The effects of temperature acclimation and acute temperature variation on oxygen consumption were determined for the pleurocerid snail Lithasia obovata (Say, 1829), a prosobranch restricted to the Ohio River and its tributaries' main stems. Snails were divided into two treatment groups and acclimated to constant temperatures (either 15 or 25 °C). Following acclimation, oxygen consumption rates for each animal were recorded at both 15 and 25 °C. Oxygen consumption rates did not differ between the two treatments at either temperature. Lithasia obovata exhibits no metabolic temperature compensation, as determined by acclimation Q₁₀ (Q_10acc). Because of the thermal inertia of the Ohio River (which does not change more than 1 °C day¹), L. obovata is not exposed to rapid, large changes in water temperature and, thus, has little need for adjusting to short-term changes in ambient temperatures. We then examined the published literature and compared the acute Q₁₀ and Q_10acc values of L. obovata and other freshwater prosobranch snails to those of freshwater pulmonate snails. Acute Q₁₀ and Q_10acc values for pulmonates are lower than those exhibited by L. obovata and other prosobranchs; this result suggests that pulmonates have a greater compensatory capacity in response to both seasonal and diurnal temperature fluctuations. In addition, we compared the current geographic ranges of both gastropod groups in North America. Many pulmonates currently have considerably larger geographic ranges. Larger geographic ranges and greater compensatory capacities are important attributes in light of anticipated climate change impacts on freshwater ecosystems. Our results suggest that compared to pulmonates, North American freshwater prosobranchs generally are more at risk from additional environmental stresses arising from a warmer climate.

A major taxonomic problem around the genus Megalobulimus Miller,1878, the largest land snails in the Neotropics, is plasticity of conchological characters. Here we re-describe Megalobulimus leucostoma (Sowerby, 1835) and describe two new species of Megalobulimus from Southern Peru, Megalobulimus tayacajus sp.nov. and Megalobulimus inambarisense sp.nov. These descriptions are based on both conchological and soft anatomical characters. Megalobulimus leucostoma is characterized by the presence of a retractor muscle with two insertions to the buccal mass, two small bulges on pre-rectal valve, and a geographical distribution appears limited to Cusco. Megalobulimus tayacajus sp.nov. is characterized by the presence of a retractor muscle that divides near the buccal mass, two lobed bulges on pre-rectal valve, and to date, has been found only in Huancavelica. Megalobulimus inambarisense sp.nov. is characterized by the presence of a retractor muscle with one insertion to the buccal mass, two big bulges on pre-rectal valve, and a distribution appears limited to Puno. The digestive system appears to serve as useful characters to discriminate these species and, when combined with shell and reproductive characters, may help to understand better the evolution and ecology of these snails.

Populations of Mytilus edulis complex were studied from 13 stations located at three areas of the Baltic Sea (the Gulf of Gdańsk, Poland; Tvärminne area, Finland; Trosa Archipelago, Sweden) and the Skagerrak sound (Kristineberg, Sweden). The main purpose of the study was to document the occurrence of intersexuality along longitudinal salinity change using squash and histology for comparative reasons. Intersex was identified in all four geographical areas at an average frequency of 1.8%. Squash technique revealed the highest intersex frequency in the Gulf of Gdańsk (up to 6.25%) whereas histology examination did so in the Kristineberg area (up to 10%). In the Tvärminne area and in the Trosa Archipelago the average frequency of intersex did not exceed 2% regardless of the technique used; this suggests a natural induction of the phenomenon. Statistically significant spatial differences in intersex frequency were confirmed for mussels inhabiting polluted hotspots in the Gulf of Gdańsk and at the west coast of Sweden (Kristineberg). Therefore, for these localities artificial induction of intersexuality as a consequence of adverse environmental threats (pollution, parasite outbreaks) is further suggested. Furthermore, squash technique - being less sensitive in identifying intersex when compared to histology - is not recommended for mussels with severe reproductive impairments making a proper analysis of gonads impossible. Intersexual individuals were also characterized by less developed gonads and lower gonado-somatic index (GSI) than males and females. Significantly lower GSI revealed less energy allocation towards reproduction in populations from the Trosa Archipelago and Tvärminne area in comparison to those from the Gulf of Gdańsk and from Kristineberg.

