Innate behaviours are responses to specific stimuli due to the activation of developmentally encoded neural pathways. In marine environments, fishes exhibit innate predator recognition via detecting and interpreting chemical cues. Innate predator recognition is critical for optimal predator avoidance during early life history stages, when organisms are particularly vulnerable. Additionally, an ability to rapidly differentiate between non-predatory and predatory animals is crucial because it avoids wasting energy and time on futile anti-predator behaviours.
Although studies have investigated innate responses of larval fish to predators, no studies have examined innate predator recognition in egg-laying elasmobranchs (sharks, skates and rays). As a result, it is unknown how encountering and interpreting chemical cues, produced by predators, will impact the embryonic development of elasmobranchs. The purpose of this study is to determine if Port Jackson sharks (Heterodontus portusjacksoni) exhibit innate predator recognition during embryonic development and how this may impact their development.
Viable Port Jackson shark eggs will be collected from Jervis Bay, NSW and used for laboratory-based chemosensory experiments. These involve introducing predator and herbivorous fish odours, as well as conspecific alarm cues to embryos and observing their responses. Heart rate will be measured before and after the introduction of chemical cues, by using ventilatory rates as a proxy for heart rate. An understanding of how predation pressure impacts embryonic development in egg-laying elasmobranchs may help to design conservation strategies that better protect H. portusjacksoni, and other species during early life history stages.