The deep-water cephalopod Nautilus pompilius pompilius Linnaeus, 1758 may benefit from detecting potential signals such as mechanical and acoustical stimuli in its dark habitat where visual information is often limited. Here we examined whether specimens of chambered nautilus are capable of responding to waterborne vibration—a sensory mechanism that has yet to be investigated. We measured the ventilation rate of animals responding to a vibrating bead that produced a range of displacements and velocities. We found that nautiluses do indeed respond to underwater acoustical stimuli, decreasing their ventilation in the presence of a vibratory stimulus. Vibrations resulting from large-bead displacements and high source-velocities caused the animals to decrease their ventilation the most. Stimuli <20 cm from the animals caused a further reduction in their ventilation rates than those at greater distances. These nocturnal animals, living in dark conditions where visual information is often limited, may benefit from including vibrations in the suite of stimuli to which they can respond.

In natural settings octopuses use their arms and suckers in a variety of dexterous manipulation tasks, such as extracting prey from crevices and burrows, opening bivalve shells, and arranging middens in front of den entrances. Octopuses use multiple suckers on a single surface for a power grasp that supports their locomotion or permits the animal to carry or move small objects. Similar to squids engaged in prey capture, octopuses can project an arm from their body, attach a group of distal suckers, and pull an object toward themselves by shortening the arm. I investigated octopuses' use of suckers in similar tasks under controlled, reproducible laboratory conditions. Because larger suckers can generate larger adhesion forces, I hypothesized that the larger suckers toward the base of the arm would be preferred in tasks requiring the arm to employ greater forces. Octopuses did not use the strategy found in squid tentacles: applying suckers of appropriate force generation to a surface and lifting or pulling the arm. Instead, in many cases they used a variety of arm movements in combination with different functional groups of suckers. In addition, different arms performed different roles. When animals were restricted to the use of a single arm, they preferred to use suckers in the middle positions of the arm to support this coordinated arm-sucker activity. Contrary to a view of suckers as passive agents reflexively reacting to surface contact, these results are consistent with the known neural organization of the octopus arm and also with complex sucker-arm coordination in the performance of manipulation tasks.

Mantle cavity pressures are frequently hypothesized to drive venous return in the high-output circulatory systems of coleoid cephalopods. However, studies using non-invasive, imaging ultrasound on resting cuttlefish (Sepia officinalis Linnaeus, 1758) conclude that mantle cavity pressures do not drive venous return. Interestingly, data from cuttlefish showing sustained mantle hyperinflation indicate instead that forces within the mantle's tissues could aid circulation. We hypothesize that alternating contractions of the radial and circular mantle muscles create a bellows-like effect on mantle capillaries. This effect could be propulsive during normal ventilation and jetting but could stop circulation when the cuttlefish is engaged in sustained mantle hyperinflation. Sustained mantle hyperinflation accompanies some behaviors, for example the Deimatic Display. The metabolic consequences of strangulated circulation might limit the duration of these behaviors.

We systematically analyzed octopus body patterns, based on locations of chromatophore nerve projection, using a proposed new species in the Octopus vulgaris Cuvier, 1797 complex, Octopus insularis Leite and Haimovici, 2008. Although some taxonomic studies have used body patterns as characters to describe octopus species, a systematic analysis would provide detailed descriptions to assist reliable comparisons among species. This approach also links body patterns, behaviors, and underlying physiology of the chromatophore system. Body patterns were characterized by percent occurrence, areas of skin, and number of components in each. To verify the distribution of chromatic components, skin patterns, and colors among areas of the body, we ran a cluster analysis on occurrence of the components. We identified a total of 16 chromatic, 5 texture, 9 skin units, 6 colors, and 9 chronic body patterns. The cluster analysis showed twelve distinct skin areas of the components' distribution (expressive fields). Smaller fields were found in areas with complex patterns, especially around the eyes, while larger ones were found in areas with simple patterns. These findings differentiate between morphological and physiological units of the display system. The strong degree of similarity among photographs also supports previous taxonomic studies that pointed to morphological similarity within this species from the oceanic islands of northeastern Brazil.

