The Bivalvia

CONTENTS

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pp. v-vi

LIST OF PARTICIPANTS

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pp. vii-viii

INTRODUCTION

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pp. 1-2

The idea for a Symposium on the Bivalvia was discussed by the few students of this group present at the Eighth International Malacological Congress of Unitas Malacologica in Budapest in 1983. Following the decision to convene the next Congress in Edinburgh in 1986 I, as a retiring member of the UNITAS Council, formally...

ACKNOWLEDGEMENTS

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pp. 3-

I am grateful to the Council of Unitas Malacologia for agreeing to host this Symposium on the Bivalvia, in Edinburgh, at the Ninth Congress. I am also grateful to the President of Unitas, David Heppell, for help with the planning of the Symposium programme. Prof. R.G.B. Reid...

Photograph of Sir Charles Maurice Yonge

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pp. 4-

Sir Maurice Yonge: An appreciation

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pp. 5-7

It is entirely proper that the Ninth International Malacological Congress remembers Maurice Yonge and honours his name. Particularly so, because Edinburgh was his home. Few if any malacologists will not have heard of him and most of us will have read at least some part of his life's work. Very many will have had the pleasure of talking to or corresponding with him, ...

PLENARY Corals and their bivalve borers — the evolution of a symbiosis

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pp. 9-46

The evolution of hermatypic scleractinian coral reefs in the Mesozoic was an event which prevised important phases of molluscan adaptive radiation. The bivalve borers of coral skeletons constitute an excellent example of such a radiation. Representatives of six families are known to be coral borers: i.e., Lithophaginae...

Session A Evolution

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pp. 47-

THE EVOLUTION OF LIGAMENT SYSTEMS IN THE BIVALVIA

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pp. 49-72

In order to test models of the primary ligament and ligament evolution, ligament systems (arrays of ligaments and their shelly supports) were surveyed throughout the Bivalvia with particular attention to layer distinctions, ligament-layer / shell-layer association, and the ontogeny of ligament layers and supports. The results of this survey suggest that: (1), the...

STOMACH STRUCTURE, CLASSIFICATION AND EVOLUTION OF THE BIVALVIA

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pp. 73-82

The classification of the Bivalvia demands an understanding of the functional issues involved in the creation of a new, filter-feeding model, from the original deposit-feeding ancestors, and the subsequent adaptive radiation of this new model to habitats previously unavailable. This ...

FORM, FUNCTION AND PHYLOGENY OF BIVALVE MUCINS

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pp. 83-96

Many of the basic behavioural patterns found in bivalve molluscs are based on their abilities to produce mucins. These mucins play pivotal roles in activities as diverse as feeding, protection, shell formation, and dispersal. Mucins were almost certainly involved in incipient formation of calcified shells and likely were intimate components of presumed early cuticular ...

TAXONOMIC AND EVOLUTIONARY RELATIONSHIPS WITHIN THE GENUS MYTILUS

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pp. 97-110

This paper examines our current knowledge concerning the taxonomic and evolutionary relationships of species within the genus based on biochemical, physiological, cytological and morphometric data and stresses the importance of a multidisciplinary approach for the...

EVOLUTION OF CHEMICALLY-BORING MYTILIDAE (BIVALVIA)

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pp. 111-123

Most of the 34 species of Recent boring Mytilidae considered here use chemical means — a modified shell-resorbing ability, common in molluscs (Kiihnelt, 1930) — for boring: Botula (2 spp.), Fungiacava (1 sp.), Gregariella (2 spp.) and Lithophaga (25 spp.). Only certain Adula (3-4 spp.) bore mechanically. The fossil record of chemical borers, particularly ...

Session B: FEEDING AND DIGESTION

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pp. 125-

EVOLUTIONARY IMPLICATIONS OF SULPHIDE-OXIDIZING SYMBIOSES IN BIVALVES

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pp. 127-140

Sulphide-oxidizing symbioses between bivalves and intracellular ctenidial bacteria exist in Solemyoida, Lucinacea, Vesicomyidae and Mytilidae inhabiting sulphide-rich environments. In all of these groups except the Mytilidae the symbiosis has been the most radical evolutionary factor, affecting behaviour, ventilation and gill morphology. Labial palp...

GILL AND PALP MORPHOLOGY OF TELLINA TENUIS ANDT. FABULA IN RELATION TO FEEDING

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pp. 141-150

Internally as well as externally, there is little difference between Tellina tenuis and T.fabula. However there is a noticeable difference in the size of the gills and palps, and it has been suggested that this difference may lead to different feeding habits and hence to the species ...

PARTICLE SELECTION IN FILTER-FEEDING BIVALVE MOLLUSCS: A NEW TECHNIQUE ON AN OLD THEME*

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pp. 151-166

The efficiency of particle retention from algal suspensions, and its significance in the estimation of energetics of growth has been widely studied in bivalve molluscs. Whether filter-feeding organisms can (1) select; (2) preferentially ingest, and/or (3) preferentially digest suspended particles, is of major importance to our understanding of material flow...

