The worm re-turns: hiding behavior of a tube-dwelling marine polychaete, Serpula vermicularis

The polychaete worm Serpula vermicularis (Serpulidae) filterfeeds at the mouth of its calcareous tube, but retreats intothe tube when startled by mechanical stimuli likely to be associatedwith predators. While in its tube, a worm is safe but cannotfeed. Thus, hiding has a lost-opportunity cost. We show thatthis cost can be substantial, given that food in the naturalhabitat appears in pulses, and good feeding conditions may notlast long or recur frequently. We expect that a worm's hidingtime will be sensitive to the lost-opportunity cost, and wepresent data from a series of experiments that support thisprediction. The worms seem able to track relatively short-termchanges in food availability, and some evidence suggests thatthey assess food availability on a relative basis, comparingcurrent feeding conditions to those recently experienced. Hidingand other types of cryptic behavior are common antipredatortactics, and animals may commonly adjust the durations of suchbehaviors to current benefits and costs (including lost opportunity),as they perceive them