Scientists in Australia were surprised to find Port Jackson and crested horn sharks munching on the urchins.
Researchers studying lobster predation on sea urchins were surprised to record footage of an unexpected urchin predator: sharks.
After setting up a camera in a lobster den overnight – with “strategically placed” urchins inside the den – they were shocked when most of the urchins were eaten by Port Jackson and crested horn sharks.
“This was designed to be a lobster experiment, but sharks came in and ate the majority (45%) of the tethered urchins while lobsters ate few (4%),” says Jeremy Day, a PhD student at University of Newcastle who led the study.
“Lobsters seemed generally uninterested in eating urchins,” he says.
The footage shows the sharks sneaking in to snack on huge sea urchins, which they can handle with ease.
“It has been thought until now that there were few or no predators capable of handling very large urchins,” says Day. “Sharks are overlooked predators of sea urchins in New South Wales.”
This discovery challenges previous beliefs that lobsters are key predators of sea urchins and could help conservationists protect reefs by controlling urchin numbers.
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