FINE STRUCTURE OF THE DIGESTIVE TUBULES OF MERETRIX

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pp. 167-176

The fine structure of the digestive tubules of Meretrix meretrix has been studied by conventional transmission electron microscopy (CTEM). There are three types or phases of epithelial cells lining the tubules: (a) centrally placed flagellated basiphilic cells numbering...

FEEDING AND DIGESTION IN BIVALVE LARVAE

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pp. 177-194

During the larval life, three nutritional stages can be distinguished: endotrophy (or lecithotrophy), mixotrophy (or intermediate trophic stage) and exotrophy (or planktotrophy). In Mytilus edulis, for example, reared at 17-20�C, the first stage lasts 2 days, the second about...

Nutrition in Giant Clams

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pp. 195-210

Tridacnids derive their nutritional requirements from filter feeding, uptake of dissolved matter through their epidermis, and photosynthates (principally glucose) released by masses of the symbiontic zooxanthella Symbiodinium microadriaticum living within blood spaces of the hypertrophied siphons. Zooxanthellae also provide a holozoic food source for...

Session C: FUNCTIONAL MORPHOLOGY

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pp. 211-

THE FUNCTIONAL MORPHOLOGY OF THE ALIMENTARY CANAL OFDONAX VENUSTUS POLI AND D. SEMISTRIATUS POLI

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pp. 213-222

The functional morphology of the alimentary canal, particularly the stomach, of Donax venustus Poli and D. semistriatus Poli has been investigated. The stomach in both species belongs to type V as defined by Purchon (1960). There is a right caecum into which open ducts...

ULTRASTRUCTURAL STUDIES ON THE HEART-KIDNEY COMPLEX OF THREE SPECIES OF PROTOBRANCHBIVALVE MOLLUSCS

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pp. 223-236

Morphological and ultrastructural studies of the heart-kidney complex of the bivalve molluscs, Acila castrensis, Yoldia thraciaeformis and Y. limatula are reported. The heart in these species is tubular with marked differences in coloration between genera. Pericardial...

OSMOTIC EFFECTS ON THE FINE STRUCTURE OF THEKIDNEYS AND HEARTS OF SOME BIVALVES: THE SITEOF URINE FORMATION

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pp. 237-248

The fine structure of the hearts and kidneys of osmotically stressed marine Mytilus, Mercenaria and freshwater Anodonta were studied. Osmotic stresses were given to Mytilus and Mercenaria by keeping them in 50% sea water, and to Anodonta by keeping them in...

THE ADAPTIVE SIGNIFICANCE OF FOOTREVERSAL IN THE LIMOIDA

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pp. 249-264

The settlement and metamorphosis of pediveligers of one species belonging to the order Limoida are described. It is shown that the rotation of the foot through 180� which is characteristic of the order is probably concerned with balancing the shell and visceral mass on the foot during the crawling movements of the pediveliger. The pedal and byssal retractor...

Session D:EVOLUTION 2 / ECOLOGY

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pp. 265-

FUNCTIONAL SIGNIFICANCE OF THE PEDIVELIGER IN BIVALVE DEVELOPMENT

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pp. 267-282

The swimming-crawling, bivalve-shelled pediveliger is a critical, little-studied, transitional stage between planktonic and benthic existence in most bivalve molluscs. A review of the literature indicates that the pediveliger stage occurs in three subclasses, 31 families, and 66...

AN INTRODUCTION TO THE RAZOR SHELLS (BIVALVIA: SOLENACEA)

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pp. 283-312

The Solenacea (Solenidae with Solen and Solena and Pharidae with Ensis, Phaxas, Cultellus, Pharus, Siliqua, Sinonovacula, Pharella and Orbicularia) are a commercially important soft bottom infaunal marine bivalve group. It is proposed that Pharus, hitherto grouped in the Tellinacea, be placed in the Solenacea

SOLECURTUS STRIGILATUS:A JET-PROPELLED BURROWING BIVALVE

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pp. 313-320

The digging cycle of Solecurtus strigilatus involves five phases, culminating in the powerful injection of a narrow jet of water into the sediment around the active foot. The animal burrows deeply into the sea floor and avoids capture by rapid escape burrowing to over 50 cm deep....

SPATIAL GRADIENTS IN PREDATION PRESSURE AND THEIR INFLUENCE ON THE DYNAMICS OFTWO LITTORAL BIVALVE POPULATIONS

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pp. 321-332

The interactive roles of predation, competition and tidal elevation in structuring populations of two contrasting bivalve species, the cockle Cerastoderma edule and the mussel Choromytilus meridionalis, were compared. Cockles settled at relatively low densities throughout...

HABITS AND MORPHOLOGICAL ADAPTATIONS OFMYTILIDS (MOLLUSCA: BIVALVIA) FROM COASTAL ANDREEFAL ENVIRONMENTS IN SOUTHWE

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pp. 333-344

The Tulear reef complex was chosen as a model for this work because of its high biotope diversity, its mytilid richness, and more generally because of the large background knowledge about its faunistic assemblages and environments. Distribution through the reef complex, habits, shell shape and ornamentation of 13 representative species are analysed on the...

APPENDIX A chronological list of publications on the Bivalvia by CM. Yonge

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pp. 345-346