Larvae of Decapod Crustacea
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THE RAY SOCIETY INSTITUTED MDCCCXLIV This volume (No. 129 of the Series) is issued to the Subscribers to the RAY SOCIKTY for the Year 1941. LONDON MCMXL11 TO MY WIFE LARVAE OF DECAPOD CRUSTACEA ROBERT GURNEY, M.A., D.Sc, F.L.S. LONDON PRINTED FOR THE RAY SOCIETY SOLD BY BERNARD QUARITCH, LTD. 11, GRAFTON STBEET, NEW BOND STBBBT, LONDON, W. 1 1942 Made and printed in Ortat Britain by Adlard * Son, Ltd., at their worts, Bartholomew Prut, Dorking. PREFACE I AM already indebted to the Ray Society for under taking the publication of my Bibliography, and it is a great satisfaction to me that the Committee has now accepted the remainder of the work on Decapod Larvae which I had not dared to hope would ever be published. The general part is as I originally planned it, but the descriptive part has been much curtailed. I have tried to give all the essential information, with figures of typical species in each family, in most of the groups. Where a family contains such diverse types as are found in Hippolytidae, for example, such treatment is not very satisfactory, but the examples given will probably be found adequate. While I have aimed at describing larvae of each family this has not been done in the Brachyura, since there are so many families and the differences between them are, for the most part, very small. When possible a summary of family characters has been given ; but such summaries may be unreliable, or inadequate, owing to the many reservations which have to be made. I make no apology for the fact that no exactly uni form system has been followed. The variety in treat ment arises partly from the nature of the material, partly from the differences in systematic interest attaching to the groups, and partly from personal caprice. The illustrations are, with very few exceptions, original, since I have made a point of first-hand acquaint ance with the facts. To each family is appended reference to one or more works dealing with it, generally the most recent; but further references will in most cases be found in the bibliography previously published. The list of publications includes omissions from the Bibliography, papers which have appeared since, and others, not necessarily directly concerned with Decapod larvae, which are referred to in the present volume. I am indebted to a reviewer, to Miss Gordon and to Miss Lebour for drawing my attention to some omissions, but I have little doubt there are others still to find. VI PREFACE For instance, I have not been at pains to include all references to translations or abstracts, and in some cases these contain original notes which should be recorded. I confess that I did not spend much time in searching for references to development in ancient literature, and my attention has been drawn to the omission of Leeu- wenhoek's description of the Prezoea of Crangon in 1686. I have not been able to see the original publica tion, but presume that the translation to which reference is given is correct, and the figure exactly copied. The observation unfortunately does no credit to Leeuwen- hoek's reputation, and might better have been for gotten. He evidently had no suspicion that the shrimp has a larval phase. I am more concerned to realize that I have omitted some recent papers of undoubted value. When such papers have not been included in the Zoological Record or reprints have not been received, they have, not unnaturally, escaped my notice. I would like to express my gratitude to Dr. Crossland and Dr. Wheeler, directors of the Ghardaqa and the Bermuda Biological Stations respectively, and still more to Dr. Allen during his long directorship at Plymouth. It is now nearly forty years since I first paid attention to these larvae at Plymouth, and I treasure the memory of many visits and much kindness from all the staff. To Miss Lebour I owe a great debt for her ungrudged assistance at every point, whether in gift of specimens or advice, and particularly for her encouragement in going on with this work, and for reading and improving it as it proceeded. ROBERT GURNEY. Boars Hill, Oxford ; Jan., 1941. CONTENTS PART I.—GENERAL. PAGE 1. Historical 3 2. Classification ....... 10 3. Bearing of the larval phase upon classification . 12 4. Larvae ........ 17 5. Larval stages ...... 30 6. Names in use for larval stages 36 7. List of larval genera, with their probable identificatior l 37 8. Nauplius ....... 39 9. Protozoea ....... 43 10. Embryonic cuticle ...... 51 11. Abbreviated development .... 54 12. Reproduction of Deeapoda of land and fresh water 61 13. Poecilogony ....... 64 14. Dimorphism ....... 67 15. Artificial rearing ...... 68 16. Giant larvae ....... 71 17. Chromatophores and coloration 75 18. Rate of- growth ...... 81 19. Mutation in Caridea of the family Atyidae 83 20. Locomotion of larvae ..... 88 21. Influence of light upon movement . 91 22. Distribution ....... 96 23. Eggs and egg-bearing ..... 