Bivalve Family Research Articles

Epifaunal aggregations of Vesicomyidae on the continental slope off Louisiana

Two species of the bivalve family Vesicomyidae living at a depth of 940 m in the central Gulf of Mexico were photographed, counted and measured. These species, which are related to bivalves in chemmouatotrophic communities in the Gulf of Mexico and at hydrothermal vents in the Pacific Ocean, occurred here in two apparently distinct aggregations clearly visible on the sea floor surface. Living vesicomyids were generally found amid a scatter of dead shells and occurred in densities of 0.5–9.6 individuals per m 2. Distribution of living individuals within the aggregations was patchy. Living clams appear to plow actively through a substrate of silty clay, leaving behind distinctive, curving furrows up to 205 cm in length. Estimates of density, size distribution and spatial distribution provide a basis for detection of change in the aggregations over time and for comparison with similar aggregations.

Siphon structure and prey capture as a guide to affinities in the abyssal septibranch Anomalodesmat a (Bivalvia)

Abstract Four families of predatory abyssal anomalodesmatan bivalves are recognized - the Parilimyidae, Verticordiidae, Poromyidae, and Cuspidariidae. Only in Cuspidaria has prey capture been observed. The prey capture mechanisms in representatives of other families have been inferred by interpretation of either living (Poromya) or dead material (Parilimyidae, Verticordiidae). In all those species examined to date, prey capture is by a raptorial inhalant siphon that is dramatically extended as a result of hydraulic pressure changes within the mantle cavity causing a corresponding translocation of blood from a pallial reservoir into it. The siphon, with captured prey, is returned to the body by pallial retractor muscles. Siphon structure and prey capture mechanisms in the Parilimyidae, Poromyidae and Cuspidariidae are reviewed. For the Verticordiidae a different method of prey capture has hitherto been proposed, all species supposedly grasping their prey with sticky siphonal tentacles. A study of Lyonsiella formosa (JEFFREYS), however. cast doubt on this interpretation and concluded that prey capture was by the eversion of a raptorial inhalant siphon much as in Poromya. This study reinvestigates siphon structure and postulates prey-capture mechanisms for four genera and species of verticordiids, i.e. Verticordia, Policordia, Halicardia, and Lyonsiella. All feed in essentially the same way. Large siphonal tentacles are not sticky but sensory. Ciliary sense organs, essentially similar to those described for Poromya and Cuspidaria are receptive to prey movements. Prey capture is by eversion of an, albeit short, inhalant siphon. Prey thus has to approach the bivalve very closely, unlike other septibranchs which can effect capture at a distance. Siphonal eversion is by pumping of blood from a pallial lacunal system; retraction is by pallial retractors modified in species of Lyonsiella into discrete taenioid muscles. On the basis of this study, a better picture of phylogenetic affinities in these related bivalves is possible. The stem group seems to be represented by verticordiids and parilimyids. Most verticordiids are of relatively simple plan and their siphonal prey-capture mechanism comparatively unspecialized. Parilimyids and Lyonsiella, however, have a pair of taenioid muscles, enhancing the efficiency of siphonal retraction. Lyonsiella formosa (at least) feeds like poromyids, suggesting a phylogenetic link; the latter, however, being the more morphologically specialized. Cuspidariids, like parilimyids, feed on swimming prey, the long inhalant siphon being everted upwards. This also suggests a phylogenetic link, the cuspidariids being the more specialized members of this group. The Palaeozoic and Mesozoic extinctions of large numbers of anomalodesmatans have left few living descendants and these show widely divergent character traits, making the construction of lineages difficult. However, modern descendants of these early abyssal colonists indistinctly linked, seem to feed on two groups of organisms; bottom-dwelling crustaceans and annelids (Verticordiidae and Poromyidae) and swimming crustaceans (Parilimyidae and Cuspidariidae).

Redescription of the genus Shikamaia, and clarification of the hinge characters of the family Alatoconchidae (Bivalvia)

A new full description of the bivalve Shikamaia akasakaensis Ozaki (genotype species of Shikamaia) is presented, providing the first documentation of its hinge and ligament, and resolving many uncertainties about Shikamaia, the first described genus of the Permian bivalve family Alatoconchidae. The genus Shikamaia has a unique ligament, modified from typical duplivincular ligaments in occupying only half of the cardinal area, and having ligament sheets that extend themselves towards the beak with continued growth. This ligament is strikingly different from the ligaments of other alatoconchid genera. All alatoconchids are believed to have a common ancestry, but the magnitude of difference in their hinges warrants dividing the family into two subfamilies. The subfamily Saikraconchinae is erected new.

