Chemical alarm signalling in the polychaete Nereis (Neanthes) virens (Sars) (Annelida: Polychaeta)

Many aquatic organisms use chemical signals as a method of detecting the presence of a predator, but it is not known whether annelids do so. Nereis (Neanthes) virens is a common intertidal marine polychaete that is vulnerable to predation from aquatic predators, such as crustacean and fish species, when it partially leaves its burrow. We investigated whether chemical cues associated with predation affect the feeding activity of this polychaete. Exposure of N. virens to conspecific whole-body extracts significantly reduced out-of-burrow activity and the number of individuals feeding in comparison to a sea water control. The addition of whole-body extracts of the congener N. diversicolor, both sexes of the sympatric Arenicola marina and muscle extract of the flatfish predator Pleuronectes platessa (plaice) did not significantly reduce activity levels. The fish muscle extract, however, did significantly reduce the number of individuals feeding. The pattern of activity and timing of feeding through the scotophase was not altered in the presence of extracts, although feeding did occur during the photophase.