Gastropod Family Research Articles

Higher order assemblies of molluscan hemocyanins

1. The hemocyanins of the Fissurellidae, Naticidae and Melongenidae families of marine gastropods as well as some other molluscs including some members of the Opistobranchia and Bivalvia groups have hemocyanins which exist in solution as tri-decameric and mixed, multi-decameric aggregates characterized by sedimentation coefficients close to 100 S, 130 S, 150 S, 170 S and 200 S to 230 S. 2. The particle masses of the molluscan hemocyanins appear to be integral multiples close to 4.4 x 10(6) daltons. Thus, particle mass values of 4.47 x 10(6), 8.67 x 10(6) and 13.40 x 10(6) daltons were obtained for representative decameric, di-decameric, and tri-decameric components of Stenoplax conspicua, Fasciolaria tulipa and Euspira (Lunatia) heros hemocyanins. For Busycon contrarium, a gastropod with a mixed multidecameric hemocyanin, scanning transmission electron microscopic (STEM) measurements gave particle masses ranging from 8.89 x 10(6) and 13.20 x 10(6) for the di- and tri-decameric components to 38.87 x 10(6) and 43.40 x 10(6) daltons for highest nano- and deca-decameric aggregates. 3. The electron microscopic images of both uranyl acetate-stained and unstained specimens of hemocyanin aggregates indicate a non-random mode of assembly of the multi-decameric particles. This is most apparent from the electron micrographs of the moon snail hemocyanins. The tri-decameric and tetra-decameric particles seem to be assembled from a single di-decameric unit of the Mellema and Klug arrangement, with the collar ends facing outward, to which decameric units have been added from one or both ends, in a unidirectional tail-to-head to tail-to-collar manner. Consequently, all the aggregates including the higher, Melongenidae polymers have the appearance of closed cylinders terminating with the collar ends. 4. The radial distribution of the end-on views of the hemocyanin of the moon-snail Calinatioina oldroydii, show that the radial mass drops to zero at the center of the cylindrical particles consisting of one, two, or three decamers. This suggests that no caps are present at the ends of the hemocyanin particles which would inhibit or terminate their linear assembly. 5. The light-scattering behavior of B. contrarium and Marisa cornarietis hemocyanins examined as a function of increasing reagent concentration using the hydrophobic urea and Hofmeister salt series of reagents, show distinct aggregation and increase in molecular weights at low concentrations of reagent. Together with the stabilizing influence of Mg2+ and Ca2+ ions, this suggests polar and ionic stabilization of the inter-decameric contacts between the central di-decamers and the added decameric units of the higher aggregates of molluscan hemocyanins.(ABSTRACT TRUNCATED AT 400 WORDS)

Subunit structure of the hemocyanins of some of the muricidae and fasciolariidae families: Chicoreus florifer dilectus (A. Adams), Muricanthus fulvescens (Sowerby), Urosalpinx cinerea (Say), Fascilaria lilium hunteria (Perry), and Pleuroploca gigantea (Kiener)

1. 1. The hemocyanins of the Muricidae and Fasciolariidae families of marine gastropods: Chicoreus florifer dilectus, Muricanthus fulvescens, Urosalpinx cinerea, Fasciolaria lilium hunteria, and Pleuroploca gigantea were investigated by sedimentation velocity, scanning transmission electron microscopy, light-scattering, and other physical techniques. 2. 2. The hemocyanins of these species are characterized by sedimentation coefficients close to 100 S and molecular weights of 8.2 × 10 6–9.0 × 10 6. 3. 3. The hemocyanins have di-decameric structures, with tail-to-tail arrangement of the decameric halves of the cylindrical particles. Only the hemocyanin of U. cinerea was found to contain about 30% higher, tri-, and tetra-decameric particles, with one or two decameric units added in a tail-to-head manner to a central di-decameric particle of the Mellema and Klug tail-to-tail arrangement. 4. 4. The influence of pH, and the urea and Hofmeister salt series of reagents on the subunit structure and denaturation of P. gigantea hemocyanin were also investigated.

