News Archive

Marine neurobiology PhD student Ryan Kempster claimed the runner-up prize in UWA's inaugural Three Minute Thesis Competition on July 15.

After scraping through the first round with an admittedly unscripted talk, Ryan went on to impress the judges in the final with his thesis titled:

‘The role of electroreception in the feeding behaviour of sharks.'

Electroreception could be described as a shark's seventh sense. In addition to the five senses shared by most vertebrates, sharks use their ‘lateral line system' to detect vibrations travelling through the water.

They also have a special knack for sensing electrical signals emitted by predators and prey; in fact they may be more sensitive to electric fields than any other animal.

How do they do it? With a network of jelly-filled canals called the ‘ampullae of Lorenzini', visible externally as small pores on their heads (see photo).

Different shark species have different electrical sensitivities and pore patterns, which can often indicate feeding behaviour.

Ryan explains: "Bottom-dwelling species that feed on mussles, shellfish and other organisms hiding beneath the substrate have dense aggregations of pores around the mouth, that help guide them to the final attack... You can learn so much just from the pores themselves."

Understanding electroreception and its role in feeding behaviour has implications for the fishing and diving industry. ‘Shark shields' and similar devices are designed to repel sharks by emitting a constant electric charge. They can be worn by divers and surfers, and could potentially be used on long lines and trawling nets to prevent unintentional shark catches.

"The problem is that there's not much scientific backing to the use of these machines," says Ryan. So far they have been tested only on a few species like the great white and tiger shark; little is known about how sharks with different sensitivities and pore patterns will react.

"We want to study as big a range of species as possible, look at their electrical sensitivity, and then start to infer whether devices like that are actually appropriate.

"It all comes together - when we know about the pore patterns, it tells us a lot about their feeding behaviour, and when we know about the sensitivity, we can develop better devices."

So how will Ryan spend his runner-up prize of a $1000 research or travel grant? With a new remote-controlled camera that will allow him to observe sharks in the lab from a distance, without affecting their natural feeding behaviour.

To find out more, visit Ryan's website at www.supportoursharks.com or search ‘support our sharks' on Facebook.

Page 6: The UWA Oceans Institute December Newsletter

Media references

Maryann Evetts (The UWA Oceans Institute), (+61 8) 6488 8116