Mitogenomic trees for Bivalvia have proved problematic in the past, but several highly divergent lineages were missing from these analyses and increased representation of these groups may yet improve resolution. Here, we add seven new sequences from the Anomalodesmata and one unidentified semelid species (Bryopa lata, Euciroa cf. queenslandica, Laternula elliptica, Laternula truncata, Lyonsia norwegica, Myadora brevis, Tropidomya abbreviata, "Abra" sp.). We show that relationships in a mitogenomic tree for the Class are improved by the addition of seven anomalodesmatans from this highly divergent clade, but are still not completely consistent with relationships recovered in studies of nuclear genes. We suggest that some anomalous relationships (for instance the non-monophyly of Bivalvia) may be partially explained by compositional heterogeneity in the mitogenome and suggest that the addition of more taxa may help resolve both this effect and possible instances of long branch attraction. We also identify several curious features about anomalodesmatan mitogenomes. For example, many protein-coding gene boundaries are poorly defined in marine bivalves, but particularly so in anomalodesmatans, primarily due to non-conserved boundary sequences. The use of transcriptomic and genomic data together enabled better definition of gene boundaries, the identification of possible pseudogenes and suggests that most genes are translated monocistronically, which contrasts with many other studies. We also identified a possible case of gene duplication of ND5 in Myadora brevis (Myochamidae). Mitogenome size in the Anomalodesmata ranges from very small compact molecules, with the smallest for Laternula elliptica (Laternulidae) only 14,622bp, to Bryopa lata (Clavagellidae) which is at least 31,969bp long and may be >40,000bp. Finally, sampled species show a high degree of sequence divergence and variable gene order, although intraspecific variation in Laternula elliptica is very low.

Whale remains (a left and right mandible, scapula, humerus and fragmentary radius and ulna as well as parts of the cranium and rostrum) belonging to a probable humpback whale (Megaptera cf. novaeangliae) were found in the well-described sabkha sequence exposed in the Musaffah Industrial Channel, Abu Dhabi, United Arab Emirates. More precisely, the whale remains were found in a series of sediments representing a range of lagoonal facies. The sediments surrounding the whale bones were age-dated at approximately 5200 14C yrsBP and are therefore interpreted to correspond to the previously documented late Flandrian sea-level peak, preceding a fall in sea-level which culminated in the supratidal sabkha overprint of the carbonates. Associated with the whale remains is an assemblage of molluscs, foraminifera and ostracods. Together with the inferred presence of sea grass and algae, these facies are interpreted to indicate a very shallow subtidal to intertidal lagoonal environment. Cirripede remains found associated with the skeleton were identified as those of the whale barnacle Coronula diadema and hence had their origins with the whale. Significantly, the low species diversity of microfossils suggests that higher salinities existed in the mid-Holocene lagoon than are present in modern counterparts. This is here inferred to be related to the onset of continental aridity in Arabia during the mid-Holocene.

Live-collected specimens of the lucinid bivalve, Rasta lamyi, hitherto known only from dead shells, possess long periostracal pipes arranged radially around the valve margins. The bivalves were found in the northern Red Sea, mostly in muddy sand, with sparse seagrass cover, at depths between 10-48 in. The periostracal pipes and general anatomy are similar to those of the type species R. thiophila front Western Australia. Although the morphological features are unusual, a molecular phylogenetic analysis demonstrates that R. lamyi groups within a major clade of shallow water lucinids.

