Predator-prey interactions between decapod crustaceans and polynoid polychaetes
Trevor J. Rivers
Trevor J. Rivers
Predator-prey studies can lead to a better understanding of why animals evolved specific traits, and help us better comprehend how the ecological community functions as a whole. Numerous studies report that the size of both predator and prey strongly influence predation success; predators may shift prey preference with size, while prey may reach a size refuge. We examined the correlation between predator and prey size to survival of two intertidal scale worms. A luminescent species, Harmothoe imbricata, is often found on the same rock as a nonluminescent species, Lepidonotus squamatus. The decapod crustaceans Carcinus maenus, Cancer irroratus, Hemigrapsus sanguineus, andHomerus americanus were collected from the same habitat areas, and transported to separate flow-through tanks. All were regulated on a 12-hour light cycle so that it was dark during normal daylight hours. One worm and one crustacean were placed in a 10-cm square tank separated by a divider in darkness. After 10 minutes, the divider was removed and their interaction was filmed via low-light cameras with an infra-red (IR) light source. Luminescence was recorded via both by a night vision device and a photomultiplier. Three of the four predators consistently attacked the worms, with H. sanguineus only attacking a worm once. The two species of worms showed drastically different behavior when pursued by a predator. Prior to an attack, H. imbricata often swam quickly away, on occasion flashing if threatened. Under attack, they almost always luminesced while trying to escape via scale loss or autotomization. In contrast, L. squamatus latched on to the bottom of the tank without moving, dropping scales, or autotomizing. To date, it appears that all sizes of both worm species have more success evading smaller predators. Thus, predator size may have a stronger influence on survivability than prey size.
Perreault, Tamara R. and Rivers, Trevor J., "Predator-prey interactions between decapod crustaceans and polynoid polychaetes" (2012). Marine Lab Student Papers and Projects. Paper 8.