Damsel in distress: captured damselfish prey emit chemical cues that attract secondary predators and improve escape chances (#148)
In aquatic environments many prey animals possess specialised epidermal cells that when damaged elicit antipredator behaviours in responsive kin. Despite considerable study, the evolution of damage released alarm cues remains unclear. In an attempt to investigate one of the more promising hypotheses concerning the evolution of alarm cues, we examined whether the cue functions in a fashion analogous to the distress vocalisations emitted by many terrestrial animals. Our results suggest that chemical alarm cues in damselfish (Pomacentridae) may have evolved to benefit the cue sender by attracting secondary predators that disrupt the predation event, allowing the prey a greater chance to escape. The coral reef piscivore, Pseudochromis fuscus, chemically eavesdrops on predation events and uses damselfish alarm cues in an attempt to find and steal prey from primary predators. Field studies showed that P. fuscus aggregate at sites where prey alarm cue has been experimentally released. Furthermore, secondary predators attempting to steal captured prey of primary predators in a laboratory setting enhanced prey escape chances by 35-40%. The results are the first to demonstrate a mechanism by which reef fish may benefit from the production and release of alarm cues and highlight the complex and important role that semiochemicals play in marine predator-prey interactions.