Biases in the durations and diversities of fossil taxa

The theoretical framework developed here delineates the biological and paleontological circumstances under which the observed durations and diversities of fossil taxa will be significantly affected by three time-dependent sampling biases. The pull of the Recent and the loss of fossiliferous sediments shorten the observed durations of ancient taxa, as compared to the observed durations of Recent taxa. By contrast, the duration truncation mechanism lengthens the observed durations of ancient, as compared to more recent, taxa. Both the pull of the Recent and loss of fossiliferous sediments decrease the observed diversity of ancient, as compared to contemporary, communities.This theoretical framework is built on four parameters: the extinction and origination rates q and p; the fossilization rate, v; and the fossil loss rate, h. I derive formulas for the observed durations and diversities of fossil taxa in terms of these parameters and develop a method of estimating these parameters. The estimation procedure is applied to the bivalve families, and I provide statistical evidence for the conclusion that q – p < 0 for bivalve families, and hence that bivalve diversity has been increasing through time. The theory predicts that a certain fraction of an extinct fauna will be represented by only one fossil, and hence will have an observed duration of zero. As the record becomes poorer, this fraction increases. For bivalves I assume that families known from only one stage have an observed duration of zero, and exploit this assumption to estimate h and v/p.To evaluate the errors made in applying the model to the bivalves, I estimate several parameters in two different ways and find the estimates to be consistent. Additionally, I argue that the errors caused by the simplifying assumptions of the model are less than the sampling errors inherent in estimating p, q, h, and v.

THE EFFECTS OF CALCIUM ON SEROTONIN-STIMULATED ADENYLATE CYCLASE IN FRESHWATER MUSSELS

When serotonin (5-HT) is added to a pondwater bath (final concentration, 10-4 M/l) containing freshwater mussels, sodium influx is rapidly stimulated, as are behavioral responses. Serotonin also stimulates adenylate cyclase (AC) in gill homogenate pellets from two different freshwater bivalve families, suggesting that a serotonin-cAMP system is associated with control of Na transport and that this system may be common in many ion regulating mussel species. Adenylate cyclase activity was detected in several tissues of Ligumia subrostrata; the highest activity being observed in the foot. Endogenous calcium depressed the AC activity measured under basal, 5-HT, and dopamine stimulated conditions; the reduced enzyme activity was most pronounced in the monoamine stimulated preparations. AC activity of the crude homogenate pellet was significantly lower than a purified pellet formed by an additional 100 x g centrifugation prior to a 3000 x g centrifugation. Exogenous calcium (2.5 mM/l) inhibited monoamine stimulated AC activity about 50%. Calcium concretions exist in gill tissue and may influence the observed AC activity by increasing the protein measure or increasing the calcium concentration. Prostaglandin E2 had no effect on basal or 5-HT stimulated AC activities in the purified pellet. Although phosphodiesterase and non-specific phosphatase activities were high in the supernatant, their activities in the homogenate pellet were low and had little effect on the AC activity measurements.

Rarefaction and Taxonomic Diversity

Rarefaction is a technique that corrects for unbalanced sample sizes, which are often a major problem in comparisons of diversity. The rarefaction curve is the expected number of higher taxonomic groups, such as families or genera, represented in a random selection of lower taxonomic units, such as species or individuals. The shapes of these curves are analyzed by finding the best possible uniform upper and lower bounds for a fixed number of units and groups. The position of a rarefaction curve between these limits provides a natural measure of evenness of diversity. Asymptotic formulae are also given. The results are applied to the distribution of species within families of recent echinoids and bivalves.

The larval and post-larval hinge of some families of bivalve molluscs

Bivalve larvae constitute an important part of the plankton and there is a pressing need to be able to identify the various species.The study of the development of the larval and post-larval hinge by scanning electron microscopy of 18 bivalve species shows the importance of this structure, which represents the principal character in identification of the young larval stages. This paper presents the principal distinguishing characters of the hinge (denticles, teeth and ligament) in eight families of bivalves.