Despite high octopodid diversity in the deep sea, the few opportunities to observe these animals in situ limit tests of behavioral predictions made from anatomy. Over the last decade, I have made numerous opportunistic observations of these octopuses using submersibles and remotely operated vehicles. Most commonly seen were octopuses near hydrothermal vents in the North Pacific Ocean at greater than 2200 m depth. Despite the potential submersible-created artifact, the observed behaviors of octopuses of the genera Benthoctopus Grimpe, 1921, Graneledone Joubin, 1918, and Vulcanoctopus González et al., 1998 are reported here. Benthoctopus and Graneledone differ in wariness and in egg-brooding postures, although both genera produce large eggs from which male hatchlings emerge with clearly developed copulatory arms. In a behavior interpreted as foraging for infauna, octopuses of both genera move the mid-section of their arms through the upper sediment. Graneledone seems more common, perhaps because individuals are typically larger and move more slowly. The greater wariness of Benthoctopus increases the species' propensity to jet and limits observations and capture. Despite considerable submersible time spent in their habitat, octopuses of Vulcanoctopus remain little known; only male specimens are available for study. The few data available indicate that deep-sea octopuses take small prey, as Voss (1988) predicted based on the lack of the esophageal crop and the small posterior salivary glands. If deep-sea octopuses rely on small prey, the need for a crop to serve as a food storage organ is minimized, as is the need for glands that produce venom to subdue large and potentially dangerous prey.

The study of molluscan behavior offers intriguing possibilities and promising results, although focused mainly on coleoid cephalopods. Octopuses in particular have enduring individual differences in reactions that are strong enough to be called personalities (Mather and Anderson 1993). Given a floating or manipulable object, octopuses do not always habituate to its presence but may instead perform simple object play (Mather and Anderson 1999). One can argue they have basic concept formation, both in assessment of complex sensory information and choice of motor output. Sutherland's (1963) series of tests on octopus shape discrimination revealed that octopuses had no simple rules but were instead learning what to learn. Anderson and Mather (2007) found that octopuses chose one or more of three methods to penetrate clam shells. Each method used a different effector and prey orientation, all while the clam was under the arm web and thus visual information was unavailable. These different aspects of behavior all indicate cephalopods may have a simple ‘primary consciousness’ (Mather 2007), integrating perception and learned information with motivation to make decisions about complex actions. Such a conclusion offers new possible directions for the study of molluscs.

We collected six species of freshwater snails from Dominica, including Biomphalaria kuhniana (Clessin, 1883), Gundlachia radiata (Guilding, 1828), Helisoma (=Planorbella) trivolvis (Say, 1817), Melanoides tuberculata (Müller, 1774), Neritina punctulata Lamarck, 1816, and Physa marmorata Guilding, 1828. Our collections indicate that un-reported species such as G. radiata and H. trivolvis are established on Dominica, West Indies. We tested a limited number of M. tuberculata for rickettsial pathogens, Neorickettsia spp., but did not identify this agent. Three species of snails previously reported from Dominica, Biomphalaria glabrata (Say, 1818), Biomphalaria straminea (Dunker, 1848), and Thiara granifera (Lamarck, 1822), were not collected. Our data suggest that B. glabrata has not re-emerged as a prominent component of the freshwater snail fauna since it disappeared or was locally eradicated. In addition, previous reports of B. straminea were probably misidentifications of B. kuhniana, and some abnormally large specimens of M. tuberculata from Freshwater Lake could be misidentified as T. granifera. Our sampling was not adequate to demonstrate that T. granifera was absent from Dominica. We determined that B. kuhniana was not eradicated by previous molluscan control regimes. Additional studies on the relationships of freshwater snails in Dominica to helminths of animals and humans are needed to understand the public and veterinary health significance of these snails.