Invasion of the bryozoan Membranipora membranacea to the Gulf of Maine provided an additional prey resource to the dorid nudibranch Onchidoris muricata (Müller, 1776). We examined prey choice based on past diet history and compared growth and reproductive output among laboratory-reared O. muricata on exclusive bryozoan diets of M. membranacea and the native, historically preferred prey, Electra pilosa. Adult nudibranchs were collected from Cape Neddick, York, Maine for the prey choice experiment and post-metamorphic juveniles were collected from Jaffery Point, Newcastle, New Hampshire for the growth and reproduction experiments. Nudibranchs were laboratory reared under controlled conditions for up to 10 months until completion of spawning. Growth was monitored biweekly, and reproductive performance was assessed with a weight-adjusted dimensionless reproductive index (ΣRI) of each individual's spawn summed over the reproductive period. Prey choice experiments showed nudibranchs tended to select prey based on prior feeding history. Diet influenced reproductive output: nudibranchs fed E. pilosa had larger first spawn, more total spawn, and larger average spawn, as well as higher reproductive effort. Diet did not influence weight-specific growth rate, maximum body size, or pre-spawn body size. Since the temporal abundances of these bryozoan prey differ, the predator benefits by consuming the novel prey when the native prey is rare. With the increased awareness of invasive species in communities, we suggest studies need to consider predator-prey paradigms that include the seasonality of non-native prey to gain an understanding of the influence these organisms have on native predator population dynamics.

The geographic distribution of Octopus mimus Gould, 1852 is unclear, as most records are restricted to coastal localities of Peru and Chile, and some references have mentioned its presence off Central America. It is unknown whether this octopus is found off Ecuador as two previous unpublished records have suggested. The aim of the present study is to identify genetically the main octopus captured in a marine protected area known as Reserva de Produccion Faunistica Marino-Costera Puntilla de Santa Elena (REMACOPSE) off the Santa Elena peninsula, Ecuador. Samples collected from the local fishery were used to test the presence of this species based on the sequences of three mitochondrial markers and using a Bayesian approach. The phylogenetic analysis confirms that O. mimus inhabits the REMACOPSE. The results also indicate that the octopus specimens captured in the fishery from this marine protected area, are more closely related to O. mimus specimens from Central America than those from South America. The genetic identification of two groups of O. mimus could be associated with the different marine environmental conditions of the two biogeographic provinces. The finding in this study represents an important step for posterior research on the biology and fishery of octopus in Ecuador.

Based on museum specimens and zooarchaeological material recovered by us, we note the historic presence of a population of sinistrally coiling Partula gibba Férussac, 1821 on the island of Guam. A single extinct population of this species is also known on an island > 150 km to the north. Hence, given the absence of sinistral populations on intervening islands and lack of indigenous cultural transport, we suggest that sinistrality independently evolved at least twice in P. gibba, the only species of Partula Férussac, 1821 outside of Polynesia to regularly display reverse coiling.

Octopus localize their drill holes on prey but it remains unclear how this is accomplished. Asymmetrical prey such as snails and crabs would provide cues to the octopus but the nominally symmetrical cowry presents a unique drill hole localization scenario. To investigate how octopus drill cowries we collected their shells from octopus middens in Bonaire and surveyed drilled specimens in shell collections. Cowry drill holes were predominantly localized to the ventral-posterior-lateral region of the shell, the attachment point of the columellar muscle. Cowries with multiple drill holes suggest a trial-and-error learning process leading to localization. Further studies with naïve octopuses are proposed to determine the role of learning in this feeding behavior.