New species, anatomy, and systematic position of the hydrothermal vent and hydrocarbon seep gastropod family Provannidae fam.n. (Caenogastropoda)

The anatomy of the hydrothermal vent gastropod Provanna is described. It is shown to be a primitive neotaenioglossan with mainly plesiomorphic features in all systems, including open pallial gonoducts, epiathroid nervous system with accessory pedal ganglia and a circulatory system where a considerable portion of the venous blood from the coelomic spaces enters the pallial skirt. Apomorphic features include the possession of an anterior notch, or short canal in the shell (and mantle edge), an annulated sensory pallial tentacle, paraspermatozoa modificd as nurse cells. multiple seminal receptacles, a posterior bursa copulatrix, and a renal oviduct with three distinct regions. the middle one expanded. Comparisons are madc with Abyssochrysos, a genus assumed to be a relict member of the Loxonematoidea, which appears to be the closest known relative. A new family. Provannidae fam.n., is created and tentatively included in the Loxonematoidea. The following new specics are described: Provanna segonzaci sp.n. (from hydrothermal vents at the Fiji Back Arc), P. laevis sp.n. (from hydrothermal seeps in the Gulf of California), P. sculpta sp.n. and P. admetoides sp.n. (from hydrocarbon seeps in the Gulf of Mexico). New records are added for previously described species of Provanna.

Species of Naticidae (Mollusca: Gastropoda) described by Linnaeus in the Systema Naturae (1758)

In the Systema Naturae (1758) Linnaeus described seven species now placed in the gastropod family Naticidae. This study documents their identity based on critical re-examination of original descriptions and original specimens in the Linnean Society of London and the Zoologiska Museet of Uppsala Universitet. The six valid species are redescribed; the other is a nomen dubium. Four of the species are type species of currently accepted naticid genera.

Subunit structure and higher order assembly of the hemocyanins of five members of the naticidae family of marine gastropods: Calinaticina oldroydii (DALL), Euspira heros (SAY), Neverita Duplicata (SAY), Polinices draconis (DALL), and Polinices lewisii (GOULD)

1. 1. The hemocyanins of the Naticidae family, E. heros, N. duplicata, P. draconis, P lewisii and C. oldroydii were investigated by sedimentation velocity and scanning transmission electron microscopy. 2. 2. At pH 8.0, 0.05 M Mg 2+ E. heros hemocyanin is found to be predominantly in the tri-decameric state with a sedimentation coefficient ( s 20 o , w ) of 131.3 (±0.6) S. While the hemocyanin of N. duplicata is also mainly in the 130 S form, the hemocyanin of C. oldroydii is largely in the di-decameric form with a sedimentation coefficient close to 100 S. Other Naticidae hemocyanins, those of P. lewisii and P. draconis, have mixtures of the 100 S and 130 S di- tri-decamers, and minor amounts of 150 S and faster sedimenting components. 3. 3. The average particle masses based on STEM measurements are 8.85 × 10 6. 13.3 × 10 6, and 17.1 × 10 6 da for the di-, tri-, and tetra-decameric assemblies hemocyanin. 4. 4. The subunit mol. wts of C. oldroydii hemocyanin and the published values for E. heros hemocyanin at alkaline pHs and in the presence of 8.0 M urea range from 4.2 × 10 5 to 4.8 × 10 5, suggesting the same decameric organization of the sub-assemblies of the Naticidae hemocyanins as for other molluscan hemocyanins. 5. 5. The appearance of the larger hemocyanin particles in the electron micrograph support the hypothesis for their assembly that was based on similar studies of the hemocyanins of the Melongenidae family. According to this scheme the formation of higher aggregates is accomplished by the tail-to-head addition of each decameric unit to a central di-decamer which itself has the tail-to-tail Mellema and Klug arrangement of decamers. In this model all the higher aggregates terminate from either end with the same “collar” ends.

A new genus of aporrhaid gastropod from southern California

A paleoecological study of the Point Loma Formation (Upper Cretaceous, southern California) resulted in the discovery of a new genus assigned to the gastropod family Aporrhaidae. The individuals recovered provide the basis for the designation ofTenepositan. gen. based uponT. laevan. sp.Tenepositais characterized by two delicate labral digitations, a short opposing digitation, and elongate anterior and posterior canals.Teneposita laevais one of the smallest aporrhaids yet described.

The comparative morphology, phylogeny and evolution of the gastropod family littorinidae

An account is given of the comparative morphology of the family Littorinidae, based on examination of 122 species, grouped into 32 subgenera. The shell, operculum and principal organ systems are described, and their phylogenetic significance assessed. A total of 53 characters, coded as 131 character states, were chosen for inclusion in a cladistic analysis of the phylogenetic relationships of the subgenera. This was performed by the program paup, using the principle of maximum parsimony. The outgroup for the analysis comprised representatives of the Pomatiasidae and Skeneopsidae. A consensus tree was obtained from cladograms with consistency indices of 0.408 (autapomorphies excluded).