102 24. Temporary loss and replacement of appendages 106 25. Frontal organ ...... 108 26. Dorsal organ . 110 27. Carapace 112 28. Abdomen 114 29. Telson . 116 30. Eye 123 31. Antennule J125 32. Antenna J26 33. Mandible 128 34. MaxiUule 131 35. Maxilla 133 36. Maxillipedes 136 37. Legs 141 38. GUIs 143 39. Pleopods 152 40. Internal anatomy 157 41. Development of Euphausiacea 157 42. Development of Stc>matopod a .... 160 PART II.—DESCRIPTIVE. DECAPODA. EUPHAUSIACEA . EUDECAPODA MACRURA NATANTIA. PENAEIDEA ...... Penaeidae ...... Sergestidae ...... CABIDEA ....... Hoplophoridae . Disciadidae ...... Rhynchocinetidae . Atyidae ...... Pasiphaeidae ...... Pandalidae ...... Hippolytidae ... Processidae ...... Alpheidae ...... Palaemonidae . Crangonidae ...... Amphionidae . MACRURA REFIANTIA. NEFHBOPSIDEA ...... EKYONIDEA ....... SCYLLABIDEA ...... STENOPIDEA .-. THALASSINII>EA ...... Axiidae ...... Callianassidae . Upogebiidae ...... Laomediidae ...... ANOMURA. GALATHEJDEA ...... Aegleida-e ...... Galatheidae ...... Porcellanidae ..... PAGUBIDEA ...... Paguridac ...... Lithodidae ...... HIPPIDEA ....... DBOMIACEA ........ BRACHYURA. GYMNOPLEUBA ...... BEACHYBHYNCHA ...... OXYEHYNCHA ...... OXYSTOMATA ...... PART I.-GENERAL i LARVAE OF DECAPOD CRUSTACEA HISTORICAL. The first Decapod larva described is.Cancer germanus Linnaeus (1767). This was, no doubt, a Megalopa, and Williamson (1915, p. 566) suggests that it may have been th&,same as Megalopa armata, Leach. In 1775 Slabber described a Zoea, which may well have been that of Carcinus maenas, under the name of Monoculus laurus, and a summary of his observations is given by Williamson (1-915, p. 319), with reproductions of his figures. Slabber claimed "to have seen the transforma tion of his M. taurus into. a completely different form which can be recognized as the larva of Callianassa. He also gave a figure of a Megalopa, and it may be supposed that he did actually witness the moult of the Zoea to the post-larVal Crab, and mixed up bis drawings. Williamson however points out that the Zoea figured is in too early a stage for such an explanation to be possible. The name Zoea was given by Bosc in 1802 to the early larva, of a crab, and Megalopa by Leach to 1813 to the post-larval stage, various species being described as belonging to these supposedly adult genera. Another such larval genus is Monolepis, Say (1817); but this probalby belonged to the Hippidea. It is worth noting that, in 1778,* De Geer had actually witnessed the hatching of the Naupljus of * Leeuwenhoek, in a letter dated .^Oct. 16, 1690, described a series of observations on the hatching of the eggs of Cyclops. He noted that the ' animalcules " hatched from the eggs, differed entirely from the parent, so that it might be claimed that he was the first to record metamorphosis in Crustacea. His observations on the unhatched larva of Crangon were illustrated by two very crude figures, and showed no appreciation of the difference between larva and adult. 4 LARVAE OF DECAPOD CRUSTACEA Cyclops, and had commented upon the remarkable dissimilarity between young and adult. His figure of the Nauplius is excellent, and much better than those given by Mtiller in 1785 for his genera Nauplius and Amymone. The systematic position of these larval genera was naturally a matter of peculiar difficulty. The different views taken were summarized by H. Milne-Edwards (1837, II, p. 431), who himself placed Zoea in an appen dix as " Decapodes douteux." Desmarest (1825) had treated the species as Branchiopods, as Bosc had done, while Lamarck, although dealing with them as Branchio pods, suggested that they might belong to the Schizopods. Leach placed them among the Podophthalmata, but Milne-Edwards observed that his reasons for doing so were not clear, and had not convinced other zoologists. In 1787 Cavolini had published a figure (pi. ii, fig. 9) showing quite clearly the general form of the Brachy- uran Zoea at the moment before hatching, but to Vaughan Thompson (1828, etc.) belongs the credit for the definite proof that most Decapoda leave the egg in a form totally different from that of the adult. His first announcement that Cancer pagurus hatches as a Zoea, with his claim that all Zoeas are larval Brachyura, and that metamorphosis is the rule among Decapoda, were not made in a form that carried conviction, and it must be admitted that he did not present his case as well as he might have done. Westwood (1835, 1836) strongly contested the validity of Thompson's conclusions, rely ing upon the indisputable fact that the Crayfish and also some Crabs do actually hatch in a form closely resembling the adult.* Westwood based his obser vations upon the examination of the abdomen of a " West Indian Land Crab " to which newly-hatched * The level of argument on the subject may be judged from two quotations. Thompson (1831, p. 383) says that, if one case of metamorphosis is proved, " we may safely infer from analogy, as far as regards the particular tribe alluded to, that it is general." And Westwood (1835, p.