Abstract
Sharks use highly sensitive electroreceptors to detect the electric fields emitted by potential prey. However, it is not known whether prey animals are able to modulate their own bioelectrical signals to reduce predation risk. Here, we show that some shark (Chiloscyllium punctatum) embryos can detect predator-mimicking electric fields and respond by ceasing their respiratory gill movements. Despite being confined to the small space within the egg case, where they are vulnerable to predators, embryonic sharks are able to recognise dangerous stimuli and react with an innate avoidance response. Knowledge of such behaviours, may inform the development of effective shark repellents.
Highlights
Electroreception is found throughout the animal kingdom from invertebrates to mammals and has been shown to play an important role in detecting and locating prey [1,2], mates [3], potential predators [4,5] and is thought to be important in orienting to the earth’s magnetic field for navigation [6,7,8]
During early embryonic development [11,14], bamboo sharks are sealed within a pigmented egg case, where their presence would be masked to any visually-driven predators and there would be no exchange of fluids [11] with the surrounding seawater, negating their detection via either mechanoreceptive or olfactory signals
Embryos as young as stage 32 would only respond if the electric field was of sufficient strength, approximately $0.9 mV/cm (Fig. 3B)
Summary
Electroreception is found throughout the animal kingdom from invertebrates to mammals and has been shown to play an important role in detecting and locating prey [1,2], mates [3], potential predators [4,5] and is thought to be important in orienting to the earth’s magnetic field for navigation [6,7,8]. During early embryonic development (stages 3–25) [11,14], bamboo sharks are sealed within a pigmented egg case, where their presence would be masked to any visually-driven predators and there would be no exchange of fluids [11] with the surrounding seawater, negating their detection via either mechanoreceptive (lateral line) or olfactory signals.
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