Major papers on pyramidellid protoconchs, larval development, and larval ecology are reviewed, partly with illustrations. Larval shell coiling (including hyperstrophy and heterostrophy) is discussed. A-, B-, and C-type protoconchs are figured and distinguished. Those of species in the Baltic and northwestern France have been used to infer modes of larval development. The reliability of many of these inferences is questioned. Egg, embryo, and veliger morphologies, functions and terminologies are then discussed, including confusions of the terms “egg” and “capsule.” The pigmented mantle organ or gland (“PMO”) is briefly reviewed. Previously published data on the eggs and larvae of Brachystomia “scalaris” (Macgillivray, 1843), of“Turbonilla” cummingi Hori and Okutani, 1997, and of “Odostomia columbiana Dall and Bartsch, 1907”, are reviewed in detail with some new interpretations. In the first of these species, egg size variation is possibly salinity-induced and may cause variation in mode of development. Alternatively, different species may be involved. In the second named species, lecithotrophy straddles intracapsular metamorphosis sympatrically. In the third species, some of its unusual features may have been induced by low temperatures. “Mid-water metamorphosis” is then discussed. It is concluded that species with A-type protoconchs may be constrained to planktotrophy.

The genus Boonea Robertson (1978), ectoparasitic on mollusks, consistently has a B-type protoconch morphology thought by Thorson (1946) to indicate planktotrophy in other pyramidellid genera. Studies in the laboratory of the eggs and larval development of Boonea seminuda (C. B. Adams, 1839), the type species, B. bisuturalis (Say, 1822), and B. impressa (Say, 1822) on the eastern North American seaboard confirmed planktotrophy. The egg diameter range there was 68 to 80 µm. Boonea bisuturalis had been reared through metamorphosis using algal cultures (Robertson 1967; Leibowitz 1979 [unpublished]). The developmental stages are newly illustrated here. Boonea seminuda and B. bisuturalis have different teleoconch sculptures, similar but different spermatophores, and are closely related. Northern B. bisuturalis and southern B. impressa are allopatric and hybridize or intergrade conchologically in a cline between Long Island Sound and Chesapeake Bay. One population of B. “impressa” had been found to be lecithotrophic on the Texas coast, at Port Aransas (White et al. 1985). A second Texan population, at Galveston, is shown here consistently to undergo intracapsular metamorphosis. The eggs were reared to hatching crawlers in the laboratory. The Galveston protoconch sizes and morphologies are the same as at North Carolina, but eggs from Galveston were much larger (212 to 236 µm in diameter). Durations of intracapsular development through metamorphosis and the pelagic larval stage in laboratory B. bisuturalis were virtually the same (respectively 15 to 20 and 16 to 20 days). In the three species, egg sizes greatly affect oviposition to hatching times, hatching sizes, and whether or not there is planktotrophy. Egg sizes do not affect oviposition to metamorphosis times, or protoconch sizes. North Carolinian and Texan B. impressa teleoconch sculptures and spermatophore sizes differ slightly. There could be a wide and continuous intraspecific range of conchological and/or reproductive variation, or allopatric poecilogony, or a chemically-induced ecotype, or (as seems most likely) one or more as-yet unnamed sibling species in the Gulf of Mexico. Regardless, this appears to be the first known exception to the “shell apex theory” (Thorson 1950). Everywhere, B. “impressa” is a serious pest of Crassostrea virginica (Gmelin, 1791). Some new data on Boonea systematics, adult ecology, and life history are presented. “Boonea” scymnocelata Pimenta et al. (2009), from Brazil, is not a Boonea because it has a C-type protoconch; its teleoconch is convergent with that of B. seminuda.

