Innate response based on visual cues of sympatric and allopatric predators in Nile tilapia.

Predators are an important selective pressure for prey, and responses to visual exposure to non-predators and to allopatric and sympatric predators may assist the understanding of how prey animals recognize and distinguish potential threats. Here, we visually exposed predator-naïve Nile tilapia (Oreochromis niloticus) to aquaria with only water (handling-negative control), a non-predator fish (Cyprinus carpio), a South American catfish (Pseudoplatystoma coruscans, allopatric predator), and an African catfish (Clarias gariepinus; sympatric predator). We found that Nile tilapia displayed antipredator responses to both predator catfish but not to non-predator fish or negative control conditions.

Ventilation responses to predator odors and conspecific chemical alarm cues in the frillfin goby.

The chemical detection of predation risk is direct when based on predator odors, or indirect when an injured conspecific or heterospecific signal it. Physiological adjustments may be necessary in parallel to defensive reactions to cope with an imminent risk. Here, we tested the effects of predator odors and conspecific chemical alarm cues in ventilation response (VR) of frillfin goby, Bathygobius soporator, because this response increases oxygen uptake for supporting behavioral tasks.