r a I B R.AR.Y OF THE UNIVERSITY Of ILLINOIS cr> 52)0.5 CO FI 3 v.3G BIOLOGY The person charging this material is re- sponsible for its return on or before the Latest Date stamped below. Theft, and mutilation, underlining of books are reasons for disciplinary action and may result ,n dismissal from the University University of Illinois Library M^a^m UM*^V L161 O-1096 36 .2 THE DISTRIBUTION OF FISHES FOUND BELOW A DEPTH OF 2000 METERS MARION GREY FIELDIANA: ZOOLOGY VOLUME 36, NUMBER 2 Published by CHICAGO NATURAL HISTORY MUSEUM JULY 30, 1956 NAT. HIST. r THE DISTRIBUTION OF FISHES FOUND BELOW A DEPTH OF 2000 METERS MARION GREY Associate, Division of Fishes THE LIBRARY OF THE AUG H 1966 FIELDIANA: ZOOLOGY UHWB8I1Y OF ILLINOIS VOLUME 36, NUMBER 2 Published by CHICAGO NATURAL HISTORY MUSEUM JULY 30, 1956 PRINTED IN THE UNITED STATES OF AMERICA BY CHICAGO NATURAL HISTORY MUSEUM PRESS WD X^ CONTENTS PAGE Introduction 77 Terminology 78 Fishes found below 3660 meters 78 Distinctive character of deep-abyssal fauna 82 Endemism in deep-abyssal waters 83 Endemism of species 84 The bathypelagic fishes 88 Conclusion 92 Note 93 Editorial note 93 Acknowledgments 93 Synonymies and Distribution 94 Scylliorhinidae 94 Squalidae 95 Rajidae 98 Chimaeridae 100 Rhinochimaeridae 101 Alepocephalidae 102 Searsiidae 116 Gonostomatidae 119 Bathylaconidae 127 Harpadontidae 128 Chlorophthalmidae 129 Bathypteroidae 130 Ipnopidae 135 Eurypharyngidae 137 Simenchelyidae 139 Nettastomidae 140 Congridae 142 Ilyophidae 142 Synaphobranchidae 143 Serrivomeridae 148 Nemichthyidae 149 Cyemidae 151 75 76 CONTENTS PAGE Halosauridae 152 Notacanthidae 156 Moridae 158 Gadidae 161 Macrouridae 162 Stephanoberycidae 190 Melamphaidae 191 Acropomatidae(?) 192 Parapercidae 193 Chiasmodontidae 193 Bathydraconidae 194 Zoarcidae C . 194 Lycodapodidae 201 Derepodichthyidae 202 Brotulidae 202 Scorpaenidae 222 Cottidae 222 Cottunculidae 223 Liparidae 223 Triacanthodidae 228 Chaunacidae 229 Ogocephalidae 229 Ceratioidea 231 Caulophrynidae 232 Melanocetidae 234 Himantolophidae 239 Diceratiidae 242 Oneirodidae 243 Centrophrynidae 261 Ceratiidae 261 Gigantactinidae 266 Neoceratiidae 269 Linophrynidae 270 Tables Showing Vertical Distribution of Species 280 List of Benthic Fishes Found Below 1000 Fathoms 304 List of Bathypelagic Fishes Found Below 1000 Fathoms 311 References 313 Addendum 320 Index 321 The Distribution of Fishes Found Below a Depth of 2000 Meters INTRODUCTION In The Depths of the Ocean (Murray and Hjort, 1912, p. 414) Dr. Johan Hjort published a list of fishes believed to live upon the ocean floor at depths exceeding 2000 fathoms (3660 meters). The list contained twenty-one species belonging to six families, with only thirty-five individuals known. A check of Hjort's list in the light of subsequent knowledge reveals that two of the species, Bathypterois longicauda Gunther and Macrurus gigas Vaillant, have been reduced to synonymy, and that one, Histiobranchus infernalis Gill, was erroneously included and has never actually been reported from waters below 3660 meters. Aleposomus copei Gill is undoubtedly a bathypelagic fish, with its center of distribution well above the 2000-meter line. Thus, of the species listed by Hjort, only seventeen that can with any degree of certainty be referred to as benthic fishes are found below a depth of 3660 meters. A survey of the literature published since 1912 adds to Hjort's list twenty-one species that probably live on bottom, thus raising the present total to a possible thirty-eight species, divided among eleven families and thirty genera, and represented by about 120 specimens actually caught below 3660 meters. The increase is small, but the technical difficulties and costliness of fishing at such great depths have not lessened in the intervening years and little such work has been carried out, especially in comparison with the large amount of fishing accomplished at higher levels in the deep sea. There are still some unidentified collections made by the United States Fisheries Steamer Albatross in Pacific waters, as well as recent collections made by Swedish, Russian, and Danish oceano- graphic expeditions. Dr. A. F. Bruun has written (1952, in litt.) that the results of the Galathea Expedition (1950-52) will alter some of the findings noted in this paper, extending the ranges of 77 78 FIELDIANA: ZOOLOGY, VOLUME 36 some of the species listed here and adding new species to the list. The Danish expedition concentrated on abyssal benthic trawling in many different parts of the world, returning with a large collec- tion of fishes and invertebrates. Although the Galathea results and other reports will add greatly to our knowledge, much further research will be necessary before we can attain a clear or complete picture of life