-dilatatrice de l’adrenaline chez un silure chat, Parasilurus asotus. Proc. Imp. Acad. Tokyo, 16: 236-240. Fields, H. M. 1962. Pompanos ( Trachinotus ssp.) of South Atlantic Coast of the United States. U. S. Fish and Wildlife Service, Fish Bull., 62(207): 189-222. Fingerman, M. 1963. The control of chromatophores. Internat. Series Monographs Pure and Applied Biol., Div. Zool., 14: i-ix, 1-184. Fowler, H. W. 1907. A supplementary account of the fishes of New Jersey, Part 3, Ann. Rept. N. J. State Mus. for 1906, pp.: 251-350. 1931. A collection of fishes from the Texas coast. Coepia (2): 46-50. Fukui, K. 1927. On the color pattern produced by various agents in the goldfish. Folia Anat. Japo- nica, 5: 257-302. 1930. The definite localization of the color pat- tern in the goldfish. Ibid. 8: 283-312. Goode, G. B. 1884. Natural History of useful aquatic animals. Part 3 — Fishes. In The fisheries and fish- ery industries of the U. S., G. B. Goode [Ed.]. Section 1, pp.: 163-682. Gordon, M. 1948. Effects of five primary genes on the site of melanomas in fishes and the influence of two color genes on their pigmentation. In The Biology of Melanomas. R. W. Miner [Ed.], Special Pubs., N. Y. Acad. Sci., pp.: 216-267. 1957. Physiological genetics in fishes. In The Physiology of Fishes, M. E. Brown [Ed.], Academic Press, N. Y., 2: 431-501. Greenwood, P. H., D. E. Rosen, S. H. Weitzman, and G. S. Myers 1966. Phyletic studies of teleost fishes, with a provisional classification of living forms. Bull. Amer. Mus. Nat. Hist., 131(4): 339-456. Gudger, E. W. 1931. The triple-tail, Lobotes surinamensis, its names, occurrence on our coasts and its natural history. Amer. Nat., 65: 49-69. Gunter, G. 1945. Studies on the marine fishes of Texas. Pub. Inst. Mar. Sci., 1(1): 1-190. 1950. Correlation between temperature of water and size of marine fishes on the Atlantic and Gulf Coasts of the United States. Copeia (4) : 298-304. Gunter, G., and J. W. Ward 1961. Some fishes that survive extreme injuries and some aspects of tenacity of life. Ibid. (4): 456-462. Hamilton, W. J., and F. Heppner 1967. Radiant solar energy and the function of black homeotherm pigmentation: an hy- pothesis. Science, 155(3759): 196-197. Hildebrand, S. F., and L. E. Cable 1934. Reproduction and development of whit- ings or kingfishes, drums, spot, croaker, and weakfishes or sea trouts, family Sciae- nidae, of the Atlantic Coast of the United States. Bull. U. S. Bur. Fish., 48(16): 4-117. 1938. Further notes on the development and life history of some teleosts at Beaufort, N.C. Ibid. 49(24): 505-642. Hildebrand, S. F., and W. C. Schroeder 1928. Fishes of Chesapeake Bay. Ibid. 43(1): 1-366. Hu, F., and W. Chavin 1956. Induction of melanogenesis in vitro. Anat. Rec., 125(3): 600. Jordan, D. S., and B. W. Evermann 1896. The fishes of north and middle America. Bull. U. S. Nat. Mus. 47(1): 943. Kendall, W. C. 1908. Fauna of New England. List of the Pisces. 1969] B re tier: Aspects of Melanism in Acanthopterygian Fishes 131 Occ. Pap. Boston Soc. Nat. Hist. (7): 1-152. Kilby, J. D. 1955. The fishes of two Gulf coastal marsh areas of Florida. Tulane Stud., Zool. 2(8): 175-247. Kosto, B., G. E. Pickford, and M. Foster 1959. Further studies of the hormonal induc- tion of melanogenesis in the killifish, Fundulus heteroclitus. Endocrinology, 65(6): 869-881. Longly, W. H., and S. F. Hildebrand 1941. Systematic catalogue of the fishes of Dry Tortugas, Florida. Carnegie Inst. Wash., Pub. 535, Pap. Tortugas Lab., 34: i-xii, 1-331. Marsland, D. A. 1940. The effect of high hydrostatic pressure on the melanophores of the isolated scales of Fundulus heteroclitus. Anat. Rec., 78: 168. 1942a. Contractile mechanism in unicellular pig- mentary effects. Collectors Net, 17: 81-83. 1942b. The contractile mechanism in unicellular chromatophores (melanophores of Fun- dulus). Bio. Bull. Woods Hole, 83: 292. Meek, S. E., and S. F. Hildebrand 1925. The marine fishes of Panama. Field Mus. Nat. Hist. Pub. 226, Zool. Series, 15(2): xv-xix, 331-707. 1928. Ibid. (3): xx-xxxii, 708-1045. Mortensen, T. 1917. Observations on protective adaptations and habits, mainly in marine animals. Saertryuk Videns, Medd. Dansk. natur- hist. Foren., 69: 57-96. Muzlera, J. M. 1934. Accion de las temperatura sobre la pig- mentacion de Jenysia lineata (Jenyns) Gunther. Rev. Soc. Argent. Biol., 10: 369-370. Nichols, J. T., and C. M. Breder, Jr. 1926. The marine fishes of New York and southern New England. Zoologica, 9(1): 1-192. Odiorne, J. M. 1957. Color changes. In The Physiology of Fishes. M. E. Brown [Ed.], Academic Press, N. Y„ 2(8): 387-401. Osborn, C. M. 1941. Studies on the growth of integumentary pigment in the lower vertebrates, II. The role of the hypophysis in melanogenesis in the common catfish ( Ameiurus melas) . Biol. Bull. Woods Hole, 81: 352-363. OSTERHAGE, K. H. 1932. Morphologische und physiologische Stu- dien an Pigmentzellen der Fische. Zeit. mikr-anat. Forsch., 30: 551-598. Parker, G. H. 1948. Animal colour changes and their neuro- humors. A survey of investigations 1910 to 1943. Cambridge University Press: i-x, 1-377. Randall, J. E., and H. A. Randall 1960. Examples of mimicry and protective re- semblance in tropical marine fishes. Bull. Mar. Sci. Gulf and Caribbean, 10(4): 444-480. Rasquin, P. 1946. On the reappearance of melanophores in blind goldfish. Copeia (2): 85-91. 