Channel Island Marine Molluscs
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Channel Island Marine Molluscs An Illustrated Guide to the Seashells of Jersey, Guernsey, Alderney, Sark and Herm Paul Chambers Channel Island Marine Molluscs - An Illustrated Guide to the Seashells of Jersey, Guernsey, Alderney, Sark and Herm - First published in Great Britain in 2008 by Charonia Media www.charonia.co.uk [email protected] Dedicated to the memory of John Perry © Paul Chambers, 2008 The author asserts his moral right to be identified as the Author of this work in accordance with the Copyright, Designs and Patents Act, 1988. All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical including photocopying, recording or by any information storage and retrieval system, without permission from the Publisher. Typeset by the Author. Printed and bound by Lightning Source UK Ltd. ISBN 978 0 9560655 0 6 Contents Introduction 5 1 - The Channel Islands 7 Marine Ecology 8 2 - A Brief History of Channel Island Conchology 13 3 - Channel Island Seas Shells: Some Observations 19 Diversity 19 Channel Island Species 20 Chronological Observations 27 Channel Island First Records 33 Problematic Records 34 4 - Collection, Preservation and Identification Techniques 37 5 - A List of Species 41 Taxonomy 41 Scientific Name 42 Synonyms 42 Descriptions and Illustrations 43 Habitat 44 Distribution of Species 44 Reports of Individual Species 45 List of Abbreviations 47 PHYLUM MOLLUSCA 49 CLASS CAUDOFOVEATA 50 CLASS SOLENOGASTRES 50 ORDER NEOMENIAMORPHA 50 CLASS MONOPLACOPHORA 51 CLASS POLYPLACOPHORA (chitons) 51 ORDER NEOLORICATA 52 CLASS GASTROPODA (gastropods, snails) 57 SUBCLASS PROSOBRANCHIA (sea snails) 58 ORDER ARCHAEOGASTROPODA (ormers, top shells, etc.) 58 ORDER PATELLOGASTROPODA (limpets) 74 ORDER MESOGASTROPODA (winkles, tritons, etc.) 79 ORDER NEOGASTROPODA (whelks) 129 ORDER HETEROSTROPHA (pyramid shells) 146 3 Channel Island Marine Molluscs SUBCLASS OPISTHOBRANCHIA 162 ORDER CEPHALASPIDEA (headshield slugs) 162 ORDER SACOGLOSSA 171 ORDER ANASPIDEA (sea hares) 173 ORDER NOTASPIDEA 176 ORDER THECOSOMATA (sea butterflies) 178 ORDER GYMNOSOMATA 179 ORDER NUDIBRANCHIA (sea slugs) 179 SUBCLASS PULMONATA (air breathing gastropods/snails) 195 ORDER SYSTELLOMMATOPHORA 195 ORDER ACTOPHILA 196 CLASS SCAPHOPODA (tusk shells) 198 ORDER DENTALIIDA 198 CLASS PELECYPODA (bivalves, clams) 200 ORDER NUCULOIDA (nut shells) 201 ORDER ARCOIDA (ark shells, dog cockles) 202 ORDER MYTILOIDA (mussels) 207 ORDER PTERIOIDA (fan mussels) 213 ORDER LIMOIDA (file shells) 215 ORDER OSTREOIDA (oysters, scallops) 217 ORDER VENEROIDA (venus shells, etc.) 224 ORDER MYOIDA (gape shells) 271 ORDER PHOLADOMYOIDA (boring molluscs, etc.) 282 CLASS CEPHALOPODA (cephalopods) 286 ORDER SEPIOIDEA (cuttlefish) 286 ORDER TEUTHOIDEA (squid) 288 ORDER OCTOPODA (octopuses) 289 6 - Further Work 294 Acknowledgements 295 Appendix One: Channel Island Brachiopods 296 Appendix Two: A Glossary of Terms 299 Bibliography 302 Indexes 312 Additional Species 322 4 Introduction he Channel Islands are located on the French side of the English Chan- Tnel and represent the southern boundary of the British Isles. As well as being admired for their beauty and Anglo-French culture, the Channel Islands have a flora and fauna that is subtly different to that of the British mainland. Many of the islands’ plants and animals do not occur (or are rarer) in the United Kingdom; this is particularly true of the marine molluscs (sometimes referred to as seashells) which are not only noticeably diverse but also contain several species whose northerly limit is reached at the Channel Islands. The uniqueness and diversity of Channel Island molluscs has been recognised for over two centuries but until now there not been a comprehensive survey of all the islands’ marine Mollusca and so estimates as to how many species may be present has varied considerably. This book provides a list of all the marine mollusc species that have been reported to occur in Channel Island territorial waters. Using 118 publications from the present day back to the sixteenth century, the author has collected approximately 4,000 reports of individual mollusc species from Jersey, Guern- sey, Alderney, Sark, Herm and the lesser islands, islets and uninhabited reefs that make up the Channel Islands. Each report has been checked, updated and collated into a single list which, for the first time, provides comprehensive information on the reported occurrence, distribution, habitat and taxonomy for all the known Channel Island marine mollusc species. Illustrations and a brief description have also been included to aid the reader with the identifica- tion of specimens. This survey reveals that a total of 479 marine mollusc species have been reported from the Channel Islands, of which 39 are proba- bly misidentifications or represent exotic specimens brought into the region from elsewhere. It should be noted that this is an amateur work, but even so it will hopefully be a useful and relatively inexpensive guide for amateur beachcombers as well perhaps being of some interest to professional zoologists. The author will gratefully accept all criticisms, corrections, additions and comments. Dr. Paul Chambers www.paulchambers.eu 5 Channel Island Marine Molluscs Figure 1 - Map of the British Isles showing the geographical position of the Channel Islands. 