Octopuses function as important prey and predators in many continental-shelf marine ecosystems. Understanding activity cycles of octopuses should help define their mode of foraging and potential resource utilization and, therefore, their niche within the marine community. Unfortunately, little is known concerning activity cycles of octopuses, especially during their juvenile life-history stages. Here, I present observations on juvenile activity in Octopus bimaculoides Pickford and McConnaughey, 1949 over three observational weeks in a semi-natural laboratory setting. Octopuses on average were nocturnal, but some individuals were active during daylight hours in all three observational weeks. Nocturnal activity cycles may decrease the risk of predation on juveniles by visual fish predators hunting during daylight hours. However, inter-and intraspecific competition with other octopuses in different life history stages, including adult O. bimaculoides and adult and juvenile Octopus bimaculatus Verrill, 1883 is also likely during nighttime hours. Further studies are needed on the relative influence of predation and competition on octopus activity cycles and the resulting consequences for octopus populations.

Recent expeditions to the Atlantic sector of the Southern Ocean have yielded valuable collections of shelf and deep water polyplacophorans. These included several specimens of Stenosemus simplicissimus (Thiele, 1906), a species previously known only by its holotype and type locality at the Cape of Good Hope. The new material enabled a thorough morphological redescription of the species by studying valve, perinotum, and radula characters with SEM. The new records from Shag Rocks and the eastern Weddell Sea enlarge the species' biogeographic distribution from the temperate South African region to the polar South Georgia and Weddell Sea regions. Its bathymetric range is extended from 318 m to 285–1064 m. The limited occurrence of deep-water Antarctic polyplacophorans may be caused by benthic predators that limit the expansion of non-herbivorous chitons in the Antarctic deep sea.

Hexaplex trunculus (Linnaeus, 1758) is a gonochoric marine gastropod. Previous studies demonstrated that the biocide TBT (tributyltin) induced a sexual abnormality known as imposex (superimposition of male sexual characters onto females) in this whelk. Our study showed imposex in 19 stations out of 20 along the Tunisian coast. The frequency of imposex ranged from 0 to 100%. Among the 19 sites where the condition was found, 8 were considered as highly affected by imposex (VDSI > 3.7), 6 were moderately affected (VDSI > 1.3), and 4 were slightly affected (VDSI > 0). The most affected population was observed in the Bizerta Channel where the highest boating traffic was recorded; no imposex features were found in the Sea of Zarat where boating traffic was very low. Significant differences in imposex levels were obtained among sites with low, moderate, and high boating traffic. All the imposex indices values (I%, RPSI, RPLI, VDSI, FPL, and VDL) were significantly more elevated at sites with high boating traffic compared with sites with low and moderate boating traffic. Malformations of the penis were observed only in five stations and in very low rates, but where imposex rates were high. The incidence of penis malformation in males was significantly related to the boating traffic, I%, and VDSI. However, in females, a correlation was obtained only for the RPLI. The present study provides data on imposex level and penis malformations in H. trunculus from the Tunisian Coast that could be used as a starting point for future monitoring programs and for temporal trend surveillance related to TBT pollution in Tunisia where the use of TBT is not yet banned.

Water levels in the regulated Snake River, southern Idaho, U.S.A. can fluctuate daily and seasonally due to hydroelectric demands. The federally listed threatened Bliss Rapids snail, Taylorconcha serpenticola Hershler et al., 1994 (Family: Hydrobiidae), survives in and near these fluctuation zones. Remaining T. serpenticola populations occur only in sections of the Snake River that are impacted by these hydroelectric facilities and associated springs. Because effects of rapid draw-down in fluctuation zones on T. serpenticola are unknown, we conducted a laboratory experiment to evaluate potential impacts of desiccation. Our experiment compared desiccation resistance at several air temperatures, on dry and wetted substrates, and for ‘small’ vs. ‘large’ snails. Probit regression-maximum likelihood models estimated lethal time (LT₅₀) values. Survival was significantly greater on wetted substrate than on dry substrate and was lowest at temperatures <0°C and at 37°C on dry substrate. Survival was greatest at 17°C on wetted substrate. There was no significant difference in survival at temperatures above 0°C on dry substrate other than at 37°C. LT₅₀ survival ranged from 0.5 hours at −7°C to 157.0 hours at 17°C on wetted substrate. There were no significant differences in survival relative to snail size in any treatment. Our results suggest that desiccation could impact T. serpenticola populations if snails become stranded on dry substrates during rapid water-level fluctuations of the Snake River, particularly during subzero winter or extreme high summer temperatures. The most important factor determining survival would be the ability to find refuge on the undersides of cobbles, where snails typically occur, or in habitats that remained moist for the duration of the draw-down of the river.

