INTER-POPULATION AND INTRA-POPULATION VARIATIONS IN THE RESPONSE OF THE WHELK BUCCINUM-UNDATUM TO THE PREDATORY ASTEROID LEPTASTERIAS POLARIS

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 polar is more readily exhibited violent leaping escape maneuvers (foot conto rtions), produced larger quantities of mucus, and more efficiently esc aped predator attacks than adult whelks from a population allopatric w ith the asteroid. However, newly emerged whelks (recruits) from both p opulations did not resort to strong escape maneuvers to flee L. polari s, but they nevertheless increased their crawling activity. The behavi oral response of recruits appears to be predator-specific in the sympa tric population, but not in the allopatric population. In the sympatri c population, the tendency of whelks to exhibit foot contortions under predation risk increased with size. Our results suggest that where wh elks coexist with L. polaris the capacity to recognize this predator a s a threat is innate, and elaborate antipredator behaviors develop dur ing ontogeny. We hypothesize that the greater responsiveness of large individuals is adaptive as it enables them to take advantage of the fe eding opportunities that arise from close associations with L, polaris .