The diet of coral-reef Mitridae (Gastropoda) from Guam; with a review of other species of the family

The diets of 16 species of the gastropod family Mitridae from coral-reef habitats around the Pacific island of Guam were investigated by gut content analysis. All species examined were specialist feeders upon sipunculans, with considerable dietary overlap between coexisting species. A review of the diets of mitrids from other places, shows that a sipunculan diet is now known for a total of 26 species. The family is the most trophically specialized of the more speciose gastropod families.

Subunit structure and higher order assembly of the hemocyanins of the melongenidae family: (Melongena corona (Gmelin), Busycon canaliculatum) (Linné), B. carica (Gmelin), B. contrarium (Conrad), and B. spiratum (Lamarck)

1. The hemocyanins of the Melongenidae family of marine gastropods: Melongena corona, Busycon canaliculatum, B. carica, B. contrarium, and B. spiratum exist in solution as multi-decameric aggregates characterized by sedimentation coefficients of approximately 105 S, 130 S, 150 S, 170 S, and higher values, corresponding to di-, tri-, tetra-, penta-, and larger multi-decameric particles. 2. The hemocyanins of B. contrarium and B. carica seem to form the largest decameric aggregates with the tri- to penta-decamers respresenting the major constitutents. Scanning transmission electron microscopy (STEM), both of unstained, freeze-dried and negatively-stained specimens, shows the presence of discrete aggregates consisting of up to ten decameric units. 3. The particle masses as determined by STEM mass measurements for individual molecules gave integral multiples of from 4.2 x 10(6) to 4.4 x 10(6) daltons ranging from about 8.2 x 10(6) daltons for the typical di-decamer of B. canaliculatum hemocyanin to as high as about 39 x 10(6) and 43 x 10(6) for the nano-and deca-decamers of B. contrarium hemocyanin. 4. The appearance of the higher multi-decamers in both negatively-stained and freeze-dried specimens suggest that they are formed by the addition of decameric units to a single di-decameric unit "tail-wise" in both directions. The higher aggregates formed seem to terminate with a closed head or collar at both ends of the assembly.

How good was the fossil record? Clues from the Californian Pleistocene

The living members of 113 families of bivalves and gastropods of the Californian Province include 698 species living at shelf depths, of which 538 or 77% are known as Pleistocene fossils from the same region; another 113 fossil species are extralimital, and 98 are extinct. Living species not found as fossils are chiefly rare today, and/or minute, fragile, and/or from deeper shelf habitats. Sampling of the Pleistocene record has been biased towards shallow-water assemblages. Fragile and minute forms are probably underrepresented in the record. Rare forms, however, are still appearing as new studies are conducted, and many rare species are yet to be discovered. At least 85% of durably skeletonized living species may have been captured in the record. It is probable that most durably skeletonized invertebrate species were represented in lithostratigraphic units throughout the Phanerozoic, but that this record is lost owing to erosion, burial, and destruction of skeletons in situ. The bulk of the marine invertebrate fossil record does not represent a series of unusual skeletal accumulations, but rather the preserved remnants of an excellent original record formed through ordinary though episodic processes.

Genetic diversity and resistance to marine pollution

We tested in the laboratory three pairs of species belonging to three genera and families of marine gastropods, Monodonta turbinata, M. turbiformis (Trochidae), Littorina punctata, L. neritoides (Littorinidae), Cerithium scabridum, C. rupestre (Cerithiidae), for resistance to diverse inorganic (heavy metals and NaC1) and organic (detergents and crude oil) pollutants. Each pair consisted of one narrow-niche species with low genetic diversity and one broad-niche species with higher genetic diversity. Evidence is presented that in all three cases the species with a higher level of genetic diversity was more resistant to all pollutants than its counterpart. These results suggest that fitness is positively correlated with heterozygosity and support the niche-width-variation hypothesis in regard to pollutants. The results also have practical implications for the identification of optimum marine species as genetic monitors of pollution.

Glacidorbidae (Glacidorbacea: Basommatophora), a new family and superfamily of operculate freshwater gastropods

Some aspects of the anatomy of Glacidorbis hedleyi Iredale are described and its systematic position is reviewed. Glacidorbis is a genus of operculate gastropods found in Australia and South America, the species of which possess a monoseriate or triseriate radula and brood their embryos in the pallial cavity. Glacidorbis hedleyi is a protandrous hermaphrodite with, sometimes, 50% or more of large individuals remaining as males. The reproductive system is diaulic, with the penis being lost in mature females. It feeds on the tissue of freshly killed or wounded animals and has a very simple alimentary canal. A new family and superfamily is created for Glacidorbis within the Basommatophora. A new subgenus, Gondwanorbis, is introduced for Glacidorbis magallanicus Meier-Brook & Smith from Chile, S America.