1958. Studies in the control of pigment cells and light reactions in recent teleost fishes. Bull. Amer. Mus. Nat. Hist., 115(1): 1-68. Rasquin, P., and L. Rosenbloom 1954. Endocrine imbalance and tissue hyper- plasia in teleosts maintained in darkness. Ibid. 104(4): 359-426. Reed, H. D., and M. Gordon 1931. The morphology of melanotic over- growths in hybrids of Mexican killifishes. Amer. Journ. Cancer, 15: 1524-1546. Reid, G. K., Jr. 1954. An ecological study of the Gulf of Mexico fishes in the vicinity of Cedar Key, Florida. Bull. Mar. Sci. Gulf and Carib- bean, 4(1): 1-94. Ryder, J. A. 1887. On the development of osseus fishes, in- cluding marine and freshwater forms. Rept. U. S. Comm., Fish and Fisheries, 1885. 489-604. SCHNEIRLA, T. C. 1959. An evolutionary and developmental the- ory of byphasic processes underlying ap- proach and withdrawal. In Nebraska Sym- posium on Motivation. M. R. Jones [Ed.], Univ. Nebraska Press, Lincoln, Neb.: 1-42. Smith, H. M. 1898. Fishes found in the vicinity of Woods Hole. Bull. U. S. Fish. Comm. 1897, 27: 85-111. 1907. The fishes of North Carolina. N. C. Geol. and Econ. Surv., 2: 1-453. Smith, D. C. 1928. The effect of temperature on the melano- phores of fishes. Joum. Exp. Zool., 52: 183-234. 132 Zoologica: New York Zoological Society [54:4 Smith, G. M. 1931. The occurrence of melanophores in cer- tain experimental wounds of goldfish ( Carassius auratus). Biol. Bull. Woods Hole, 61: 73-84. 1932a. Melanophores induced by X-ray com- pared with those existing in patterns as seen in Carassius auratus. Ibid., 63 : 484- 491. 1932b. Eruptions of corial melanophores and general cutaneous wounds in goldfish ( Carassius auratus ) following exposure to X-ray. Amer. Journ. Cancer, 16: 863-870. Springer, S., and H. R. Bullis, Jr. 1956. Collections of the Oregon in the Gulf of Mexico. U. S. Fish and Wildlife Serv., Special Sci. Rept. (196): 1-134. Springer, V. G., and A. J. McErlean 1962. Seasonality of fishes on a south Florida shore. Bull. Mar. Sci. Gulf and Carib., 12(1): 39-60. Springer, V. G., and K. D. Woodburn 1960. An ecological study of the fishes of the Tampa Bay area. Florida State Bd. Con- serv. Proff. Pap. Series (1): i-v, 1-104. Storer, D. H. 1867. A history of the fishes of Massachusetts. Cambridge and Boston: 1-287. Sumner, F. B. 1935. Evidence for the protective value of changeable coloration in fishes. Amer. Nat. 69: 245-266. Sumner, F. B., and P. Douderoff 1938. The effects of light and dark backgrounds upon the incidence of a seemingly in- fectious disease in fish. Proc. Nat. Acad. Sci. Wash. 24: 463-466. Sumner, F. B., R. C. Osburn, and L. J. Cole 1913. A biological survey of Woods Hole and vicinity. Bull. U. S. Bur. Fish., 31(2): 549-794. Townsend, C. H. 1929. Records of changes in color among fishes. Zoologica, 9(9): 321-378. Walls, G. F. 1942. The vertebrate eye. Bull. Cranbrook Inst. Sci. (19): i-xiv, 1-785. Willey, A. 1904. Feaf mimicry. Spolia Zealandica, 2: 51-55. Young, J. Z. 1935. The photoreceptors of lampreys. II. The functions of the pineal complex. Journ. Exp. Biol., 12: 254-270. EXPLANATION OF PLATE Plate I The black phase of Trachinotus falcatus. Three views of a single individual confined in a white basin. From top down; a typical posture in reference to two black spots; a net thrust under the fish, indi- cating its quiescent nature, despite the fact that the net necessarily displaced the fish in order to get under it; fingers thrust astride of the fish and wiggled, the latter activity being responsible for the surface ripples. See text for full explanation. BREDER PLATE I ASPECTS OF MELANISM IN ACANTHOPTERYGIAN FISHES 9 Color Pattern of the Eastern Pacific Spotted Porpoise Stenella graffmani Lonnberg (Cetacea, Delphinidae) William F. Perrin1 (Plates I-VII; Text-figures 1-3) Developmental, individual, and between-school variation in coloration is described. New- born are unspotted, and are dark-gray above and white below. Dark-gray ventral spots appear first at side of jaw and in area ahead of flipper, then develop rapidly over entire ventral surface. Ventral spots fuse in adults to yield uniform gray appearance below. Dorsal light-gray spots begin to develop after appearance of ventral spots and vary greatly in size and density in adults. System of markings about head, including eye patch, eye band, gape border, forward extension of cape mark, and flipper band, reach highest degree of contrast with ground coloration in subadults and persists only faintly in adults. Features that show great individual variation include extent of secondary dark-gray brush- ings on head of newborn and development of dorsal spotting in adults. Features showing variation between schools include structure of flipper band, definition of cape mark, definition of secondary light-gray band below cape mark, and color of tips of jaws. Colora- tion is similar to S. attenuate! except for contrast between components of pattern, but different from that of S. plagiodon. Introduction Porpoises of the genus Stenella are not only of high scientific interest, but are also important to the multimillion-dollar, California-based tropical tuna fishery. Two porpoises — the spotted Stenella graffmani (Lonn- berg), and a form called “spinner porpoise” by fishermen, assigned to S. microps (Gray) by