AALPH I SMITH- FDITQP Spe FOR REFERENCE Do Not Take From This Room Ql 573 .3 o- KEYS TO MARINE INVERTEBRATES of the WOODS HOLE REGION A manual for the identification of the more common marine invertebrates, compiled by Ralph I. Smith with the assistance of many other contributors m lor X. ; ru 5: j o " o CD- S' i a z nn § a Contribution No. 11 LL Systematics-Ecology Program, Marine Biological Laboratory Woods Hole, Massachusetts 1964 J CO Copyright 1964 by the Marine Biological Laboratory Tenth Edition Referrals To Marine Biological Laboratory Supply Dept. Woods Hole, Massachusetts 02543 Printed by Spaulding Co., Inc., 29 Pacella Park Drive, Randolph, Mass. 02368 Ill TABLE OF CONTENTS Page List of Plates v Foreword vi Editor's Preface vii Chapter I . Phylum PORIFERA 1 Glossary 1 Key 2 Checklist 6 II. Phylum CNIDARIA, Class Hydrozoa 8 Glossary 8 Key 10 Checklist 17 III. Phylum CNIDARIA, Class Scyphozoa 21 Key to attached Scyphozoa 21 Key to Scyphomedusae 21 IV. Phylum CNIDARIA, Class Anthozoa 25 Key 26 Checklist 26 V. Phylum CTENOPHORA, key and checklist 29 VI . Phylum PLATYHELMINTHES 30 Key to common Turbellarians 30 Checklist of Acoela, Rhabdocoela, and Alloeocoela 32 Checklist of Tricladida 36 Key to Polycladida 36 Checklist of Polycladida 37 VII. Phylum NEMERTEA (RHYNCHOCOELA) 40 Key 40 Checklist 43 VIII. Other Unsegmented Worms: Phylum ASCHELMINTHES 46 Phylum SIPUNCULOIDEA 46 IX. Phylum ANNELIDA 47 Classes Hirudinea, Oligochaeta, and Archiannelida 47 Polychaete Terminology 48 Key to Polychaete Families 51 Keys and checklists of Polychaete Species 63 X. Phylum ARTHROPODA, Subphylum Chelicerata 84 Xiphosurida 84 Key to Pycnogonida 84 Checklist of Pycnogonida 85 XI. Phylum ARTHROPODA, Lower Crustacea and Cirripedia 88 Cephalocarida, Branchiopoda, Ostracoda, Mystacocarida, Copepoda , Branchiura 88 Key to Cirripedia 89 Checklist of Cirripedia 91 Rhizocephala 92 iv Table of Contents XII. Phylum ARTHROPODA, Peracaridan Crustaceans 93 Key to Orders of Peracaridans 93 Part 1. Mysidacea 93 Key 94 Checklist 94 Part 2. Cumacea 98 Key 98 Checklist 99 Part 3. Isopoda and Tanaidacea 102 Key 102 Checklist 105 Part 4. Amphipoda 107 Keys to Suborders 112 Key to Families of Gammaridea 112 Checklist of Gammaridea 114 XIII. Phylum ARTHROPODA, Decapod and Stomatopod Crustaceans 117 Key to Decapods 117 Checklist of Decapods 121 Order Hoplocarida (Stomatopoda) 127 XIV. Phylum MOLLUSCA, Introduction 129 Outline classification 130 Glossary 131 Classes Amphineura and Cephalopoda 133 Key to Shelled Gastropoda 134 Checklist of Shelled Gastropoda 139 Key to Bivalvia 146 Checklist of Bivalvia 150 XV. Phylum MOLLUSCA, Shell-less Opisthobranchia 153 Key 154 Checklist 162 XVI. Phylum ENTOPROCTA 165 XVII. Phylum ECTOPROCTA 167 Glossary 167 Key 170 XVIII. Phylum ECHINODERMATA 188 Asteroidea, key 188 Ophiuroidea, key 188 Echinoidea, key 188 Holothuroidea, key 189 Asteroidea, checklist 189 Ophiuroidea, checklist 189 Echinoidea, checklist 192 Holothuroidea, checklist 192 XIX. Protochordates 193 Phylum HEMICHORDATA 193 Phylum CHORDATA, Subphylum Urochordata 193 Key to Ascideans 194 Checklist of Ascideans 198 Glossary of Common Names 200 Systematic Index (Genera and Higher Taxa) 202 V LIST OF PLATES Plate Pag e 1. Porifera 5 2. Hydrozoa 13 3. Scyphozoa and Anthozoa 23 4. Turbellaria (except Polycladida) 35 5. Polycladida, Nemertea, Sipunculoidea, Nectonema 45 6. Polychaete Setae 51 7. Polychaeta (1) and Archiannelida 53 8. Polychaeta (2) 55 9. Polychaeta (3) 57 10. Polychaeta (4) 59 11. Pycnogonida; Cirripedia 87 12. Mysidacea 97 13. Cumacea 101 14. Isopoda (1) and Tanaidacea 109 15. Isopoda (2) ; Hyperiidea and Caprellidea Ill 16. Decapod Crustacea (1) 123 17. Decapod Crustacea (2) and Hoplocarida 125 18. Mollusca (1) 143 19. Mollusca (2) 145 20. Shell-less Opisthobranchia (1) 157 21. Shell-less Opisthobranchia (2) 159 22. Shell-less Opisthobranchia (3) 161 23. Ectoprocta (1) and Entoprocta 181 24. Ectoprocta (2) 183 25. Ectoprocta (3) 185 26. Ectoprocta (4) 187 27. Echinodermata 191 28. Protochordates 197 FOREWORD Cape Cod juts eastward over the continental shelf as the flexed arm of Massa- chusetts, partly sheltered on its southern side by Monomoy, Nantucket, Martha's Vineyard, and the Elizabeth Islands. The Cape, islands, eastern shores of the state bordering the Cape, Cape Cod Bay, Nantucket Sound, Vineyard Sound, and Buzzards Bay constitute the Cape Cod Region. Glacial in origin, the Region is dotted by myriad small embayments and estuaries, and the clean tidal waters of the North Atlantic wash its shores a diverse ecologic setting accounting for the richness of the local marine biota, and for establishment of the Marine Biological Laboratory here in 1888. On September 1, 1962, the Marine Biological Laboratory inaugurated the Syste- matics -Ecology Program and embarked on a basic, year-round, long-term program of research and training in marine systematics and ecology. The Program has as one of its major objectives the gradual extension, in a broad sense