C-type protoconchs have been thought always to reflect a “direct” or short pelagic development, an idea deriving from Thorson's (1946) study of the early development (besides planktonic veligers) of only one pyramidellid species. The small-shelled genus Fargoa Bartsch (1955), some ectoparasitic on serpulid polychaetes such as Hydroides, apparently uniformly has C-type protoconchs. The eggs and early larval development of Fargoa dianthophila (Wells and Wells, 1961) (shells < 1.8 mm) and F. bartschi (Winkley, 1909) (< 4.0 mm) were studied in the laboratory at Woods Hole, Massachusetts. The eggs were only 53 to 57 µm and 55 to 60 µm in diameter, respectively, and as would be expected from eggs this size both species are definitely planktotrophic. Few other pyramidellids or other “opisthobranchs” lay eggs this small, and the single Brachystomia (Monterosato, 1884) species studied by Thorson (1946) was also planktotrophic. The protoconch diameters of F. dianthophila and F. bartschi are, respectively, about 260 to 315 µm and about 210 to 230 µm, i.e., surprisingly large. This variation parallels neither the nearly uniform egg size nor the disparate adult shell sizes. No attempt was made to rear the larvae in the laboratory because there were only a few newly hatched veligers and these protoconchs indicated much growth in the plankton. These Fargoa veligers may remain planktonic for longer times than planktotrophic Boonea Robertson (1978). One protoconch, an egg capsule containing a late blastula, and a newly hatched swimming veliger are illustrated. Small pyramidellids appear to lay the smallest eggs, but this seems not to be true of other “opisthobranchs.”

Nucella lamellosa (Gmelin, 1791) is a phenotypically plastic species that preys on barnacles and occurs intertidally and subtidally along the north-eastern Pacific coast. This laboratory experiment tests the hypothesis that daily episodes of emersion impose a greater stress than daily episodes of limiting food in N. lamellosa. In this experiment, individuals of N. lamellosa were housed in containers with a rock covered with barnacles. In one experimental treatment, I removed snails from their barnacle-covered rocks and placed them on a counter for five hours each day. In another treatment, I placed the snail-and-rock assemblage on a counter for five hours each day. In a final experimental treatment, I kept the snails submersed, but placed the barnacle-covered rocks in an empty sea table for five hours each day. A control treatment kept individuals constantly submersed with continuous access to food. To account for the effect of handling the snails, individuals in a manipulation control were picked up and then immediately returned to their rocks. When individuals of N. lamellosa were removed from the water without their barnacle-covered rocks, they ate significantly less than snails in either control group and significantly less than the snails that were constantly submersed but without food for five hours a day. This result suggests that daily episodes of emersion are more stressful than daily episodes of limiting food.

Aequipecten tehuelchus (d'Orbigny, 1846) is a commercial resource, distributed from Rio de Janeiro (Brazil) to Golfo Nuevo (Argentina), on sandy and muddy bottoms. In Argentina, the major banks of exploitation are located in the gulfs of San José and San Matías. This study represents the first ecological study of A. tehuelchus in shelf waters off Buenos Aires, Argentina. Eighteen epibiont taxa were registered on the individuals analyzed. Polychaetes were the most frequent epibiotic organisms (82%), including Serpulidae (Rafinesque, 1815), Phyllochaetopterus socialis (Claparède, 1869), Idanthyrsus armatus (Kingberg, 1807) and Chaetopterus antarcticus (Kingberg, 1866). Ostrea puelcheana (d'Orbigny, 1842), Balanus cf. amphitrite (Darwin, 1854) and solitary ascidians were found on less than 30% of the sampled individuals. Bryozoa and Porifera were scarcely represented. Phyllochaetopterus socialis, I. armatus and Balanus cf. amphitrite were most frequent on the upper (left) valve. This study nearly doubles the number of epibionts identified and mentioned on A. tehuelchus in Patagonian Gulfs. Three individuals of the commensal pea crab Tumidotheres maculatus (Say, 1818) were found inside three different specimens of A. tehuelchus. One left scallop valve was burrowed into by the parasitic polychaete Polydora (Bosc, 1802).

We examined variation in dietary specialization of Enteroctopus dofleini (Wülker, 1910), the giant Pacific octopus, from Puget Sound to the Aleutian Islands, as represented in midden remains. Dietary specialization was measured from midden contents as: species richness (R) and Cardona's niche breadth (regional indices), and proportional similarity of a midden to the regional sample (an individual index). We found an influence of items per midden and prey species maximum size on these indices. In Puget Sound, middens and common prey species were large, richness, R = 21 species, and individuals specialized more often than in other areas, typically on large prey species. In Saanich Inlet, British Columbia, middens were smaller, R = 9 species, and the large crab Cancer productus was common in nearly all middens, such that the population specialized rather than the individual. In Prince William Sound, Alaska, middens contained fewer individuals of smaller prey species, R = 52 species, and diet was generalized at both the population and the individual levels. Cardona's niche breadth ranged from . 11 to . 14 except in the Aleutian Islands, Alaska where it was higher (.30). Most individual E. dofleini were generalists, and dietary species richness was very high (R = 69 species overall). Specialists within a generalist population were common only where middens and dominant prey were both large.