Handley (Hester, Hunter, and Whitney, 1963) and to S. longirostris (Gray) by Nelson (1889) and Hershkovitz (1966) — and yellowfin tuna, Thunnus albacares (Bonnaterre) occur together in large school complexes in the eastern central Pacific. Fishermen locate the tuna by spotting the porpoise schools at the surface. The associa- tion between fish and the porpoise is very close, and the fish schools can be slowed, consolidated, and otherwise directed by herding the porpoise (Inter-American Tropical Tuna Commission, 1968; McNeely, 1961; Perrin, 1968). Despite their economic importance, little is known of the biology of either of the porpoises. The pres- ent report describes color pattern development 'Bureau of Commercial Fisheries, Fishery-Oceanog- raphy Center, La Jolla, California 92037. and color variation within and between schools of Stenella graffmani. Little has been recorded about the coloration of S. graffmani since it was described by Lonn- berg (1934) from a salted skin and part of the skull of a large male collected near Acapulco, Guerrero, Mexico. He described the skin as follows: “The colour of the skin, since the salt had been removed, was coal black all over but with small scattered, whitish-gray spots, chiefly on the back, and perhaps more numerous on the back behind the dorsal fin. On the lower parts of the sides these spots were much less numerous and much smaller in size than those of the back.” His figure of the type-specimen was based on a photograph of the dried skin after it had been partially prepared for mounting. The spotting described by Lonnberg is evident in his figure, but a characteristic ground pattern, described below, apparently was obliterated by the salting process. Hall and Kelson (1959), perhaps following Lonnberg’s description, described S. graffmani as “blackish throughout, mottled dorsally with grayish-white.” Walker ( 1964) published a good lateral photograph of what appears to have been 135 136 Zoologica: New York Zoological Society [54:4 a large adult female. The spotting pattern is easily seen, and some elements of the ground pattern are discernible. Ingles’ (1965) wash drawing is inaccurate in shape and coloration. A drawing published by Daugherty (1965) de- picts the shape of the animal more accurately but represents the color pattern poorly. She described the pattern as “. . . uniform gray, with scattered small spots of white or light gray. The spotting is variable, sometimes being quite con- spicuous, especially in certain body areas, at other times being hardly noticeable. It is un- doubtedly more distinct in live animals than in the dead ones which the tuna boats bring in.” The only previously published observation on the variation of coloration other than in adult specimens of S. graffmani is the report by Cald- well and Caldwell (1966) of an unspotted calf taken from the uterus of a spotted mother. As is shown below, this difference is a function of age. The inadequacy of the record can be laid to the difficulty of obtaining and studying specimens, especially fresh ones, of a tropical pelagic ceta- cean such as S. graffmani. American tuna fishermen have in recent years begun to use very large purse seines in areas where schools of S. graffmani are closely associated with tuna schools. This circumstance has lately made the species accessible to study. Materials and Methods This report is based on specimens, notes, and photographs that I collected during a cruise to the eastern central Pacific aboard a commercial tuna seiner, from April 1 to April 29, 1968. Fifteen net sets, numbered 1 to 15 (Text-fig. 1), were made on porpoise from tuna-porpoise as- sociations. Since deck space was required for examination of the animals, the amount of data that I could collect from a particular set de- pended on the time of day, the amount of fish in the net, and other factors that affected the fishing operation. Extensive observations on large numbers of animals could be made only when the net set was completed at or near the end of the fishing day; it was then possible to keep porpoise on deck until the following morn- ing. Some color observations were made on all 15 of the school samples, and more detailed notes were taken on 129 specimens from four schools. Extensive morphometric and ecological data that were gathered will be reported else- where. Text-fig. 1. Locations of net sets numbers 1-15. Stenella graffmani was taken in all sets except no. 14. 1969] Perrin: Color Pattern of the Eastern Pacific Spotted Porpoise Stenella graffmani Lonnberg 137 The degree of sexual development of 107 animals was estimated by a rapid field examina- tion of the gonads. Males with full-size testes (approximately 30 cm in length) were adjudged mature. The females that were not pregnant or lactating fell into two groups, those in which both ovaries were flat and obviously immature and those in which one or both ovaries were fully developed and contained corpora albicantia or maturing follicles. Since gonads were not examined histologically, the determinations of maturity must be considered estimates. Developmental and Individual Variation When a number of spotted porpoise from a single school are laid on the deck of a ship, the first impression is one of wide variation in coloration. In the schools I examined, however, the animals