Relationships of gymnomorph gastropods (Mollusca: gastropoda)

The gastropod families Onchidiidae, Vaginulidae, Rathouisiidae and Rhodopidae have been classified in a subclass Gymnomorpha, in which the genus Smeagol has been more recently included, on the basis of characters related with limacization which should not be used for classification at suprafamilial levels. When only characters not related with limacization are taken into account, the onchidiids are very similar to the ellobiids; Smeagol may be considered an otinid slug; vaginulids and rathouisiids form a monophyletic group of pulmonates, the Rathouisioidea. It is proposed to reject the Rhodopidae from the Pulmonata, and to include the onchidiids and the Rathouisioidea in the order Archeopulmonata, together with the ellobiids, the otinids and the Amphiboloidea.

CHROMOSOMAL EVIDENCE FOR PARALLEL EVOLUTION OF SHELL SCULPTURE PATTERN IN GONIOBASIS.

The complex patterns of geographic variation exhibited by many groups of freshwater molluscs present some extremely difficult evolutionary and taxonomic problems. A common pattern among members of the gastropod family Pleuroceridae (Mesogastropoda) is the downstream replacement of a relatively smooth-shelled form or by a more sculptured form or (Adams, 1915; Goodrich, 1934, 1935; Rosewater, 1960). This pattern is displayed by the pleurocerid Goniobasis fioridensis (Reeve) and Goniobasis dickinsoni Clench and Turner in the Chipola River drainage and Holmes Creek: two adjacent streams that occur in different river basins in the Florida panhandle. The Chipola River is in the Apalachicola River Basin, and Holmes Creek is in the Choctawhatchee River Basin. Goniobasis dickinsoni occurs in the upper reaches of the Chipola River and some upper tributaries of the Choctawhatchee River Basin, including Holmes Creek. Goniobasis fioridensis occurs in lower reaches of Holmes Creek and the Chipola River as well as in most Florida river systems lying to the east (Clench and Turner, 1956). The shells of G. dickinsoni are smooth or have faint to moderate ribs on the whorls. Goniobasis fioridensis shells are heavily sculptured with ribs intersecting spiral cords to form nodules (Fig. 1). These species intergrade where their ranges overlap within the Chipola River drainage. Adult shells with sculpture patterns varying between those of G. dickinsoni and G. floridensis are found in this intergrade zone; which, following the terminology of Woodruff (1973), may be called a zone of widespread sympatric hybridization. These do not intergrade in shell sculpture where their ranges overlap in Holmes Creek. An electrophoretic analysis of 18 allozyme loci (Chambers, 1980) indicated little divergence between these in the Choctawhatchee and Apalachicola river basins. Genetic distance values, as measured by the genetic distance index (D) of Nei (1972), between samples of these different ranged from 0.008 to 0.068. Genetic distances between samples of G. dickinsoni from the two different basins were 0.057 and 0.072. Genetic distances between G. floridensis samples from these different basins were 0.046 and 0.060. These values are comparable to the average values calculated for conspecific populations of other animal (Ayala, 1975). Since nearly all common alleles were shared by populations of the two species, there is little or no allozyme evidence for reproductive isolation between them. The present study was undertaken to determine if chromosomal differences might explain the different relationships of the two forms within the two different river basins. The results of the karyotypic analysis indicate that, although there is no evidence for chromosomal involvement in divergence between forms, there is chromosomal divergence between populations from Holmes Creek and the Chipola River drainage that suggests the parallel evolution of similar shell sculpture patterns.

The Origin and Evolution of the Gastropod Family Pomatiopsidae, with Emphasis on the Mekong River Triculinae.

The Origin and Evolution of the Gastropod Family Pomatiopsidae, with Emphasis on the Mekong River Triculinae.

Sand collars from a Recent beach

Sand collar structures that occur on Recent beaches near river mouths, between the high and low water lines, are made up of line silt and sand and enclose the egg masses of certain families of gastropods. The eggs are minute in size, about 10 μm in the longer axis and 5 μm in the broader part, with wavy and knobby features on the surface as identified by the study of inner surfaces of the structure with the scanning electron microscope. The mineralogy of the structures is similar to that of the surrounding sediments. They can be useful in drawing an analogy between the present environment and the past if detected in older sediments.

