Schistosomiasis remains a public health problem in the developing world. Biomphalaria alexandrina is the intermediate host of Schistosoma mansoni, with a widespread distribution in Egypt. In Egypt molluscicides have been important, but otherwise molluscicides have been of minor significance. They may, however, become important now that WHO talks about eradicating schistosomiasis in some countries and that WHO has finally accepted that snail control is important.The present study investigated the different effects of three commercial herbicidical compounds, Butralin (as Amex 48% EC), glyphosate isopropylammonium (Herphosate 48% SL) and Pendimethalin (Stomp 50% EC) on B. alexandrina. All three compounds were found to have a molluscicidal effect, with Pendimethalin the most toxic over the examined range of concentrations. In addition, at sublethal concentrations, these compounds reduced growth rates and reproductive output (numbers of eggs laid) in exposed B. alexandrina, and it reduced viability of those eggs. Interpretion of assay data was supported by histological changes in the digestive and hermaphrodite glands of snails exposed at a range of concentrations. Moreover, the three compounds were also shown to rapidly (with three hours exposure) induce a toxic effect in miracidiae and cercariae of Schistosoma mansoni. It can be concluded that the three herbicidical compounds have molluscicidal and antihelminth properties.

Lithic particles are a common feature in the digestive tract of freshwater snails. Their role in the digestive processes has been demonstrated in some microphytophagous and detritivorous species, as they enhance growth, assimilation and reproduction. It has been suggested that they could have the same function in Pomacea canaliculata, a macrophytophagous apple snail with powerful jaws and radula, a strongly muscular and cuticularized gizzard and high levels of enzymatic activity. Our aims were to investigate the occurrence of lithic elements in the digestive tract of P. canaliculata snails from natural populations through the analyses of digestive contents, as well as the effect of size and availability of lithic particles on growth and growth efficiency through laboratory experiments. Lithic particles are very common in the digestive tract of P. canaliculata from natural populations and from laboratory aquaria if they are available in the immediate environment. Such particles are not retained or concentrated differentially in the stomach and they are apparently totally lost in less than four weeks if the supply is interrupted. The frequency of plant material and lithic particles increases from mouth to anus indicating that the retention time increases in the same way. Sand and plant material frequently co-occur in the intestine and in the stomach indicating that both are ingested together. Ground marble had negative effects on the growth of P. canaliculata probably due to the sharp edges and pointed ends of these particles. The availability of natural lithic particles (sand) had a positive effect on growth and also a synergic interaction with the availability of food. The growth efficiency was 25.2% higher when sand was available than when it was absent. These effects were more marked in juvenile females than in juvenile males. Our results indicate that growth rates may be underestimated under laboratory conditions if lithic particles are not supplied regularly and that their presence should be standardized to allow reliable comparisons between studies. Our results also indicate that the effects of food availability and plant palatability on the growth of P. canaliculata may be modulated by the presence of lithic particles and this may in turn affect the outcome of interactions between apple snails, other snails and macrophytes.

Pupilla alluvionica Meng & Hoffmann, 2008 is an extant land snail species known until now only from a few sites in the Russian Altai Mountains. We have now identified it in fossil loess assemblages of Early-Middle Pleistocene age at three Central European sites. Fossil materials match those of Altaian populations, being only slightly smaller in mean shell width. In addition to the details of the locations and biometrics of these fossil finds, we list the faunas associated with P. alluvionica in the deposits. These are compared with the ecological conditions and associated faunas of living populations from the Altai. Pupilla alluvionica is a typical inhabitant of xeric habitats: steppes with rocky limestone outcrops. This matches the known habitat preferences of associated species in the fossil deposits that are typical of open loess steppe.

The hatching of an embryo from its egg is a crucial point in its development. This is the moment that decides whether the animal will be able to emerge and survive or whether it will remain trapped and die. Cephalopods usually produce enzymes in a system of glands known as the Hoyle organ, which weakens the chorion and enables hatching. In addition to this chemical approach, four cephalopod genera develop a terminal spine to further support the hatching process.

The presence of such a spine has been mentioned for the well-known cephalopod species Euprymna scolopes. However, little is known about either its structure or its cellular details. Our present results indicate that the spine consists purely of musculature, and no intermediate connective tissue was observed. No nerves were detected within the spine, although nerve fibers are present within the surrounding epithelium and dermal muscle layer, indicating that the spine stretching is controlled by this dermal musculature.

