The reproductive ability of 1254 breeding individuals of Helix pomatia originating from a local wild population were studied. Reproduction was carried out in a greenhouse at a stocking density of 51.2 breeding snails per m². The reproductive season was 83 days long. From 30 May to 21 August 2003 almost all the snails laid eggs at least one time, but 25.1% of the snails laid eggs twice, and 5.2% laid eggs three times. The mean number of eggs per clutch for all the breeding snails was 41.7. Because of the multiple laying of eggs, the number of eggs laid in the 2003 season averaged 61.5 per breeding snail, and the eggs' total biomass constituted 38.5% of the biomass of all breeding individuals. A significant (P < 0.05) increase in egg laying was found from 30 May to 21 July. This period was followed by a rapid decline in reproductive intensity, until egg laying ceased on 21 August. Breeding snails laid 77100 eggs, out of which 40000 eggs hatched. From the hatched eggs 27000 two-to-three-week-old hatchlings were obtained. Of the obtained hatchlings 15000 were released into a greenhouse; 32.0% of these individuals survived winter hibernation in a pen. In May of the next year, the 4800 hatchlings were released into a field pen, at a density of 260 specimens per m². They reached a mean body mass of 19.1 g and mean shell diameter of 30.1 mm in July. The rapid rate of growth observed under farm conditions allows us to propose a two-year farming cycle for this species, from hatching to the stage of sexual maturity.

Individuals of Amphissa columbiana from the intertidal zone of San Juan Island, Washington, U.S.A., typically have either shells with very thin, delicate apertural lips, or shells with thick, robust lips. In laboratory observations, thin-lipped snails grew rapidly but were not sexually mature, while thick-lipped snails grew very slowly or not at all and were sexually mature. These observations are consistent with the hypothesis that A. columbiana displays determinate growth, as has been inferred for many columbellids on the basis of intraspecific variation in shell form. Sizes of mature snails were very variable, with the largest individuals weighing 4.5 times more than the smallest (wet weight, excluding shell). I tested the hypothesis that maturation and associated shell thickening are phenotypically plastic responses to the presence of predators. Exposure to effluent from the predatory crab Cancer productus in the laboratory had no effect on shell form or relative shell weight (an index of shell thickness), suggesting that this is not the case.

A survey of the micro-land snails in the mountain rainforest or “Yungas” of Tucumán Province, Northwestern Argentina (26°20′–27°30′S) was carried out. A total of 75 samples were processed from 25 stations of 10 × 10 m each. We identified the snails collected to species level and built a species per station data matrix to analyze patterns of diversity. Non-parametric estimators (ICE and Chao2) using EstimateS 5.0.1 were used to estimate the true diversity of the area, the degree of undersampling, and spatial aggregation in the data. Other diversity measurements such as Shannon and Whittaker indices were also calculated. Our study estimated the micro-mollusc species richness of the Yungas of Tucumán to be 21 species distributed among 9 families, with a notably high number of specimens collected (7741). The most speciose family was Charopidae with a total of seven species identified. However, the most abundant families were Diplommatinidae and Systrophiidae. Adelopoma tucma and Wayampia trochilioneides were the most abundant species, the least frequently found species was Lilloiconcha tucumana. The non-parametric estimators showed that our survey was complete and that patchiness did not affect diversity estimations. San Javier and Escaba stations had the highest species richness, the most diverse station was Escaba. Most previous studies in other places in the world show high species richness and low density of specimens. In Tucumán, on the contrary, the absolute abundance of specimens was high with a low species richness.

The genus Belloliva (Gastropoda: Olividae) consists of small (<15 mm) operculate species and was hitherto thought to be essentially confined to coastal waters of southern and eastern Australia. We report a small radiation from deep water (100–1000 m) in the Coral Sea and New Caledonia, consisting essentially of undescribed species. The new genus Calyptoliva, which differs from Belloliva by the absence of a mantle filament and the presence of a mantle lobe, is also represented in the same area by new species. Based on correlation with shell characters, we suggest that the olivid mantle lobe is responsible for secreting the primary spire callus that overlies the suture, rather than producing the columellar callus as was previously believed (Marcus and Marcus 1959). Belloliva and Calyptoliva combine a suite of shell, radular, and anatomical characters that is shared with either the Olivinae or the Ancillariinae. This raises the question of the distinctiveness of the two classically recognized subfamilies within the family Olividae. All species have paucispiral protoconchs with inferred limited larval dispersal, and many have extremely narrow distributions, sometimes endemic to a single guyot, or they show discrete geographical differentiation. New species: Belloliva iota sp. nov., Belloliva alaos sp. nov., Belloliva apoma sp. nov., Belloliva ellenae sp. nov., Belloliva obeon sp. nov., Belloliva dorcas sp. nov., Calyptoliva bolis gen. nov., sp. nov., Calyptoliva amblys sp. nov., Calyptoliva tatyanae sp. nov.

Flexopecten felipponei (Dall, 1922) is a non-commercial, seldom reported pectinid from the SW Atlantic Ocean. In this contribution we review its taxonomy, describe epifaunal species and their levels of encrustation, and discuss the composition of the macrobenthic assemblage where this scallop lives. Eighteen epibiont taxa were observed to live on the valves of these scallops. The most frequent and abundant epibionts on F. felipponei were serpulids, barnacles, and oysters. Although both valves were encrusted, the left valves had higher percentages of coverage. The benthic community contained 69 invertebrate taxa that generally characterize other mid-shelf bottoms between 37°S and 39°S. Eight pea crabs of the species Tumidotheres maculatus (Say, 1818) were found inside eight individuals of F. felipponei. Two other scallops had burrows of Polydora websteri Hartman, 1943. These were the first observations of these infestations on F. felipponei.