could be grouped roughly into the following five general categories of color pattern (PI. I): a. Newborn stage. Dark purplish-gray dorsal surfaces and lateral brushings, with white ventral surfaces and no spots; displayed by the smallest individuals, some of which retained shreds of umbilical cord. b. Two-tone stage. General two-tone pattern with dark-gray surfaces above, lighter-gray lower surfaces, and a well-defined pattern in varying shades of gray about the head and flippers; no spots. The individuals in this and the following two groups were progressively inter- mediate in size between the smallest (newborn) and largest animals. c. Speckled stage. Same as two-tone but with discrete, very dark-gray spots on the ventral surfaces; discrete light-gray spots on the upper, darker surfaces present on some animals but lacking on others. d. Mottled stage. Ventral spots converging and overlapping in places, but patches of the lighter- gray background still visible, yielding a mottled effect; discrete or merging light-gray spots pres- ent on the upper surfaces. e. Fused stage. Ventral spots completely con- vergent, to give the effect of a uniform, medium- gray to dark-gray surface; on close inspection, the individual overlapping spots still discernible; displayed by the largest individuals. These five categories represent definable in- crements in a continuous development of colora- tion. The rather close correlation between these pattern categories and the size of the animals (Text-fig. 2) demonstrates clearly that the pri- mary component of the spotting variation is developmental. An alternative explanation — that size, and therefore spotting development, are independent of age — is eliminated by data on maturity (Table 1). None of the two-tone or speckled animals were sexually mature; nearly one-third of the mottled animals were mature; and all but one of the fused individuals were mature. This sequence indicates that the onset of sexual maturity occurs during or shortly after the mottled stage. Color of Newborn Animal The newborn animal (PI. II, fig. 2) is dark- gray above and creamy-white below. The bound- ary of a well-defined mark, referred to below as the cape mark, extends from the apex of the melon, over the eye, to behind the dorsal fin. In the latter area, approximately one-fourth of the distance from the dorsal fin to the flukes, the boundary is less sharply delineated. In lateral view, the cape extends approximately two-thirds of the way down the side of the animal above the anterior insertion of the dorsal fin. The area from the vertical through the genital region to the flukes is sharply divided along a line that runs forward from the lateral fluke origin into a dark-gray area above and a lighter portion below. The area below the line shades from white above the anus to dark-gray Text-fig. 2. Relationship between size and develop- ment of ventral spotting in 129 specimens of Stenella graffmani. Sample size is shown in paren- theses. 138 Zoologica: New York Zoological Society [54:4 Table 1. Relationship Between Sexual Maturity and Development of Ventral Spotting in 102 Specimens of Stenella graffmani Males Females Color pattern Number examined Number mature Number examined Number mature Two-tone 12 0 11 0 Speckled 4 0 5 0 Mottled 14 1 10 6 Fused 13 12 33 33 at the fluke origin. The gray of the upper half of the divided area extends forward and into the cape region, but the margin there is more diffuse. A narrow, diffuse streak of the same shade of gray arises from the lower margin of the dark area at approximately above the posterior in- sertion of the flipper. It extends posteriorly and slightly into the white area below the cape. Seen from below, the pure white of the lower surface narrows to a line along the ventral keel at about half the distance between the anus and the fluke notch. The white edging extends to the end of the keel. Coloration about the eye is distinctive. A dark eye patch is drawn out at its forward margin into a narrow eye band which extends forward along the rostral groove and joins the cape mark near the apex of the melon. This well-defined eye marking is overlaid with a more extensive diffuse marking of lighter-gray. There are brush- ings of the same gray color on the upper side of the snout and on both sides of the lower jaw. Individual variation is great in the width and definition of the eye band and in the extent of the lighter-gray overlaid markings (PI. II, fig. 3) . Animals with extensive brushing around the eye also have a faint suggestion of a broad, very diffuse band extending from the eye region to the flipper origin. The flippers and flukes are dark-gray on both surfaces, and the dorsal fin is also uniform dark-gray. Inferred Development of Coloration As the porpoise increases in size, the entire region below the cape mark darkens to a light- gray (PI. II, fig. 4). The secondary brushings about the eye and snout are no longer evident. The eye band becomes part of a well-defined system of connected markings (Text-fig. 3) that includes a dark margin around the most posterior part of the gape and the dark flipper band, which extends from the gape to the anterior insertion of the flipper. This pattern persists throughout further development. Anteriorly the lower margins of the flipper bands extend