Spat Settlement of the Scallops Chlamys Opercularis (L.) and Pecten Maximus (L.) On Artificial Collectors

Scallops of the bivalve family Pectinidae are very valuable shellfish and the subject of various important commercial fisheries around the world. Most of these fisheries are at present dependent upon natural populations, which can fluctuate widely in abundance from year to year due to irregular recruitment and overfishing. In recent years there has been considerable interest in the possibilities of cultivating various scallop species and some success has been obtained in rearing larvae of Pecten maximus (L.) in the laboratory (Comely, 1972; Gruffydd & Beaumont, 1972). However, by far the most successful cultivation system developed for pectinids has been carried out for several years in Japan for Patinopecten yessoensis (Jay). Naturally produced spat settling on Collectors made from artificial materials are grown on to market size in cages in the sea or used to restock natural beds (Ito, Kanno & Takashashi, 1975; Querellou, 1975; Motoda, 1977).

Uptake of sodium and chloride by freshwater mussels

Ion transport rates were measured in six species representing the four families of freshwater bivalves in North America. Sodium and chloride transport systems function independently in all of the species. The unionid steady-state influx of Na and Cl was about 1 μ equiv/g dry tissue per hour. Margaritifera hembeli Na influx was about 5 μ equiv/g dry tissue per hour and they were in a positive Na balance. Chloride influx by M. hembeli was similar to the unionids. The Sphaeriacea transport Na and Cl at significantly higher rates than Unionacea. Corbicula manilensis Na and Cl influx was about 9 μ equiv/g dry tissue per hour. Sphaerium transversum Cl influx was similar to C. manilensis; however, Na influx was twice as high. The higher transport rates of the Sphaeriacea are similar to brackish-water animals. Sodium, Ca, and Cl are major ions in the blood of all species. Bicarbonate is a major anion (19–12 mM/L) in all species except C. manilensis (4 mM/L).

Aspects of the adaptive morphology and evolution of the Trigoniidae

During the Jurassic and Early Cretaceous, the Trigoniidae were the dominant family of shallow-burrowing bivalves of warm, shallow seas. Neotrigonia is the only genus that survives today. Judging from the biology of Neotrigonia and the functional morphology and occurrence of extinct genera, the Trigoniidae represent an advanced family of burrowing Bivalvia. The family has been characterized by efficient locomotion, owing in large part to the presence of an unusually muscular foot, resembling that of the living Cardiidae. Other unusual features of the Trigoniidae relate to the presence of the foot. Complex hinge teeth with secondary dentition evolved to maintain valve alignment at the wide angles of gape required for extrusion of the foot. Myophorous buttresses evolved to support the large anterior hinge teeth. These anterior features seem to have obstructed the evolution of a prosogyrous shape of the kind that facilitates burrowing within many other bivalve taxa. Alternatively, there evolved in the Trigoniidae various kinds of external shell ornamentation that aided in burrowing. Thus, the many unusual morphological features of the Trigoniidae have been strongly coadaptive. The Mesozoic Trigoniidae seem to have been more advanced animals than any shallow-burrowing, suspension-feeding bivalves of the Palaeozoic and also than certain successful living groups with similar modes of life. Though slightly less advanced than the Cardiidae, they can be regarded as the cockles of the Mesozoic. Had the group not suddenly been decimated by environmental deterioration at the end of the Mesozoic, it would undoubtedly flourish today. Neotrigonia has, in fact, speciated at a high rate in comparison with other living genera of bivalves. A relatively recent origin and lack of primitive features disqualify Neotrigonia from status as a living fossil genus. It is the sole survivor of its family, but an advanced and modern animal nonetheless.

A new species of trigoniid bivalve from the Boreal Bathonian (Jurassic) of central East Greenland

A brief description is given of Vaugonia athena sp. nov. from the Borea! Bathonian Ishmae Zone of Olympen, Jameson Land, one of the rare known representatives of the bivalve family Trigoniidae in the Boreal Realm of the Jurassic. Its affinities lie with Middle Jurassic species from western North America and with an early Bajocian species from northwestern Europe, but it differs from contemporaneous forms in the Bathonian of Britain.

The adenosine triphosphate content of some marine bivalve molluscs

The total ATP-content of representatives of 23 bivalve families was found to vary from 1.26–0.26 % of the dry tissue weight, with the dry tissue containing about 40 % carbon. Representatives from certain families consistently had more than average and others less than average ATP values, and there were greater differences between species from different families than between closely related species. Variations in the oxygen uptake of whole animals accounted for little of the observed variation in ATP-content. The ATP-content of individual tissues from the same individual showed wide variation, as did that of the same tissue from different species. The highest values of ATP were found in muscle tissues. High maintained levels of ATP were associated with the ability of the species to use energy rapidly for short periods, for example, in escape responses.