and at a high lev- el of excellence, of systematic and ecologic knowledge of organisms in the estuar- ine and marine waters and bottoms of the Cape Cod Region. Early in the life of the Program we realized the lack of and recognized the urgent necessity for illustrated, referenced, indexed sets of keys and check lists of the commoner plants and animals of the Region for use by non-systematists in the Woods Hole scientific community and neighboring areas. A start on this task was provided in 1960 when Dr. Ralph I. Smith and others of the MBL Invertebrate Zoology Course staff assembled a small loose-leaf collection of keys then existing in the laboratory instructions of that course. These early keys had evolved over a period of years, and the authorship of some could not be determined. It was a happy occasion for us when Ralph Smith agreed to compile and edit this present publication. He arrived in Woods Hole early in the summer of 1963, worked indefatigably with us during that summer, then returned to Berkeley where he continued his labors, somehow sandwiched among his many duties at the Univer- sity. Now, some ten months later, the manuscript is ready for publication. We extend to Ralph our hearty thanks! A most sincere word of appreciation is also due collaborators without whose excellent cooperation and zeal the manuscript would never have been completed, and Mrs. San Lineaweaver for her patient and care- ful typing and correcting of the master copy. The preparation of this publica- tion •••as made possible by support of the Ford Foundation to the Systematics Di- vision of the Systematics-Ecology Program; it is a pleasure to acknowledge this aid. The first edition of the Invertebrate Keys is a beginning. We welcome sug- gestions, and look forward to producing revised editions as the invertebrates of the Region become better known. We are also planning to produce similar keys to other organisms of the Woods Hole Region as this becomes possible. Melbourne R. Carriker, Director Victor A. Zullo, Resident Systematist Systematics-Ecology Program Marine Biological Laboratory May, 1964 Woods Hole, Massachusetts EDITOR'S PREFACE vii This handbook of keys is an attempt to fill an obvious need at Woods Hole, the need for a general reference on marine invertebrates for the use of students and in- vestigators who want to know what is here and how to identify it. Relatively few present day biologists realize the difficulties involved in iden- tifying with certainty the myriad species of marine invertebrates. Some species are readily recognized by distinctive form or color, but in most cases the beginner will experience difficulty in making a positive identification, and in many instances the assistance of a specialist may be necessary. Keys are useful mainly in the identi- fication of common and obvious animals, or in making preliminary identification of less common animals (perhaps to family or genus) , or by indicating to the observant non-systematist that he has something out of the ordinary which should be referred to a specialist. The problem is akin to that of medical diagnosis; the alert zo- ologist, like the general practitioner, need feel no shame if he makes some identi- fications with confidence, but seeks consultation on others. The purpose of zoological classification is to arrange animals into groups on the basis of fundamental similarities. The completion of this task will presumably reveal evolutionary relationships, but the immediate objective of a set of keys is more utilitarian, that of identifying and providing the names of the local inverte- brate fauna as simply, accurately, and painlessly as possible. It cannot be too strongly emphasized that keys are shortcuts and often very misleading; their func- tion is merely to clear the way to an approximation, and identifications made by keys, if to be of scientific reliability, should be checked by reference to the original description or to recent monographs. A key is made to cover a selected list of species, and any species not one of that group will not "key out" or, worse yet, may key out as something which it is not, hence the need for a cross check in all cases of doubt. The terminology of systematists may be difficult for the non-systematist to grasp, owing to the independent evolution of descriptive jargon within the groups of specialists on different animal phyla. Therefore each key will when necessary be accompanied by a glossary and illustrations of the descriptive terms and by a brief statement of the characteristics used in the taxonomy of that particular group and how the student may locate and recognize them. The spicules of sponges, the se- tae of polychaetes, the ossicles of sea cucumbers, are of basic importance to sys- tematists in establishing the degrees of similarity which underlie classification; the problem of the biological role of these structures as functional parts of the animals concerned lies outside the immediate field of classification.