ventrally, becoming confluent in the gular area about four-fifths of the distance from the tip of the snout to the end of the gape. There is great interschool variation in the extent and delineation of the flipper band (discussed below). Parallel to the margin of the cape mark is a narrow lighter-gray band, approximately as wide as the eye patch (PI. Ill, fig. 5). The band dis- appears approximately below the dorsal fin tip; definition of the band varies among schools. The next event in the developmental sequence is the appearance of dark-gray spots on the ventral surfaces. The spots appear first on the side of the lower jaw and in the flipper band near the anterior insertion of the flipper (PI. Ill, fig. 6). They seem to appear rapidly during growth over the entire ventral surface, but re- main densest on the mandible and in the flipper band (PI. IV, fig. 7). The spots become larger and begin to overlap (PI. V, figs. 8 and 9), and the flipper bands become less evident (PI. VI, figs. 10 and 11). At this stage, the animal has a mottled appearance below. The spotting may extend to both surfaces of the flippers. Indi- vidual variation in regularity of size and spacing of the spots results in variable appearance of the ventral aspect during the mottled stage. As growth proceeds, the spots coalesce least rapidly in the gular and genital regions. When fusion is complete, the spots are no longer clearly evident and the animal appears uniform gray below (PI. VI, figs. 10 and 11), although the spots may still be detected upon close inspection. The pat- tern about the head, including the eye band and flipper band, is still apparent, but faint. After the ventral dark spots have appeared, very light-gray spots become evident on the dark-gray dorsal surfaces (PI. V, fig. 8). Their size and number rapidly increase, and they be- come densest and may overlap at the margin of the cape mark above the eye and in the area immediately posterior to the cape mark (PI. VI, figs. 10 and 1 1, and PI. VII, fig. 12). The density of light spots in these areas and over the rest of the upper surfaces, once the fused stage has been reached, varies within a school (PI. VII, fig. 13) and bears no apparent relationship to the size of the animal. In some individuals, the light spotting extends to the area below the cape mark. Between-School Variation In addition to the developmental and indi- vidual variation within schools, I observed between-school variation in several features: 1. The structure of the flipper band varied be- tween schools from a simple band (PI. II, fig. 4) to a wider, more complex structure (PI. Ill, fig. 6). 2. The narrow light-gray band contiguous to the cape mark was very strongly defined in the subadults of some schools (PI. Ill, fig. 5). The 1969] Perrin: Color Pattern of the Eastern Pacific Spotted Porpoise Stenella graffmani Lonnberg 139 Text-fig. 3. Pattern on head of adult Stenella graffmani, with explanation of terms used in text. Sketched from female, 195 cm, from set no. 7. presence of this band was correlated with a poorly defined upper margin of the flipper band. 3. The contrast between the cape mark and the lighter lower surfaces varied. The larger individuals taken in set number 5 appeared at first sight to be uniform dark-gray with light dorsal spots. Closer inspection, however, re- vealed a faint cape mark. 4. In some schools, the larger adults had white-tipped jaws (PI. VII, fig. 14), correlated with a faint light-gray flecking of the dark-gray ventral surface, especially in the gular region. On the basis of color notes and photographs, I scored each of five schools for each of these four features (Table 2). Fraser (1966) posed a stimulating question about schools of tropical Stenella species. He asked, “Are the dolphins fortuitously congre- gated for some purpose such as feeding, breed- ing, or deriving benefit from especially favorable environmental conditions? Or is each school formed by the natural increase of an isolated family unit?” The between-school differences in coloration detected in S. graffmani suggest that schools of this species may constitute genetic entities. Between-school variation in skeletal and external morphometric characters has yet to be examined for any of the spotted porpoises. Comparison with Other Forms The developmental sequence in color pattern parallels that described for Stenella plagiodon (Cope)- by Caldwell and Caldwell (1966) ex- cept that in S. plagiodon the ventral dark spots do not become fused. The adults figured by the 2 Placed in the synonymy of S. pernettyi (Blaineville) by Hershkovitz (1966). 