ADAPTATIONS IN GRAMMYSIA OBLIQUA

The Grammysiidae are an important but little understood family of Paleozoic bivalves. Specimens of Grammysia obliqua (McCoy) from the Stonehouse Formation (Uppermost Silurian), Nova Scotia, permit interpretation of their functional morphology and autecology. Grammysia obliqua was an immobile, semi-infaunal, filter-feeding bivalve. It lived fixed by a byssus, with the shell inclined about 40° to the sediment-water interface. Though incapable of opening the shell, the animal maintained contact with the environment through byssal and dorsal-posterior gapes. This latter gape was in a peculiar position for a bivalve and required some anatomical adaptation, but it was functionally efficient for the animal's life attitude.

Genera of the Bivalve Family Mesodesmatidae, with Comments on some Australasian Species

Abstract The status of major genus-group names in the Mesodesmatidae is reviewed. Genera recognised in the Subfamily Mesodesmatidae are Donacilla de Blainville. 1819, Mediterranean Mactropsis Conrad. 1854. Tertiary of North America; Atactodea Dall, 1895, Indo-West Pacific; doubtfully Ceroniola Wilckens, 1904, Upper Cretaceous of South America; and Paphies Lesson [1831], with subgenera Paphies s.str., New Zealand; Mesodesma Deshayes [1832] (= Taria Gray, 1853), eastern and western South America, and New Zealand Amesodesma Iredale, 1930, south-eastern Australia: and Ceronia Gray, 1853, eastern North America. Other generic names in the family are briefly reviewed, and the preoccupied Nesis “Monterosato” Locard, 1899, is renamed Monterosatus. Paphies (Amesodesma) perfuga (Iredale, 1930), type species of Amesodesma, is synonymlsed with Paphies (Amesodesma) angusta (Reeve, 1854). It Is suggested that Mesodesma quoyi Deshayes, [1832] is an earlier name for Paphies (Mesodesma) forsteriana (Finlay, 1927), which in turn is inseparable from P. (Mesodesma) pilocenica (Oliver, 1923). Myadesma Clark, 1922, seems to belong in the Mactracea, but is placed in the family Myadesmatidae Clark, 1922, rather than in the Mesodesmatidae.

Cretaceous lamellibranchs of family Trigonioididae and their classification

The unusual freshwater bivalve family Trigonioididae (Cox) is poorly known and has only recently been sufficiently studied to construct a taxonomy and phylogenetic relationships. Previous work is reviewed and evaluated. Recent accumulation of abundant trigonioids from the Far East, Mongolia, China, West Kazakhstan, Fergana depression, western spurs of the Hissar Range, and the Kyzyl Kum makes possible taxonomic reevaluation of the family, construction of a more complete phylogeny, and recognition of evolutionary trends. Previous ideas that the Trigonioididae had a geographic range restricted to border zones of eastern Asian seas are discarded, as in the single-character taxonomy based predominantly on shell ornamentation. A taxonomic system is proposed employing shell size, shape, convexity, exterior ornament patterns and hinge characters. Evolutionary trends and diversification in one character do not necessarily coincide with changes in other taxonomically important characters. Five genera are described...

The Fresh-Water Pearls of America

THE production of pearls by numerous species belonging to the fresh-water bivalve family Unionidae has been a matter of common knowledge from time immemorial. Such pearl-bearing mussels occur in the Tay, Isla, and several others of the rivers of the British islands, as well as in many of those of the continent, Mesopotamia, China, and North and South America. As a rule, however, such fresh-water pearls, in Europe at least, are inferior in lustre, and consequently in value, to those obtained from the pearl-oyster; and in those British rivers which produce the pearl-bearing species of Unio, it is stated that on the average one pearl is found in every hundred shells, and that only one pearl out of a hundred is fairly clear. During the eighteenth century, however, a considerable number of Irish pearls, ranging in value between 4l. and 10l., were obtained, while one specimen, when mounted, realised 80l. In Scotland, pearls worth from 3l. to 4l. each are not unfrequently found, and it is stated that as much as 100l. has been paid for an unusually fine example. According to Dr. P. L. Simmonds, between the years 1761 and 1764 ten thousand pounds' worth of Scotch pearls were sent to London, while in the corresponding decade of the present century the amount was considerably more than double that value. During the dry season of 1862, when the lowness of the streams-rendered the fishing unusually favourable, more pearls were collected than in any previous year; and the average price consequently fell to fifty shillings, or less. Twenty years ago, when from 5l. to 20l. was obtained for fine specimens, the general price was, however, much higher; and one Scotch pearl, for which forty guineas was given, is the property of the Queen.