Morphological patterns in high-intertidal gastropods: Adaptive strategies and their limitations

An analysis of shell form in several families of high-intertidal herbivorous gastropods has revealed the existence of morphological gradients. Among tropical littorinids, relative spire height and degree of development of external shell sculpture generally increase interspecifically, and often intraspecifically, from low to high shore levels. This gradient is also evident from temperate to tropical latitudes, and may be modified or overridden by exposure to wave action and other factors. Among acmaeid, patellid, and siphonariid limpets, there is a well-marked interspecific increase in relative shell height with increasing shore level, but latitudinal trends in morphology cannot at present be distinguished. Evidence from both tropical and temperate coasts indicates that limpets found in shaded places tend to have smoother shells than those often exposed to direct sunlight. In the Neritidae, relative shell globosity tends to increase interspecifically from low to high shore levels; most high-shore species have strong shell sculpture, with the base of the shell only slightly excavated. A decrease in the number of neritid species towards higher latitudes is accompanied by selective deletion of globose, strongly sculptured types living at high shore levels. Neritids and some limpets can employ evaporative cooling as a mechanism for temperature regulation. The morphological gradients in these groups reflect a relative increase in the volume of the extravisceral cavity (water reservoir) and a decrease in the area in contact with the substratum, as well as a relative decrease in the rate of water loss, in an upshore direction. Neritids are better adapted than limpets to high temperature and desiccation stresses because of their ability to regulate rate of evaporation and contact between soft parts and substratum. These differences are reflected in the complementary patterns of latitudinal diversity in the two groups. In Littorinidae, which attach to the substratum by a mucus film, the morphological gradients reflect a minimization of water loss and substratum contaet, and a maximization of reflective relative to absorptive surface area.

Anatomy and Systematics of the Neotropical Strophocheiloidea (Gastropoda, Pulmonata) with the description of a new family

The family Strophocheilidae (sensu Bequaert, 1948) is here divided into two - Strophocheilidae s.s. and Megalobulimidae, fam. n., on the basis of anatomical characters. New diagnoses are given for the genera of Strophocheilidae and a new systematic arrangement of the Neotropical Strophocheiloidea proposed. Representatives of 16 families of terrestrial, fresh-water and marine pidmonate gastropods were studied, besides some species of Prosobranchia and Opisthobranchia. Representatives of families of Pulmonata were selected to represent diverse evolutionary trends.

Feeding of the Cymatiid Gastropod,Argobuccinum argus, in Relation to the Structure of the Proboscis and Secretions of the Proboscis Gland

Several gastropod families belonging to the superfamily Tonnacea are known to bore into the calcareous shells of echinoids and bivalves, but little work has been done on the family Cymatiidae. New observations show that the cymatiid, Argobuccinum argus , which feeds on the tubicolous polychaete, Gunnarea capensis , possesses large proboscis glands which secrete 0.4 to 0.5N H2SO4; further, the secretion dissolves greater amounts of pure CaCO3 than does O.47N H2SO4, alone. A toxin is also present, which abolishes responses to light and touch in several invertebrates. The proboscis is atypically pleurembolic, having a permanent proboscis sheath. Retraction is due to the muscles ot the proboscis wall, and the contracted proboscis is not inverted. Unlike other mesogastropods, the Tonnacea have three pairs ofglands associated with the foregut: proboscis glands, true salivary glands, and a small, partly paired gland of unknown function immediately posterior to the buccal mass. It is concluded that because of an abundance of readily available food in the form of Gunnarea, A. argus does not drillinto animals protected by a calcareous shell. The presence of a CaCO3 dissolving mechanism indicates that the Cymatiidae ingeneral may be able to employ this method of feeding.

Acrylylcholine: a new naturally occurring pharmacologically active choline ester from Buccinum undatum

Extracts of the hypobranchial gland of the prosobranch marine gastropod Buccinum Undatum (common whelk) has been found to have a very high acetylcholine-like activity (equivalent to about 0.3 μmoles acetylcholine/g tissue) when assayed on the frog rectus abdominis muscle. So far, high hypobranchial acetylcholine equivalences have been known to occur only in the dye-secreting family of prosobranch gastropods, Muricidae, to which Buccinum does not belong. The active principle has been identified as acrylylcholine and is thus related to the two esters which have been isolated previously from Muricidae, urocanylcholine (4(5)-imidazolylacrylylcholine) and β, β-dimethylacrylylcholine.