Previously-published mate-choice experiments have uncovered significant prezygotic reproductive isolation between South Carolina populations of Physa acuta (Draparnaud, 1805) and P. pomilia (Conrad, 1834). Here we report the results of similar tests returning no evidence of such barriers between an Alabama population of P. pomilia and three separate populations of P. acuta, two from Alabama and one from South Carolina. However, heterogametic copulations did demonstrate both a significant sex bias and a significant size bias. The smaller P. acuta was more likely to copulate in the male role and hence less exposed to any potential fitness decrements due to the reduced viability and sterility of the hybrids produced. Our observations on defeated mating attempts suggested that P. acuta may be more aggressive than Alabama P. pomilia in mating contests (its smaller size perhaps contributing to greater agility) and hence more likely to prevail in the male role. The absence of a sex bias in our previously-published mate-choice observations involving South Carolina P. pomilia and P. acuta may be attributable to our use of size-matched snails, which equalized the agility of the prospective copulants, thus perhaps prolonging the mating contests, and ultimately lessening the likelihood that any mating took place at all.

Anthropogenic introduction of steroidal estrogens and synthetic estrogenic compounds to aquatic environments has increased interest in assessment of the endocrine-disrupting effects of these compounds on aquatic organisms, including mollusks. For gonochoristic freshwater snails in the family Pleuroceridae, little is known about the spatial and temporal variation in population sex ratios or potential relationships between sex ratios and exposure to estrogenic compounds. Population sex ratios of Leptoxis (Rafinesque, 1819) spp., were evaluated within the Shenandoah River watershed (Virginia, U.S.A.), where agricultural operations are a source of estrogenic compounds to streams, and in four other river basins in Virginia. Proportions of females varied among streams within the Shenandoah River watershed, with overall mean proportions from four sampling periods ranging from 0.46–0.87. Sex ratios were consistently female-biased at nine of fifteen stream sampling sites. There was little within-site variation across generations of snails or when the same generation was examined in two different seasons. Proportions of females were not directly related to in-stream concentrations of estrogenic compounds or watershed densities of agricultural operations, but were negatively related to mean summer temperature at the sampling sites. Population sex ratios of Leptoxis spp. were female-biased at two of six sites in the Shenandoah River and one of five sites outside the basin. At the river sampling sites, proportions of females were only related to summer-specific conductivity. Overall, results suggest that site-specific factors can affect population sex ratios of Leptoxis spp. However, until more is known regarding mechanisms of sex determination and sexual differentiation in gastropods, population sex ratios should not be used as indicators of potential biological effects of estrogenic compounds.

The land snail genus Eobania P. Hesse, 1913 in Croatia consists of four taxa: Eobania vermiculata vermiculata (O.F. Müller, 1774), E. v. pelagosana (Westerlund, 1894), E. v. figarole (Rensch, 1928) and E. v. kamenensis Berberović, 1963. Only E. v. vermiculata and E. v. pelagosana have been included in this study. The mean shell diameters (D) of the 13 samples ranged from 19.99 mm (sample from the island of Sušac) to 31.78 mm (Šibenik, seaside) and the mean shell height (H) from 17.31 mm (Sušac) to 25.66 mm (Island of Šolta). Shell morphology confirms that all island populations are smaller with examples of nanism on outside islands of Palagruža and Sušac. However, molecular analysis (16S rDNA and COI sequence data) showed no significant differences between the South Adriatic population from the mainland and islands, thus providing no molecular evidence for classification of a single E. vermiculata species into separate subspecies within the investigated area. The observed differences might possibly be attributed to ecological influences. The population with the largest average shell size was approximately 1.5x larger than the population with the smallest average size.

In the northern Santa Rita Mountains, Pima County, Arizona, there are three named species of the helminthoglyptid landsnail Sonorella Pilsbry, 1900: Sonorella magdalenensis (Stearns, 1890), S. walkeri walkeri Pilsbry and Ferris, 1915, and S. rosemontensis Pilsbry, 1939. Of these taxa, Pilsbry (1939) originally named S. rosemontensis based on shell characters alone. Later, he dissected and described the reproductive organs from a specimen preserved in alcohol that was collected at a location different from the type locality. Subsequently, Walter B. Miller collected two snails, calling them S. rosemontensis, because they were collected at Pilsbry's S. rosemontensis locality. He noted that their male genitalia did not resemble those described by Pilsbry; rather, they closely resembled those of S. w. walkeri. Our examination of shell and reproductive anatomies of snails from the S. rosemontensis type locality near the north end of the Santa Rita Mountains, as well as specimens in the Santa Barbara Museum of Natural History collection lead us to conclude that snails previously referred to as S. rosemontensis are synonymous with S. w. walkeri, and that in his original description of the reproductive anatomy of S. rosemontensis, Pilsbry mistakenly dissected a specimen of S. magdalenensis.