at these great depths. Research on deep-sea life is still in its infancy. New forms are found so frequently that more obviously remain to be discovered, and it will be many years before enough benthic material has been gathered from deep-abyssal waters to allow detailed distributional studies. r TERMINOLOGY The terms archibenthic (between 200-400 and about 1000 meters) and abyssal (below 1000 meters) are used here as defined by Ekman (1935, 1953). The name deep-abyssal has been added to denote those areas of the sea lying below a depth of about 2000 meters. Nybelin (1953) has proposed the term eu-abyssal for the fauna found below about 4000 meters. Hjort defined the abyssal plain as those areas of the ocean floor below a depth of 2000 fathoms (3660 meters), the regions between 1500 and 2000 fathoms being, for fishes, a transition zone between the plain and the continental slope. It seems useful to include among the deepest-living fishes those found below a depth of 2000 meters, and this deep-abyssal fauna is treated in the following discussion. Species ranging to 1000 fathoms (1829 meters) are included, since the 1000-fathom line has been used as often as the 2000-meter line to divide deep-sea zones. These divisions are arbitrary in any case. It is known that the vertical boundaries of deep-sea zones vary considerably in different areas but inadequate knowledge of the fauna prevents a precise definition of these zones. FISHES FOUND BELOW 3660 METERS Hjort pointed out that benthic species recorded from the abyssal plain, and also known from more than one catch, have wide ranges both vertically and horizontally. Thus, Nematonurus armatus has an extreme vertical range of 282 to 4700 meters. Its geographical distribution is also wide, specimens having been reported from both sides of the Atlantic, in the central and southern parts of the Pacific, and in the southern Indian Ocean. Similar examples will be found in the discussion of individual species, but there are also species GREY: DISTRIBUTION OF DEEP-ABYSSAL FISHES 79 known from several hauls of which none were above the deep-abyssal zone (Bathysaurus mollis, Synaphobranchus bathybius, Lionurus filicauda and others). Bathymicrops regis, Bassozetus taenia and Grimaldichthys profundissimus have been caught several times each, and only on the abyssal plain. These three species have been taken only in the north Atlantic and are not, as yet, known to have a wide SEA LEVEL 80 FIELDIANA: ZOOLOGY, VOLUME 36 Family BATHYLACONIDAE *Bathylaco nigricans Goode and Bean Family HARPADONTIDAE Bathysaurus mollis Gunther Family BATHYPTEROIDAE Bathypterois longipes Gunther Family IPNOPIDAE Bathymicrops regis Hjort and Koefoed Ipnops murrayi Gunther *Bathymicrops sewelli Norman r Family SYNAPHOBRANCHIDAE *Synaphobranchus bathybius Gunther Family HALOSAURIDAE *Aldrovandia rostrata Gunther Family MACROURIDAE *Nematonurus abyssorum Gilbert Chalinura brevibarbis Goode and Bean Nematonurus armatus Hector Lionurus filicauda Gunther 1 *Chalinura liocephala Gunther Nezumia sclerorhynchus Valenciennes Chalinura Simula Goode and Bean Cetonurus globiceps Vaillant Chalinura carapina Goode and Bean *Echinomacrurus mollis Roule Family STEPHANOBERYCIDAE Acanthochaenus luetkeni Gill *Malacosarcus macrostoma Gunther Family ZOARCIDAE *Lycenchelys albus Vaillant *Pachycara obesa Zugmayer Family BROTULIDAE *Barathrites abyssorum Roule Mixonus laticeps Gunther Bassogigas crassus Vaillant Grimaldichthys profundissimus Roule Bassogigas digittatus Garman *Grimaldichthys squamosus Roule *Bassogigas brucei Dollo *Typhlonus nasus Gunther *Alcockia rostrata Gunther *Leucochlamys cryptophthalmus Zug- Bassozetus taenia Gunther mayer The following species have not been included in the above list because in each case the one record from below 3660 meters must be ignored in the face of overwhelming evidence that the species are well known at much higher levels: Hymenocephalus italicus Giglioli, 1 See footnote, page 79. GREY: DISTRIBUTION OF DEEP-ABYSSAL FISHES 81 discussed below with the fauna found below 2000 meters; Dicrolene introniger Goode and Bean, a species of shallower water, of which one damaged specimen has been reported from 5000 meters (Koe- foed, 1927, p. 134); and Ventrifossa petersoni Alcock, a common archibenthic macrourid of the Indo-Pacific region, of which a dam- aged specimen, probably misidentified, was once reported from 4391 meters (Weber, 1913, p. 156). Of the eleven families reported from the ocean floor below 3660 meters, macrourids and brotulids together make up slightly more than half of the species, while macrourids predominate in the number of individuals caught (about forty). However small the numbers seem, it is to be remembered, as Hjort wrote in 1912, that evidence of the scarcity