Baby sharks play dead
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Shark pups sense predators' electric fields and react to them by essentially playing dead. The sharks will hold their breath and curl their tail around their body, which helps them to temporarily shut down their own electric field. The results of this research are promising, as they could be used to develop an effective shark repellent.
Image: louhan/iStockphoto

A recent discovery about shark behavior by marine scientists at The University of Western Australia's Oceans Institute may help researchers to develop an effective shark repellent.  

The study published in the open access journal PLOS ONE looked at the reaction of sharks while still developing in their egg cases. It found embryonic sharks can sense danger and avoid being detected by predators by staying still.

Lead author marine neuroecologist Ryan Kempster said young sharks can sense predators' electric fields and respond by reducing movement.

"Despite being confined to a very small space within an egg case where they are vulnerable to predators, embryonic sharks are able to recognise dangerous stimuli and react with an innate avoidance response," he said.  "This knowledge may help us to develop effective shark repellents."

Adult sharks are known to use highly sensitive receptors to detect electric fields emitted by potential prey. In the latest study, researchers found that embryos of some shark species employ similar means to detect potential predators and escape being eaten.

The researchers found that even within their egg cases, brown-banded bamboo shark embryos can sense electric fields that mimic a predator and respond by reducing respiratory gill movements to avoid detection.

A three-minute film by Ryan Kempster which illustrates the research, Survival of the Stillest: Bamboo Sharks, was selected to be screened last year at the prestigious US film festival, the Beneath the Waves Film Festival.

Editor's Note: Original news release can be found here.