The extinction of many species of endemic land snails in French Polynesia because of the introduction of the carnivorous snail Euglandina rosea is a salutary lesson in hasty biological control undertaken without adequate scientific field trials. Fewer than 20 of the original 70 nominal species of the family Partulidae in French Polynesia survive. In 2004 surveys were carried out in nearly 70 of the valleys of Tahiti. All of the populations found were of Partula hyalina, the closely related Partula clara, or Samoana attenuata. No individuals of the Partula otaheitana/Partula affinis complex were found, yet P. otaheitana, together with Samoana burchi, still survive in many montane forest areas (over 1000 m altitude), while P. affinis persists on the Peninsula of Tahiti. Partula nodosa, with a previous distribution of just 7 valleys, has most likely been extirpated in the wild but persists well in captive populations. The species Partula filosa, Partula producta, and Partula cytherea (each previously inhabiting a single valley) are almost certainly extinct, as is Samoana jackieburchi.

Species of phyllidiid nudibranchs from Papua New Guinea (and other Indo-Pacific regions) are redescribed in this paper. A new species, Phyllidiella backeljaui n. sp., is described and compared with other species of the genus. External characters and internal morphology of the species studied have been examined in detail and illustrated, some of them for the first time such as Phyllidiopsis pipeki. In addition, new locations for Phyllidiella hageni and Phyllidiella zeylanica are reported from Papua New Guinea.

Five new species of aeolid nudibranchs are described based on specimens collected at several localities of the tropical eastern Pacific, from Isla Isabela, Nayarit, Mexico to Parque Nacional de Coiba, Panama. Three of the new species belong to the genus Cuthona Alder and Hancock, 1855, one to Eubranchus Forbes, 1838, and one to Cerberilla Bergh, 1873. All are distinct from other previously known species of these genera. An additional species, possibly belonging to the genus Herviella Baba, 1949 is not named because of the lack of adequate anatomical information.

The range of concentration of calcium carbonate in the shells of various freshwater gastropods was determined using ion chromatography. Individuals of Helisoma trivolvis (wild) were collected from three ponds in Pennsylvania and New Jersey; individuals of Physa sp. were collected from one pond in New Jersey; individuals of H. trivolvis (Colorado strain) and Biomphalaria glabrata (NMRI strain) were raised in the laboratory; and individuals of Pomacea bridgesii were purchased commercially. The concentrations of calcium carbonate (mean % by dry weight) of the shells were as follows: H. trivolvis (wild), 97.0; Physa sp., 97.8; H. trivolvis (CO), 97.6; B. glabrata, 98.8; P. bridgesii, 98.2. Our data support and validate the previous claim that snail shells are comprised of 95–99.9% calcium carbonate.

Population dynamics of the brackish water clam Corbicula japonica were examined in the Kiso estuaries (the Ibi-Nagara Estuary and the Kiso Estuary), central Japan, during the process of larval recruitment. Based on temporal variation in densities (sampling every 2 weeks for planktonic larvae, new settlers, and small individuals, sampling every month for large and commercially important individuals) from May 2001 to April 2004, we conclude that densities of large and of commercially important individuals were determined not by larval supply but by benthic processes. Density-dependent processes were detected between densities of new settlers and recruits. These processes, however, were detected for spring-summer cohorts, but not for autumn-winter cohorts. Spatial distributions of each cohort were almost the same within the Ibi-Nagara Estuary and within the Kiso Estuary, although cohorts were collected mainly in the middle to upper regions of the Ibi-Nagara Estuary but were collected in the upper region of the Kiso Estuary. A shift in an ontogenetic habitat within each cohort was detected in the Ibi-Nagara Estuary but not in the Kiso Estuary: New settlers and small individuals were collected in the upper region while large and commercially important individuals were collected in the middle region. The shift may be explained by tidal migration using byssal threads or by site-specific differences in mortality, although it was not clear why the shift was detected in the Ibi-Nagara Estuary but not in the Kiso Estuary.

Many gastropods, including limpets, periwinkles, and mud snails, detect and follow mucous trails. The stylommatophoran pulmonate snail Mesodon thyroidus follow conspecific trails in the field, potentially following in the direction they were laid, as has been demonstrated for other pulmonates. This study investigated whether individuals of M. thyroidus directionally follows conspecific trails, and whether substrate type or incline influences trail following. Trail following was quantified on plexiglas and glass surfaces at horizontal, vertical, and 45° inclines. On horizontal plexiglas surfaces, 36% of M. thyroidus followed a marker trail made by a conspecific (n = 11). On horizontal glass surfaces, 45% of the snails followed a marker trail (n = 20). On glass (all inclines combined) 75% of snails that followed a conspecific trail followed it in the same direction it was laid (n = 60). On plexiglas (all inclines combined) 86% of trail-following proceeded in the direction the trail was laid (n = 33). The difference in the results across the two substrates could indicate a behavioral reaction to the chemical difference of the substrates. Preliminary observations of tentacle movements and of the mucous trails indicate that previously laid trails can be detected before the foot of the following snail contacts the marker trail.

The diversity of freshwater mussels in Colorado is low compared to other regions of the U.S.A., with only three extant species (down from seven a century ago). The western ridged mussel (Gonidea angulata) occurs in Pacific Coast drainages from British Columbia to California and eastward to Idaho and Nevada. It has been reported from Colorado based on a single museum specimen from Clear Lake, representing a significant range expansion for this species. During extensive recent surveys, I was unable to pinpoint this locality and regarded it as questionable. Examination of the specimen and locality data indicated this specimen was collected from Clear Lake, Lake County, California.