Our data show that the spine of Euprymna is similar in its composition to those of the other three cephalopod genera in which a spine has evolved. However, we found morphological differences in the spine tip and in a collagenous layer located between the spine and the normal epithelium. It remains unclear why two completely different but synergetic systems for hatching, the glandular Hoyle organ and a spine, exist in some, but not all, cephalopod genera.

The brood sex ratio of the apple snail Pomacea canaliculata is highly variable among parents in areas where it has been introduced. Such variation in the sex ratio may reflect variation in the source population, or it may have stemmed from the mixture of multiple source populations with different sex-determining mechanisms. To distinguish these hypotheses, the sex ratios of F₁ (hatchlings from wild-collected egg masses) and F₂ snails (produced from crosses of the F₁ snails) from three sites in the native range in Argentina were studied. The sex ratios of the F₁ snails were not significantly different from 0.5, although there was a slight but significant difference among populations. The F₂ broods from intra-population crosses also lacked variation in the sex ratio. However, the sex ratios in F₂ broods from inter-population crosses were highly variable, from 0 (all females) to 0.84 (mostly males). Thus, the large variation in the sex ratio in areas where P. canaliculata has been introduced is probably due to the mixture of source populations.

Turritella duplicata (Linnaeus, 1758) is a marine suspension-feeding gastropod found in shallow-marine and tidal flat environments throughout Southeast Asia and the Indo-West Pacific. It was studied on a tidal flat in the national park of Nopparat Thara in the district of Krabi, southern Thailand. Turritella duplicata was found primarily in the lower intertidal zone, and 90 specimens were gathered and measured. Their geographical positions on the flat were mapped, revealing zonations in population distribution, both parallel and perpendicular to the shore-line. The size distribution of the shells indicates that the population consists exclusively of adults. δ¹⁸O sclerochronology performed on three shells shows variations of up to 1.5‰ associated with seasonal changes in water parameters, suggesting longevity of about three years and seasonally controlled growth rates. The absence of juveniles and observed population distribution coupled with the sclerochronological data suggest that reproduction occurs in early spring, and that the population represents three cohorts approximately one year in age and older. Migration to deeper water during other seasons cannot be ruled out. Smaller individuals were preferentially found on the inner tidal flat, and individuals older than two years preferentially colonised the outer tidal flat. The carbon isotopic composition of the analysed shells partially tracks these life stages, suggesting that metabolic “vital effects” are influencing the δ¹³C of the shells.

Predator-prey interaction, especially drilling and shell-breaking predation pressure, caused significant evolutionary changes within these predator-prey communities. Although temporal trends are well understood in prey assemblages, studies to trace such changes within taxonspecific clades up to Recent times have been rare. Here, we studied both the drilling and shell-breaking predation on Recent terebrid gastropods from the Indian subcontinent and compared the results with a newly updated, global database. The major part of our data came from a large collection reposited in the archive of the Zoological Survey of India in Kolkata for more than 100 years.

Detailed analyses of this study based on a newly raised, global database revealed the following findings: (1) Drilling frequency (DF) of Indian terebrids was low, but consistent with the DF of only available but limited data provided by Vermeij et al. (1980). In comparison, peeling frequency (PF) in Indian terebrids appeared to be highest in the world; (2) DF showed latitudinal variation, that is, higher incidence of drilling occurred in higher latitudes; no such pattern emerged from the PF data; (3) drillholes were site-stereotyped, which suggested that Recent naticid drillers were escalated; (4) shell ornaments failed to protect against durophagy; (5) shell shape and thickness had different impact against different modes of predation. While slender and thicker shells were almost immune to drilling predation, no such relation existed for peeling predation; (6) on the other hand, body size appears to have evolved as anti-predatory traits in Recent terebrids. Larger species had low DF and high PF values; (7) temporally, DF showed fluctuating pattern, with modern values showing declining trend. This was perhaps due to increase in body size and behavioural change of the terebrid gastropods. Unfortunately, no peeling frequency data for this clade was available from the fossil record.

