ABSTRACT: For many animals, foraging is a complex activity involving decisions of when, where, and how to feed, as well as what to feed upon. Flexibility in foraging (i.e. switches among activities, habitats, or food items) is presumed to contribute to overall fitness, and is an important component of theoretical models of animal feeding behavior. The importance of switching among feeding methods is less well described, but may be very important for marine sediment dwellers (infauna). For example, many infauna switch between suspension and surface-deposit feeding depending on water flow. However, infauna often lose feeding appendages to browsing predators, and the ability to switch to alternative feeding methods which are not dependent on those appendages should be advantageous after such tissue losses. Laboratory experiments examined the effect of feeding appendage loss on 2 species of spionid polychaetes which have different alternative feeding modes when intact. Behavior of individual worms with 0, 1 or 2 palps removed was videotaped for 2 h within 3 to 4 d of palp removal. Loss of both feeding palps induced switches to alternative feeding modes involving mouth-feeding: Rhynchospioglutaeus fed on the surface, Pseudopolydorakempijaponica fed below the surface. As measured by time spent feeding and by fecal production, the alternative was effective for R.glutaeus but not for P.k. japonica. The results emphasize the potential importance of injury and subsequent switching as factors determining feeding behavior.

KEY WORDS: Browsing . Foraging behavior . Infauna . Polychaete . Predation risk . Spionid . Surface-deposit feeding . Sublethal predation

Published in MEPS Vol. 125 (1995) on September 14
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1995