The Madrean Archipelago Biological Assessment (MABA) “bioblitz” expedition to Sierra de la Madera (Oposura) near Moctezuma, Sonora, Mexico from 29 July—7 August 2010 included a land snail inventory. Five people searched for both macro- and microsnails in five sites in foothills thornscrub, oak woodland, and pine-oak forest (1225–2080 m elevation) and found 347 individuals of 18 species or forms. Macrosnails included a Sonorella Pilsbry, 1900 species (N = 5) found at four sites, a succineid species (N = 3) from two sites, and one philomycid slug. Micromollusks (< 6 mm) included representatives of seven families. The vertiginid genus Gastrocopta Wollaston, 1878 included eight species/forms. Vallonia perspectiva Sterki, 1892 was the most abundant species (N = 123). This collection adds four species to the 59 previously reported for the state. Seven forms from this southern “sky island”, including the Gastrocopta ashmuni group (=Immersidens ashmuni Pilsbry and Vanatta, 1900) and Sonorella, are characteristic of the Southwestern Mollusk Province (SWMP). Collecting land snails in Sonora has been sporadic because of the difficult terrain and remote locations. Additional efforts and locations should add many more species and clarify biogeographical affinities of this rugged area.

The Family Lymnaeidae is comprised of large aquatic snails that are intermediate hosts of parasitic flukes. In the present study, radular morphology, teeth length, and tooth formula of field-collected lymnaeid snails including Galba truncatula (Müller, 1774), Lymnaea stagnalis (Linnaeus, 1758), Radix auricularia (Linnaeus, 1758), and Radix gedrosiana (Annandale and Prashad, 1919) were investigated. The conical and dextral freshwater snails were collected from their natural habitats in West Azerbaijan province, northwestern Iran, in fall 2010. The snails were rinsed, measured, and taxonomically identified. The radula of all specimens was extracted and stained using Mallory II. Besides the morphological variations, the mean length of radular teeth significantly increased with the body size of the examined lymnaeid snails. Morphometric investigation indicated that the mean length of lateral (L) (427.86 ± 6.9 µm) and marginal (M) (427.82 ± 6.86 µm) radular teeth of Lymnaea stagnalis differed significantly from those of other examined lymnaeid snails. The average number of radular M teeth and L teeth were the highest in R. auricularia and L. stagnalis, respectively. The specimens with smaller body size had the most transverse teeth rows (G. truncatula, 115.6 ± 3.7 µm). It was concluded that radular teeth morphology and morphometry within lymnaeid species could be one of the character sets for classification of lymnaeid snails.

During a recent survey a small population of Quadrula mitchelli (Simpson, 1895), a species thought to have been extinct, was discovered in Texas. In total, 7 live individuals were collected from the Guadalupe River near Gonzales, Gonzales County, Texas. Our finding represents the only known population for this species in Texas and the first record of live specimens in over 30 y, which is significant because this species is currently under review for protection under the Endangered Species Act.

Glochidial morphology of two unionid species of the genus Schistodesmus Simpson, 1900 from Lake Poyang (China), Schistodesmus lampreyanus (Baird and Adams, 1867) and S. spinosus Simpson, 1900 were studied for the first time under light and scanning electron microscopy. Glochidial characters, including shape, size, hook, sensory hair tufts and exterior minute sculpture, are presented and compared with some allied species for the identification of glochidia. Schistodesmus has small and ovate subtriangular glochidia with styliform hook. Glochidia of the two species of Schistodesmus Simpson, 1900 differed from each other in relative abundance of microstylets and micropoints, and valve sculpture.

In situ observations of the cock-eyed squid Stigmatoteuthis dofleini (Pfeffer, 1912) were recorded in high definition video at 439 m depth off the eastern seaboard of Japan during a survey by the ROV HyperDolphin. Novel behaviors including a quick body turn (ratcheting) were observed and are reported here with discussion on their ecological significance.