6 1 - The Channel Islands he Channel Islands are a collection of islands, islets and offshore reefs Ton the southern side of the English Channel, adjacent to the Normandy and Brittany coasts. The islands are geographically close to France, being at their nearest points (both of which are on Alderney) ninety-seven kilometres from England but only sixteen kilometres from the Cherbourg peninsular (Fig. 1). As such, the Channel Islands represent the British Isles’ most southerly territory and enjoy a temperate climate of mild winters and cool summers supplemented with around 1,900 hours of sunshine a year (Guernsey or Jersey are often the sunniest places in Britain). This geographical positioning greatly benefits the local tourist and agricultural industries, but it has also allowed the islands to receive a number of animal and plant species from continental Europe that do not occur (or are rare) on the northern side of the English Channel. Such species are to be found in most of the islands’ terrestrial and aquatic flora and fauna, including the marine Mollusca. As well as being geographically separate from the United Kingdom, the Channel Islands are also politically independent. The islands are formed into two self-governing Bailiwicks: Jersey, including Les Écréhous and Les Min- quiers; and Guernsey, which includes Alderney, Sark, Herm and several lesser islands (these are sometimes referred to as the Sarnian Islands). This unusual situation stems from the Channel Islands having once been part of the Duchy of Normandy which became English territory in 1066 but was lost again by King John in 1204. Rather than become French, the Channel Islands chose to remain with the English Crown and were afterwards valued for their strategic maritime position. The islands’ Norman heritage is reflected in many aspects of their culture and legislature, as well as in place names and local languages which are derived from ancient Norman-French. The Channel Islands have been self-governing for over eight centuries, and only rely upon the British Parliament in matters that concern defence, citizen- ship and diplomacy. Both Jersey and Guernsey have elected parliaments, known as the States, which set their own laws and taxes. Channel Islanders are British citizens but the islands themselves are not part of the European Union, although they do fall within the Customs Territory of the European Communi- ty. Their economies were once reliant on tourism, shipping, agriculture and fisheries, but in recent decades the islands have transformed themselves into offshore finance centres. The success of this has attracted many people to Jersey and Guernsey both to work and live, placing pressure on limited resources such as housing, transport, water and social services. There are restrictions governing an individual’s right to live and work within the islands but even so, over half the current population are recent immigrants, usually from Britain but with a sizeable input from France and Portugal. 7 Channel Island Marine Molluscs Marine Ecology Those living on the Channel Islands have an enduring bond with the sea. Islanders are keen on watersports, beach leisure and fishing, and are justly proud of their unpolluted seas and clean beaches. Great lengths are taken to avoid unnecessary environmental damage to the marine realm through the careful monitoring of littering, water-borne pollution and over-fishing. The Bay of St Malo, which includes the islands, is noted for its large tidal range which, on Jersey, can exceed twelve metres. Low water on large spring tides exposes kilometres of beach giving naturalists and fishermen the chance to explore the islands’ unique coastline. The islands possess a coastline which is notably varied and includes long sandy beaches, rocky shores, muddy harbours and steep cliffs which drop directly into deep water. Most seashore types are represented with the excep- tion of the lower salinity waters and wide mudflats that are commonly associ- ated with river estuaries (the islands have no rivers although small brackish ponds and muddy coves and harbours do exist). Western facing coasts are generally more exposed to the prevailing