Meeting Abstract

P2.80  Jan. 5  Observations on the feeding behavior of Lewis� moon snail, Euspira lewisii (Gould, 1847) NEWEL, M.S.; BOURNE, G.B.*; MCGAW, I.J.; University of Calgary and the Bamfield Marine Sciences Centre; University of Calgary and the Bamfield Marine Sciences Centre; University of Nevada, Las Vegas and the Bamfield Marine Sciences Centre bourne@ucalgary.ca

Lewis� moon snail, Euspira lewisii, is an important predator of infaunal bivalve molluscs. This large naticid gastropod is found commonly burrowing in sand and mudflats along the Pacific Coast of North America. Euspira, collected in Barkley Sound, British Columbia, were taken into the laboratory where we investigated feeding behavior by direct observation, radiography and morphometric analyses of their prey. Like most Naticidae, Euspira individuals capture bivalves with muscular propodia and mesopodia, and subsequently completely envelop their prey in mucus. Euspira usually bore through bivalves� shells, typically immediately ventral to the umbo, using a combination of radular scraping and corrosive glandular secretions from an accessory boring organ located at the tip of the extensible proboscis. When complete drill holes were produced, we suspect that snails fed entirely through those holes. However, contrary to most literature reports of extant and fossil naticid-drilled bivalves, we found that successful predation occurred even with incompletely drilled or no drill holes in the bivalve shell. Through some unknown mechanism, they seemed capable of causing their ensnared prey to gape, at which point Euspira did not start the laborious drilling process or simply abandoned it. Instead, Euspira fed through the ventral gape via a hole in the mucus envelope. Understanding the mechanisms and behavioral patterns involved in prey capture and subsequent feeding by naticid gastropods may lead to a better appreciation of their role as major predators in both fossilized and extant marine environments.