Learning about danger by young hellbenders (Cryptobranchus alleganiensis): are antipredator strategies ontogenetically plastic?

Abstract

Some aquatic species are able to learn to recognize chemical cues from predators through classical conditioning. In previous tests, laboratory-reared larval hellbenders (Cryptobranchus alleganiensis) showed weak antipredator responses to introduced predators (trout) compared to responses to their native predators, such as bass and sculpin. However, hellbender larvae that were conditioned with conspecific alarm cues at six months of age learned to recognize trout odour, but the responses of younger larvae to alarm cues have not been tested and the ontogeny of learning abilities is not known. In this study, we successfully trained younger larval hellbenders (4 months old) to recognize trout. Moreover, we found that the learned responses of younger hellbenders (decreased activity) are different from those of the older hellbenders (increased activity) in the previous study. This ontogenetic shift in behaviour may result from larvae increasing locomotor and sensory abilities and becoming more visible during the 4-6 month time period.