The blood clam, Tegillarca granosa, is widely distributed along the coasts of the Indo-Pacific region, providing an excellent opportunity to study gene flow in sessile marine mollusks. In the present study, amplified fragment length polymorphism (AFLP) DNA markers were used to analyze the genetic structure of five blood clam populations. Genetic differentiation (Gst) and Nei's genetic distances between population pairs were found to range from 0.0245 to 0.0785 and 0.0398 to 0.1125, respectively. An AMOVA analysis showed that 89.09% of the genetic variation occurred within populations and only 10.92% occurred among populations, indicating a high degree of genetic homogeneity, probably due to considerable gene flow (average Nm = 7.1853) among populations. Cluster analysis using the unweighted pair group method average (UPGMA) showed that geographically closer populations were clustered, suggesting isolation by distance, which was further supported by a significant positive correlation between Gst and logit transformed geographic distance through a Mantel test and reduced major axis regression (r = 0.77, p < 0.05). The evident isolation by distance observed among blood clam populations along the Pacific coast of Asia is likely to be a consequence of both the passive larval dispersal carried by the South China Sea Warm Current and the genetic homogeneity caused by aquaculture-associated human activities.

Patagonia and the Tibetan Plateau both harbor various freshwaters with relatively low temperatures. Pulmonate freshwater gastropods are widely distributed in these water bodies. Both regions, however, also possess a number of geothermal hot springs. Such springs might have served as refugia for freshwater taxa during the Pleistocene. In the present study, two hot spring systems, one in Patagonia and one at the Tibetan Plateau, were examined. Individuals of Chilina patagonica (in Patagonia) as well as Radix cf. auricularia and Gyraulus sp. (at the Tibetan Plateau) were found living in the warm water. These taxa typically live at much lower water temperatures. At the Patagonian hot spring system, gastropods occurred continuously from warm to cold water. Analyses of mitochondrial DNA sequence data revealed very close relationships of Tibetan Plateau hot spring gastropods to cold water populations. Acclimatization and not adaptation is thus probably the main thermal adjustment process involved. Given these findings, it is plausible that hot springs have served as glacial refugia for these freshwater gastropods.

The Lepetidae are currently assumed to be represented by only one valid species in the Magellan region: Iothia emarginuloides (Philippi, 1868), of which Tectura (Pilidium) coppingeri Smith, 1881, and Iothia coppingeri magellanica Linse, 2002, were regarded as synonyms. The extant records of this species are scarce, although they suggest a wide distributional range in the Pacific Ocean, from off Concepción (36°S) to the Beagle Channel (55°S), and a restricted distribution in the Atlantic Ocean, where the species is only known from the Malvinas / Falkland Islands and Isla de los Estados (about 54.5°S). This study provides new information on the occurrence of the genus Iothia in the Magellan region, including morphological, anatomical and molecular evidence. The synonymy of Tectura (Pilidium) coppingeri, Iothia coppingeri magellanica and Iothia emarginuloides is ratified. The species is properly redescribed and figured, and its intraspecific variability discussed, particularly regarding its relation with depths. Furthermore, the distribution of this species in the southwestern Atlantic is extended north to San Matías Gulf (about 41°S). Iothia megalodon Warén, Nakano & Sellanes, 2011, previously known from deep waters off Concepción (36°S), is here reported for the first time for the Magellan region. Its finding in shallow waters from the Beagle Channel greatly extends its distribution both latitudinally and bathymetrically.

Physa acuta (Gastropoda: Heterobranchia: Physidae) is a freshwater snail commonly found in North American rivers, streams and ponds. Despite its widespread distribution across the United States, it is generally regarded as an invasive species. As a result, P. acuta receives no attention during conservation management inventories. However, data suggest that P. acuta may be a native to North America rather than to Europe, where it was first described. First, the fossil record in Europe lacks P. acuta, whereas North America is home to numerous fossils of members of the acuta species group. Second, breeding studies among P. acuta and North American taxa from the acuta species group show no evidence of pre- or postzygotic isolation. Third, investigations of reproductive anatomy between P. acuta and other nominal species of the acuta species group are indistinguishable, leading investigators to synonymize taxa. Finally, phylogenetic data do not support the distinction of P. acuta from its North American congeners of the same species group. Together, these data support our case that P. acuta is a North American native.