140 Zoologica: New York Zoological Society [54:4 Table 2. Between-School Variations in Color Pattern of Specimens of Stenella graffmani from Six Schools The symbol — indicates feature absent or so poorly defined as to appear absent; + indicates feature present and sufficiently well-defined to be readily observable; + + indicates feature was strikingly well-defined. School (set number) and (in parentheses ) number of animals examined Feature 4 (33) 5 (31) 8 (92) 9 (183) 11 (34) 12 (48) 1. Complex flipper band — — + + + + 2. Secondary light band below cape + - + + - + 3. Contrast between cape and ground + + — + + + + 4. White jaw tips - - + + + + - Caldwells and others (True, 1885; McBride, 1940; Moore, 1953) are all spotted or mottled below. Other differences in pattern are evident from the photographs; In S. plagiodon the ventral ground is white rather than light-gray; the lateral and dorsal light spotting is developed to a higher degree; the cape mark is apparently present in the unspotted juvenile but is not evident in the photographs of older, spotted ani- mals; and a light line runs from the eye to the posterior insertion of the flipper in unspotted young specimens (absent in S. graffmani) . The coloration of the other common spotted porpoises, S. attenuata (Gray)3 in the south Atlantic and central and western Pacific and S. frontalis (Cuvier) in the Atlantic, is less well known than that of S. plagiodon. Photographs of S. attenuata from Japan (Nishiwaki, Naka- jima, and Kamiya, 1965) show a cape mark and eye and flipper hands like those of some indi- viduals of S. graffmani. In reference to spotting, Nishiwaki et al. stated . . the dorsal half of the body is blueish purple black with numerous gray and white spots, and the ventral half of the body is gray with numerous tiny white spots. There are no spots on the head, the dorsal fin, the flippers, and the tail flukes.” The jaw tips are white. The contrast between the cape mark and the lighter area below appears to be much stronger than in S. graffmani. In the specimens of S. graffmani that I examined, white jaw tips and white-flecked ventral surfaces were present in some schools, and the degree of light spotting in the dorsal region varied within schools; con- sequently, the only consistent difference in coloration between the specimens of S. attenuata which Nishiwaki et al. figured and those of S. graffmani described in the present paper is in the degree of contrast between the cape mark and the area below. 3 Placed in the synonymy of S. dubia (Cuvier) by Hershkovitz (1966). Dawbin (1966) published a photograph of six spotted porpoises (heads only) taken by natives on the island of Malaita in the Solomons. He assigned these animals to “the S. attenuata- frontalis group.” The portion of the color pattern that can be seen corresponds to the pattern in S. graffmani in every respect. A specimen of S. frontalis from the coast of French Equatorial Africa that Fraser (1950) described in great detail did not differ in color pattern from S. graffmani. The jaw tips were white, and the ventral surface was “. . . dark gray with abundant darker spots and fewer scattered white spots.” Fraser cited the fact that Lonnberg’s (1934) description of the type of S. graffmani did not mention a white snout tip and chin and concluded, “It is only in the fleck- ing on the body that this species can, by color, be connected with the ‘Atlantide’ specimen — S. frontalis.” White snout tips, as noted above, occur in some individuals of 5. graffmani. This feature has now been noted in all the spotted porpoises (Nishiwaki, 1965; Dawbin, 1966; Caldwell and Caldwell, 1966). Of three spotted porpoises from West Africa that Cadenat (1959) described, one that he tentatively referred to as S. frontalis corresponds to S. graffmani in coloration. The remaining two more closely resemble the specimens of S. plagiodon depicted by Caldwell (1966), and he indeed tentatively referred one of them to that species. The closely similar or identical color patterns of the nominal species of spotted porpoises point out the need for intensive and standardized ob- servations on large series of these animals. From my observations on S. graffmani and from previously published descriptions and figures of color patterns in S. frontalis and S. attenuata, I see no basis at present for separation of these three forms by coloration. This is not to say that they may not prove to be separable on the basis of other characters. 1969] Perrin: Color Pattern of the Eastern Pacific Spotted Porpoise Stenella graffmani Lonnberg 141 The conclusions reached here are tentative, because they are based on data for a relatively small number of schools from a restricted por- tion of the geographical range of the species. Definition of the total range of variation and more accurate delineation of the developmental, individual, and between-school components of variation must await the availability of larger series, from throughout the range. Acknowledgments This study was supported by the Bureau of Commercial Fisheries and the Zoology Depart- ment of the University of California at Los Angeles. Kenneth S. Raymond prepared Text- figs. 1, 2, and 3. PI. 1 was painted by George M. Mattson. Dr. Kenneth S. Norris and Dr. Carl L. Hubbs read the manuscript and made many helpful suggestions. Collection of the data was made possible through the cooperation and as- sistance of the owners, captain, and crew of the tuna boat Carol Virginia. Literature Cited Cadenat, J. 1959. Rapport sur les petits Cetaces ouest- Africains. Resultat des recherches entre- prises sur ces animaux jusqu’a mois de mars 1959. Bull. IFAN, 21(A): 1367-1409, PI. I-XXXI. Caldwell, D. K., and M. C. Caldwell 1966. Observations on the distribution, colora- tion, behavior and audible sound produc- tion of the spotted dolphin, Stenella plagiodon (Cope). Los Angeles Co. Mus. Contr. Sci., 104:1-28. Daugherty, A. 1965. Marine mammals of California. California Dept. Fish and Game, Sacramento, 86 pp. Dawbin, W. H. 1966. Porpoises and porpoise hunting in Malaita. Austral. Nat. Hist., 1 5 : 207-2 1 1 . Fraser, F. C. 1950. Description of a dolphin Stenella frontalis (Cuvier) from the coast of French Equa- torial Africa, p. 62-84, PI. I. In Atlantide — Report No. 1. Scientific results of the Danish Expedition to the coast of tropical West Africa 1945-1946. Danish Science Press, Copenhagen. 