The Effect of Palp Loss on Feeding Behavior of Two Spionid Polychaetes: Changes in Exposure

The effects of sublethal predation on foraging behavior are potentially important. Such predation changes both the condition of the individual and the cost or risk associated with further predation. Tissue loss to predators is a very common phenomenon in marine sedimentary environments; often the tissue lost is the organism's feeding structure. We asked how the loss of feeding structures would affect the foraging behavior of two species of spionid polychaetes, and whether the responses to palp loss are predictable. Rhyncospio glutaeus and Pseudopolydora kempi japonica represent the ends of a spectrum of risk associated with tissue exposure during feeding. In both species, the loss of one or both palps significantly increased the amount of tissue exposed, and the frequency of exposure, but not the duration of each exposure. All changes were consistent with the normal foraging behaviors of these species. Estimates of relative energy gain suggest that these responses may partially mitigate the effect of palp loss, although potentially increasing the risk of predation.