BENEFITS OF A PREDATOR-INDUCED MORPHOLOGY IN CRUCIAN CARP

Crucian carp (Carassius carassius) develop a deeper body in response t o chemical cues from piscivores. This change in body morphology has be en suggested to be a predator-induced defence. Here we investigate the possible benefits of the induced body morphology in laboratory experi ments. Pike foraging behaviour when feeding on crucian carp of differe nt body depths was recorded using video. Further, in a preference expe riment pike were allowed to choose between shallow-bodied and deep-bod ied crucian carp of similar lengths. Crucian carp body morphology did not affect predatory behaviours (activity, searching, following, obser ving, capture success) in northern pike, but an increase in crucian ca rp body depth led to an increase in handling time in pike. In the pref erence experiment, pike preferred shallow-bodied crucian carp over dee p-bodied. Thus, a change in body morphology, induced by the presence o f piscivores, benefits crucian carp by increasing piscivore handling t imes and an avoidance of the deep-bodied phenotype.