1966. Comments on the Delphinidae, p. 7-31. In K. S. Norris [ed.], Whales, dolphins, and porpoises. Univ. California Press, Berkeley and Los Angeles. Hall, E. R., and K. R. Kelson 1959. The mammals of North America. Ronald Press Co., New York, 2: 1083 pp. Hershkovitz, P. 1966. Catalog of living whales. U.S. Nat. Mus. Bull., 246:1-259. Hester, F. J., J. R. Hunter, and R. R. Whitney 1963. Jumping and spinning behavior in the spinner porpoise. J. Mamm., 44:586. Ingles, L. G. 1965. Mammals of the Pacific states. Stanford Univ. Press, Stanford, California, 506 pp. Inter-American Tropical Tuna Commission 1968. Annual report for 1967. La Jolla, Cali- fornia, 143 pp. Lonnberg, E. 1934. Prodelphinus graffmani n.s. a new dolphin from the Pacific coast of Mexico. Ark. for Zool. 26(A): 1-11, PI. I. McBride, A. F. 1940. Meet mister porpoise. Nat. Hist., 45: 16-29. McNeely, R. L. 1961. The purse seine revolution in tuna fishing. Pacific Fisherman. June, 1961 :27-58. Moore, G. C. 1953. Distribution of marine mammals to Florida waters. Amer. Midland Nat., 49:117-158. Nelson, E. W. 1899. Mammals of the Tres Marias Islands. N.A. Fauna, 14: 1-97. Nishiwaki, M., M. Nakajima, and T. Kamiya 1965. A rare species of dolphin (Stenella at- tenuata) from Arari, Japan. Sci. Rep. Whales Research Inst., 19:53-64. Perrin, W. F. 1968. The porpoise and the tuna. Sea Frontiers, 14(3) : 166-174. True, F. W. 1885. IV. On a spotted dolphin apparently identical with the Prodelphinus doris of Gray. U.S. Nat. Mus. Ann. Rep., 1884, Part 11:317-324, PI. I-IV. Walker, E. P. 1964. Mammals of the world. John Hopkins Press, Baltimore, Maryland, 2: 1500 pp. 142 Zoologica: New York Zoological Society [54:4 Fig. 1 Fig. 2 Fig. 3 Fig. Fig. Fig. EXPLANATION OF PLATES Plate I Development of color pattern in Stenella graffmani, showing observable increments described in text: a. newborn, b. two-tone, c. speckled, d. mottled, e. fused. Painted by George M. Mattson from photographs and field notes. Plate II Newborn Stenella graffmani, female, total length (tip of snout to fluke notch) 87cm. From set no. 5. Lateral views of heads of four newborn female specimens of Stenella graffmani from set no. 5. Lengths from left to right: 85 cm, 85 cm, 87 cm (same animal shown in Fig. 2), 86 cm. Note variation in mark- ings about the eye. In the first three indi- viduals the basic dark eye band is overlaid with a more diffuse and more extensive marking of lighter gray. Subadult Stenella graffmani at two-tone stage. Female, 141 cm, from set no. 5. The scattered white flecks are adhering fish scales. Plate III Stenella graffmani at two-tone stage, show- ing light band below the cape mark. From set no. 8. Sex and length data for this specimen and for others of those figured below were not gathered. The reason for these gaps in the data is explained in the text. Stenella graffmani, showing early stage of ventral spot development. From set no. 11. Plate IV Fig. 7. Lateral views of head, middle, and tail regions of Stenella graffmani at the speckled stage. Female from set no. 11. The white flecks are adhering fish scales. Plate V Fig. 8. Stenella graffmani at mottled stage. Fe- male, 1 84 cm, from set no. 12. Fig. 9. Ventral views of Stenella graffmani at early speckled (lower) and mottled stages. Female (lower), 163cm; and male, 165cm, from set no. 10. Plate VI Fig. 10. Adult Stenella graffmani at fused stage with light dorsal and lateral spotting. Male, 1 87 cm, from set no. 12. Fig. 1 1. Ventral views of three adult specimens of Stenella graffmani at fused stage, from set no. 9. From bottom: male, 200cm; female, 183 cm; female, 176cm. Plate VII Fig. 12 Stenella graffmani with heavy dorsal and lateral spotting. From set no. 10. Fig. 13. Sample from one school of Stenella graff- mani on deck of tuna seiner. Note varia- tion in dorsal and lateral spotting. Fig. 14. Large adult Stenella graffmani, showing white jaw tips and lips. From set no. 11. PERRIN PLATE I FIG. 1 COLOR PATTERN OF THE EASTERN PACIFIC SPOTTED PORPOISE STENELLA GRAFFMANI LONNBERG (CETACEA, DELPHINIDAE) PERRIN PLATE II COLOR PATTERN OF THE EASTERN PACIFIC SPOTTED PORPOISE STENELLA GRAFFMANI LONNBERG (CETACEA, DELPH1NIDAE) FIG. PERRIN PLATE III FIG. 6 COLOR PATTERN OF THE EASTERN PACIFIC SPOTTED PORPOISE STENELLA GRAFFMANI LONNBERG (CETACEA, DELPHINIDAE) PERRIN PLATE IV FIG. 7 - > ' 0 . COLOR PATTERN OF THE EASTERN PACIFIC SPOTTED PORPOISE STENELLA GRAFFMAN! LONNBERG (CETACEA, DELPHINIDAE) PERRIN PLATE V FIG. 9 COLOR PATTERN OF THE EASTERN PACIFIC SPOTTED PORPOISE STENELLA GRAFFMANI LONNBERG (CETACEA, DELPHINIDAE) PERRIN PLATE VI FIG. 11 COLOR PATTERN OF THE EASTERN PACIFIC SPOTTED PORPOISE STENELLA GRAFFMANI LONNBERG (CETACEA, DELPHIN1DAE ) PERRIN PLATE VII FIG. 13 COLOR PATTERN OF THE EASTERN PACIFIC SPOTTED PORPOISE STENELLA GRAFFMANI LONNBERG (CETACEA, DELPHINIDAE) [1969] Zoologica: Index to Volume 54 151 Numbers in parentheses are the series numbers of papers contain- ing the tables, figures, or plates