Gastropoda

Some species of hermit crabs can locate chemically predation sites where snails are consumed and subsequently obtain their shells. This study addressed four questions: (1) Is chemotaxis to snail odors prevalent among hermit crabs? (2) Do members of hermit crab lineages respond similarly to common snail odors? (3) Do hermit crabs respond more acutely to snails whose shells they most frequently occupy? and (4) Does phylogeny of snails influence responses by hermit crabs? Two sets of congeners (Clibanarius vittatuslC. tricolor and Dardanus venosuslD. fucosus) in the family Diogenidae, and three congeners (Pagurus pollicaris, P. longicarpus, and P. annulipes) in the family Paguridae were tested. Fifteen species of snails from 11 families served as test odors. Hermit crab response was measured by the fondling display, where one hermit crab investigates the shell of a neighboring crab. The diogenids discriminated odors more readily than did the pagurids. Correlations between responses and shells most frequently occupied existed for C. vittatus and D. venosus. Clibanarius tricolor was the only crab to respond to confamilial test odors.

Distributional patterns of the pulmonate limpet, Siphonaria
pectinata, were studied at an intertidal rock outcrop near
Boca Raton, Florida from August to November 1982. The
locations of all limpets (167,368) in a 272m2 region of
the outcrop were analyzed statistically including the use of
computer-aided trend surface analysis. Limpet distribution
was restricted seawardly by algal mats near mean sea level
(MSL) and by the lack of tidal wetting at approximately 2.0
ft above MSL. The highest concentrations of ~. pectinata
occurred from 0-1.5 ft elevation, on the seaward side of the
outcrop.
gregarious
clumping.
The distribution was highly clumped, with
homesite selection contributing to local
Limpet homing experiments were performed on
isolated rocks in the Boca Raton Inlet. Siphonaria
pectinata is capable of homing by means of topographic
memory systems alone. External cues, chemical cues and/or
dead-reckoning systems are not required for homing but may
contribute to a hierarchy of homing stimuli.

Healing of wounds in the foot of Siphonaria petinata (Linne) was compared with healing vertebrates and in other molluscs. Wounds were two mm long and one mm deep. Animals were maintained in the laboratory in artificial sea water at 25C and were observed and sectioned at intervals for 28 days. Within one day, the wound filled with fluids, leucocytes and debris. Within two days, leucocytes formed a cot against the damaged muscle tissues. By the eighth day, some repair tissue had formed and epithelium covered most of the wound surface. Epithelium and supporting tissues regenerated within 18 days. Muscle and granulated cells had partially regenerated within 28 days. Healing of wounds in S. pectinata is more similar to healing in prosobranch molluscs than to healing in bihalves or in vertebrates.