The bivalve superfamily Lucinoidea is usually considered to comprise six separate families: Lucinidae, Thyasiridae, Ungulinidae, Fimbriidae, Mactromyidae and Cyrenoididae. Chemoautotrophic chemosymbiosis with sulphide-oxidizing bacteria is present in all studied species of Lucinidae, Fimbriidae and many, but not all, Thyasiridae. However, it is absent from Ungulinidae. The Mactromyidae are likely to be an entirely fossil group with doubtful affinities with Lucinoidea. The Cyrenoididae are poorly investigated, but anatomical features suggest they are unrelated to lucinoids. To investigate phylogenetic relationships within the Lucinoidea and test hypotheses concerning the evolution of the chemosymbiosis, a molecular study was made using sequences of 18S and 28S rRNA genes. The study incorporated species of Ungulinidae (two genera, two species), Thyasiridae (three species), Fimbriidae (one species) and many Lucinidae (31 species, 19 genera) as well as a range of outgroups representing major groups of heterodont and palaeoheterodont bivalves. The results demonstrate that the monophyly of the Lucinoidea is not supported. The Ungulinidae and Thyasiridae are unrelated to the Lucinidae. Ungulina and Diplodonta of the Ungulinidae group with a clade comprising Veneroidea, Arcticoidea and Mactroidea. The three Thyasira species analysed form a monophyletic branch in a basal position among the heterodont bivalves. The only member of the Fimbriidae examined, Fimbria fimbriata, groups within the Lucinidae and separation as a family is not supported. The Lucinidae form a monophyletic group within which several distinct and well-supported clades and lineages are recognized: the Myrtea clade, the 'Anodontia' clade, Fimbria lineage, Phacoides pectinatus lineage, and two clades comprising all other lucinids. The implication of non-monophyly of the superfamily Lucinoidea is that Thyasiridae represent an independent acquisition of bacterial chemosymbiosis and this is reflected in major morphological differences from the Lucinidae.

Bathyaustriella thionipta, a new species from water depths of 480-500 in on the Macauley Caldera, Kermadec Ridge, is the first record of a member of the chemoautotrophic bivalve family Lucinidae from an active hydrothermal vent. The new species and genus is morphologically similar to the shallow-water, mangrove mud-inhabiting Austriella corrugata from the central Indo-West Pacific region. Sequences of 18S and 28S rRNA genes confirm its position close to Austriella within a clade of shallow-water lucinids. Features of B. thionipta include the extremely large gill, the vacuolated foot, two coiled, lobate structures arising from the anterior body wall and a very thick periostracum. Its probable close relationship to shallow-water lucinids lends support to an hypothesis proposing the onshore to offshore derivation of deep-sea and vent faunas.

A new genus Lamellolucina is proposed for a group of Indo-West Pacific lucinid bivalves with prominent commarginal lamellae often confused under the name Lucina dentifera Jonas. The genus comprises seven species, four of these are newly described from the Indo-Pacific and a single species L. revrei Nickles is known from West Africa. The type species L. pilbara n.sp. appears to be endemic to northwestern Australia. L. gemma Reeve is recorded from China, Philippines and Queensland, L. jawa n.sp. is described from Madura, Indonesia. L. trisulcata n.sp. ranges from southern India to Indonesia and L. oliveri n.sp. is known from Arabian Sea and Gulf of Oman. L. dentifera appears to be restricted to the Red Sea and Gulf of Aden.

Gastropods are one of the most diverse groups of animals, encompassing a wide variety of life habits from deposit feeding to hunting predation. They are abundant in most marine and many non-marine habitats and because of the relatively robust shells have an excellent fossil record. Because of their diversity and abundance as fossils, gastropods have been widely used in palaeobiogeographical and palaeoenvironmental studies, and some of the best examples of the influence of global events on the marine fauna involve these molluscs.

Recent years have seen a growing interest in the direct and indirect roles of organisms, and more explicitly of organic matter, in the crystallization of minerals in sediments. Two bivalve genera form extensive biofilms that are apparently responsible for the growth of a variety of isolated crystals together with a marine cement. Granicorium indutum and Samarangia quadrangularis are infaunal species that cover their shells with a cemented coating of sand, sculpted to mimic the surface ornament typical of many bivalves. Granicorium has an exceptionally mobile mantle margin that produces large volumes of mucus, harboring a diverse microbial community. The sand grains surrounding both species are initially bound by a biofilm that provides structural integrity but also acts, like others, as a template for the crystallization of a variety of carbonate polymorphs, These include varied prismatic crystals, rice-grain and wheatsheaf forms and, more importantly, large volumes of acicular crystals indistinguishable from typical marine cements. The distribution of these crystals is related to positions accessible to the mantle of the animal and in Samarangia appears to result from the active emplacement of grains and mucus several times a year. Summing the evidence, it seems that these species are responsible not only for the biomineralization involved in the formation of their shells but also for crystallization mediated through biofilms and for the generation of cements that are morphologically indistinguishable from typical marine cements. The boundaries between these three strategies may be closer than we think.