listed immediately following; numbers in bold face indicate text-figures; names in bold face indicate new genera, species, or subspecies. A acanthopterygian fishes, see melanism B Balanus eburneus and B. bala- noides, parasites of, from New York Harbor, and a review of the parasites and diseases of other Cirripedia, 95-103, (7) Tables 1-5, (7) Plate I discussion, 100 fungus and lichens, 98-99 gregarinida, 95-97 isopoda, 98 summary, 100 trematoda, 97 turbellaria, 99-100 barnacles, studies on the biology of; parasites of Balanus ebur- neus and B. balanoides from New York Harbor and a review of the parasites and diseases of other Cirripedia, 95-103, (7) Tables 1-5, (7) Plate I birds, small, direct measurement of C02 production during flight, 17-23, (2) 1, (2) Tables 1-3 discussion, 19-23 methods of study, 18 results, 19 C Carassius auratus, a study of ex- perimentally induced endocy- tosis in a teleost: I. light micro- scopy of peripheral blood cell responses, 25-34, (3) 1, (3) Table 1, (3) Plates I-III discussion, 28-31 materials and methods, 26 observations, 26-28 summary, 31 Cirripedia, see Balanus eburneus CO- production, direct measure- ment of, during flight in small birds, 17-23, (2) 1, (2) Tables 1-3 discussion, 19-23 methods of study, 18 results, 19 Cyclophoridae, family, some Mexi- can and Central American land snails of. 35-77, (4) 1-14, (4) Plates I- VII subfamily Megalomastominae Kobelt and Mollendorff, 37-39 Aperostoma mexicanum sal- leanum (Martens), 37-39 A. palmeri (Bartsch and Morrison), 39 Farcimen (Neopupina) crofe- um (Gmelin), 39 Tomocyclus, 37 INDEX subfamily Neocyclotinae Kobelt and Mollendorff, 1898; 39-76 Amphicyclotus Crosse and Fischer, 1879; 56-64 A. megaplanus Morrison, 63-64 A. parvus Thompson, 63 A. paulsonorum new spe- cies, 61-63 A. texturatus spiralis, 59-61 A. t. texturatus (Sowerby), 56-59 Barbacyclus Bartsch and Mor- rison, 64 B. princeps (Pilsbry), 64 Dicrista new genus, 42-53 D. cooperi (Tryon), 54-47 D. damianensis (Solem), 47- 48 D. flavescens new species, 49-51 D. indentata new species, 51- 52 D. liobasis new species, 48- 49 D. petersi (Solem), 52 D. rugosa new species, 52- 53 Mexcyclotus lutescens (Pfeif- fer), 41-42 N eocyclotus Fischer and Crosse, 1886; 64-76 subgenus Incidostoma Bartsch and Morrison, 73-76 N. (1.1 carmioli (Bartsch and Morrison), 74 N. (I.) impressus new species, 75-76 N. (I.) irregulare (Pfeif- fer), 74 subgenus Neocyclotus Fischer and Vrosse, 1886; 65-73 N. bisinuatus (Martens), 71-73 N. capscelius new spe- cies, 73 N. dysoni ambiguum (Martens), 66 N. d. dyer i (Bartsch and Morrison), 68 N. d. dysoni (Pfeiffer), 66-68 N. d. nicaragu ense (Bartsch and Morrison), 68 N. simplicostus new species, 68-71 Xenocyclus new genus, 53- 56 X. patulus new species, 54-56 Cynolebias bellottii Steindachner, laboratory studies on life-span, growth, aging, and pathology of the annual fish, 1-16, ( 1 ) 1-4, (1) Tables 1-5, (1) Plates I-III discussion, 6-12 material and methods, 1-2 results, 2-6 aging and pathology, 4-6 egg production, 4 growth, 3-4 pathology, 6 survival and life-span, 2-3 summary and conclusion, 12- 13 E endocytosis, experimentally in- duced in a teleost, a study of, I. light microscopy of peripheral blood cell responses, 25-34, (3) 1, (3) Table 1, (3) Plates I-III discussion, 28-31 materials and methods, 26 observations, 26-28 summary, 31 Erignathus (bearded seal), un- derwater song of, 79-83, (5) 1, (5) Plates I-III, (5) Phono- graph disk acoustical results, 80-81 behavioral observations, 81- 82 summary and conclusions, 82 K killifish, intact ( Fundulus heter- oclifus), as a tool for medi- cally oriented study of marine neurotoxins, 85-94, (6) 1, (6) Table 1, (6) Plates I-II discussion, 88-90 materials and methods, 86-87 relevant previously known facts, 85-86 results, 87-88 summary, 90 M melanism aspects of in acanthop- terygian fishes, 105-133, (8) 1-6, (8) Tables 1-3, (8) Plate I discussion, 120-128 environmental circumstan- ces, 121-124 physiological circumstan- ces, 124-126 survival values, 126-128 experimental procedures, 116- 120 in plastic basins, 116-117 in variable light aquarium, 117-120 natural occurrence of melan- istic individuals, 105-113 principal cases, 106-113 Chaetodipterus taber (Broussonet), 109-113 Lagodon rhomboides (Linnaeus), 107 Menticirrhus, 107-109 Trachinotus falcatus (Linnaeus), 106-107 other cases, 113-116 summary, 128 P parasites, see Balanus eburneus porpoise, eastern Pacific spotted ( Stenella grattmani Lonnberg), color pattern of, 135-149, (9) 1-3, (9) Tables 1-2, (9) Plates I-VII r 1969] Zoologica: Index to Volume 54 152 between-school variation, 138- 139 comparison with other forms, 139- 141 developmental and individ- ual variation, 137-138 S seal, bearded (Erignafhus), un- derwater song of, 79-83, (5) 1, (5) Plates I-III, (5) Phono- graph disk acoustical results, 80-81 behavioral observations, 81- 82 summary and conclusions, 82 snails, land (Mexican and Central American}, see Cyclophoridae Stenella graftmani Lonnberg, col- or pattern of the eastern Pacific spotted porpoise, 135-149, (9) 1-3, (9) Tables 1-2, (9) Plates I-VII between-school variation, 138- 141 comparison with other forms, 139- 141 developmental and individ- ual variation, 137-138 NEW YORK ZOOLOGICAL SOCIETY The Zoological Park, Bronx, N. 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