Three yellow sandshell mussels, Lampsilis teres (Rafinesque, 1820), were observed in Lake Tuscaloosa, Alabama, and the temporal display pattern of their mantle-flap lures was investigated in situ. All three gravid females fully displayed their mantle-flap lures after dark during each nighttime visit (N = 3) but none displayed their lures during daytime (N = 3). An encounter between a mantle-lure and a largemouth bass was observed. These observations are the first reported of in situ mantle-flap lure displays and fish host encounters for L. teres, and support previous studies of diel display patterns in other mantle-lure displaying mussels. This diel lure display may be related to the ecology of the fish hosts they seek to attract. Future daytime and, especially, nighttime field observations of bivalve mussels with mantle-flap lures may greatly improve understanding of their reproductive ecology.

The estuaries and rivers of the western coast of Florida have been under intense study for some time to identify relationships between inflows, salinity, and natural resources. The molluscs have been shown to be especially sensitive to salinity in other parts of the world. The current study performed a meta-analysis of existing data sets of southwest Florida mollusc communities to identify salinity-mollusc relationships at regional scales. The mollusc species are controlled more by water rather than the sediment they live in or on. The most important variable correlated with mollusc communities was salinity, which is a proxy for freshwater inflow. Although total mollusc abundance was not a good indicator of inflow effects, certain indicator species characterized salinity zones in southwest Florida rivers. Corbicula fluminea (Müller, 1774), Rangia cuneata (Sowerby, 1831), and Neritina usnea (Roding, 1798) were the only common species that occurred in the oligohaline zone at salinities below 1 psu. Although C. fluminea was the best indicator of freshwater habitat, it is a non-native, invasive bivalve species. The bivalve R. cuneata is an indicator of mesohaline salinity zones with an estimated tolerance of up to 20 psu. The gastropod N. usnea is also common in fresh to brackish-water salinities. Polymesoda caroliniana (Bosc, 1801) was present at salinities between 1 and 20 psu, which span the oligohaline and mesohaline zones. Tagelus plebeius (Lightfoot, 1786), Crassostrea virginica (Gmelin, 1791), Mulinia lateralis (Say, 1822), Littoraria irrorata (Say, 1822), and Ischadium recurvum (Rafinesque, 1820) are also good indicators for polyhaline salinity zones. These salinity ranges can be used to predict changes in mollusc assemblages in response to alterations in salinity that result from actual or simulated changes in freshwater inflow.

Individuals of Achatina fulica (Bowdich, 1822) were observed preying on veronicellid slugs at two sites on the island of Oahu, Hawaii. As such, the presence of A. fulica may pose a greater threat to terrestrial mollusc conservation than previously imagined. It is our hope that this note provides some impetus for other researchers to explore the possible predation impacts of introduced populations of A. fulica and to consider the possibility that other introduced snails and slugs may be having as yet unforeseen or unnoticed impacts.

We documented the period of gravidity, identified the fish host, and described the glochidia for two mussel species, Fusconaia burkei (Wright, 1898) and Pleurobema strodeanum Walker, 1922, in Eightmile Creek, Walton County, Florida. Populations of both species were checked monthly from December 2003 to October 2004 and were found to be gravid from the middle of March to late May. The size and shape of F. burkei and P. strodeanum glochidia were similar. Conglutinates released by F. burkei were pink-colored and cylindrical in shape, tapering sharply on both ends. Pleurobema strodeanum conglutinates were creamy or peach-colored and wider with a more flattened appearance than those of F. burkei. Ten potential host fish species were exposed to either F. burkei or P. strodeanum glochidia. We identified the blacktail shiner (Cyprinella venusta) as a host fish species for both F. burkei and P. strodeanum.