Comparable cross-taxa risk perception by means of chemical cues in marine and freshwater crustaceans

Abstract

Rapid identification of predation risk and modification of subsequent behaviour is essential for prey survival. In low-visibility aquatic environments, chemical cues emitted by hetero- and conspecific organisms may be an important information source if they identify risk or alternatively, indicate safety or resource availability. This study tested whether ecologically similar shrimp from disparate habitats have a comparable ability to identify predators from a range of taxa based on chemical cues. Shrimp from both temperate marine (Palaemon affinis) and tropical freshwater habitats (Caridina typus) exhibited similar behavioural responses, avoiding chemical cues from predatory heterospecifics, showing no response to non-predatory heterospecific cues, and preferring conspecific cues. These chemical cues also affected habitat selection, with structurally complex microhabitats favoured in the presence of predator cues but avoided in the presence of conspecific cues. The ability to differentiate predators from non-predators irrespective of taxa suggests identification might be due to the predator’s diet. An ability to alter behaviour based on vision-independent perception of ambient risk is likely to reduce capture risk while allowing individuals to maximise time spent on essential processes such as foraging.