CHEMICALLY MEDIATED ESCAPE BEHAVIOR IN THE MARSH PERIWINKLE LITTORARIA-IRRORATA SAY

Marsh periwinkles Littoraria irrorata Say substantially reduce their exposure to predatory crown conchs Melongena corona Gmelin by ascending intertidal plants during high tide, when conchs actively-hunt. Studies were conducted to determine if the periwinkle's responses to predator contact were comparable to those of gastropods lacking an equivalent strategy of predator avoidance. Marsh periwinkles exhibit an escape response to contact with crown conchs, consisting of a 64% increase in average speed of locomotion, and a 68% increase in average rate of cephalic tentacle contacts with the substratum. Crown conch mucus alone is sufficient to elicit a full-strength response. The cephalic tentacles, anterior foot, and posterior foot of marsh periwinkles appear equally sensitive to this predator's mucus, but periwinkles do not move in any particular direction relative to the site of stimulation. Mucus of nonpredators (ragged sea hares, scallops) did not elicit a significant escape response in marsh periwinkles. Contact with mucus from each of five predatory neogastropods did elicit a significant response, but contact with the natural predator (M. corona) elicited a significantly stronger response than the others. The marsh periwinkle's escape response and chemo-discrimination ability is similar to that reported for some other gastropods.