All Lucinidae species studied so far possess sulphide-oxidizing. chemosymbiotic bacteria housed in bacteriocytes of gill filaments. The ecology, functional anatomy and evolution of the Lucinidae must be considered in relation to this symbiosis. The ctenidia have been extensively studied but other anatomical structures peculiar to lucinids have received much less attention. Reviewed are the morphological diversity of living lucinids, highlighting features of their anatomy including ctenidia, pallial apertures, anterior adductor muscle, pallial blood vessel and mantle gills. The latter are much more complex than previously understood and are here redescribed, They comprise Folded structures located near the anterior adductor muscle in Codakia, Phacoides and Lucina, and on the septum of Anodontin. These are interpreted as secondary respiratory surfaces, their location enabling the separation of the anterior inflow of oxygenated water from sulphide-containing water. The latter is released from the sediment by the probing activities of the highly extensible foot and is pumped over the gill through the pedal gape and perhaps also via the exhalant tube. The shell Features of Ilionia from the Silurian Period suggests that the lucinid chemosymbiosis is an ancient association.

Bivalves have been important members of marine communities since the early Palaeozoic, in terms of both their numerical abundance and diversity. They are particularly prevalent in shallow shelf sediments, but they have also conquered the intertidal zone as well as the deep sea, where they are successful predators and key components of some vent communities. They have also invaded freshwater systems a number of times, where today they are important (and costly) foulers. In terms of general community structure, bivalves are important as prey items for a range of different predatory groups, and as major space occupiers, particularly on hard substrata where space may be limited. The abundance and diversity of both Recent and fossil bivalves have made them attractive subjects for both zoologists and palaeontologists, and both disciplines have contributed to the present system of classification and the understanding of their phylogenetic relationships. However, somewhat inevitably, the focus of the two groups has been rather different, with zoologists concentrating on anatomical characters such as those associated with the gills and stomach, whilst palaeontologists have necessarily dwelt on hard-part characters such as dentition and shell microstructure. It is becoming increasingly clear, however, that convergence and parallelism is rife within the class and more integrated approaches are necessary to unravel these. The last major attempt to integrate the palaeontological and zoological approaches to bivalve evolution was more than 20 years ago, at the Royal Society of London meeting in 1977. The resulting volume of the Philosophical Transactions of the Royal Society

Understanding patterns of marine biodiversity is a complex and challenging subject which can be approached in many different ways and at many levels. Recently, new approaches, using phylogenetic methods have been used to look at the deeper structure of the diversification process. These methods are used to examine diversification in three ecologically important groups of predatory Caenogastropoda. New phylogenetic hypotheses, both morphological and molecular, provide the framework to test ideas concerning the origin and evolution of different feeding behaviours and dietary specializations. For the Tonnoidea, the acquisition of enlarged salivary glands capable of secreting sulphuric acid probably allowed the specialization into echinoderm feeding. The Muricidae possess a battery of adaptations for gaining access to heavily armoured prey. However, only the accessory boring organ in the foot is an autapomorphy of the family, toxic secretions from the hypobranchial gland and accessory salivary glands are known in several other neogastropod families and cannot be considered as key adaptations. In the Conoidea, hypodermic radular teeth have evolved independently in at least six different clades, whilst the venom apparatus is present in most species, including the least-derived. The crucial adaptation associated with a massive diversification within the Conoidea is the evolution of the radular caecum, which is analogous to an archer's quiver, whereby the harpoon-like radular teeth can be stored ready for use.

Presence of a toxin in the salivary glands of the marine snail Cymatium intermedius that targets nicotinic acetylcholine receptors. Toxicon 36, 25-29, 1998.-We present evidence of a neurotoxin from the salivary glands of Cymatium intermedius that displays acetylcholine-like effects on vertebrate (mouse ileum) and invertebrate (molluscan smooth muscle; molluscan heart; leech body wall) tissues. These effects were completely blocked by (+)-tubocurarine (10-100 muM) but not by atropine (up to 200 muM) suggesting that the toxin targets nicotinic-like acetylcholine receptors. This affirms the proposal that this genus may overcome their prey with a paralytic secretion.