ABSTRACT: The escape responses of many animals are finely adjusted to the risks of predation encountered in nature. Adult whelks Buccinum undatum from a population sympatric with the predatory asteroid Leptasterias polaris more readily exhibited violent leaping escape maneuvers (foot contortions), produced larger quantities of mucus, and more efficiently escaped predator attacks than adult whelks from a population allopatric with the asteroid. However, newly emerged whelks (recruits) from both populations did not resort to strong escape maneuvers to flee L. polaris, but they nevertheless increased their crawling activity. The behavioral response of recruits appears to be predator-specific in the sympatric population, but not in the allopatric population. In the sympatric population, the tendency of whelks to exhibit foot contortions under predation risk increased with size. Our results suggest that where whelks coexist with L. polaris the capacity to recognize this predator as a threat is innate, and elaborate antipredator behaviors develop during ontogeny. We hypothesize that the greater responsiveness of large individuals is adaptive as it enables them to take advantage of the feeding opportunities that arise from close associations with L. polaris.

KEY WORDS: Gastropod · Buccinumundatum · Defensive responses · Predation risk · Sympatry · Allopatry · Ontogeny

Published in MEPS Vol. 142 (1996) on October 24
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1996