It’s safe to go back in the water, says marine biologist who identified the miniature attackers as lysianassid amphipods

This article is more than 3 years old

This article is more than 3 years old

The “meat-loving” marine creature that ate at the legs of a Melbourne teenager has been identified as a flesh-eating sea flea, known as a lysianassid amphipod.

Marine biologist Dr Genefor Walker-Smith said the creatures, which left 16-year-old Sam Kanizay with significant bleeding from his legs, were a small, scavenging crustacean that usually fed on dead fish or sea birds.

Kanizay said on Monday he was soaking his legs at Brighton beach when he felt the creatures attack, causing wounds that would not stop bleeding.

Facebook Twitter Pinterest Sam Kanizay’s legs after sustaining bites from the lysianassid amphipod. Photograph: Jarrod Kanizay/PA

But Walker-Smith told the ABC’s RN Breakfast program the amphipods posed no risk to the public and that it was safe to go back into the water. She said amphipod bites were common and “normally you would feel them or brush them off”.

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It was a combination of cold water numbing Kanizay’s legs, bad luck, and standing still that led to an exceptional number of bites.



“Sam may have walked past a group that was feeding on something. He might have bumped a dead crab and stirred them up,” she said.

“He was standing still for a long time in the water and the water was cold, I don’t think he actually felt them biting. The fact that he just stood there gave them plenty of time to latch on.



“They don’t normally attack humans, it’s just an unfortunate coincidence.”

Amphipods are related to shrimp and prawns but are smaller in size, ranging from 6-13mm. They are not venomous and their bites do not cause any lasting damage.

They are commonly known as sea fleas or sea lice, although Walker-Smith noted that sea lice was more commonly used to refer to isopods, a different type of crustacean.

On Monday, footage taken by Sam’s father Jarrod Kanizay showed a sample of the amphipods swarming around pieces of steak.



“These guys clearly love red meat, they are devouring this,” he said.

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Sam Kanizay told reporters that he initially thought the amphipods were sand on his legs and brushed the creatures off.

“By the time walked across the sand about 20 metres … I looked down and noticed that I had blood all over my ankles and feet,” he said.

Walker-Smith, who examined samples of the amphipods obtained by the family, said they were a natural part of the marine ecosystem that performed a vital role in the food web.



“If we didn’t have them, we’d have a sea full of dead fish and dead birds,” she said. “It’s just part of the food web, the chain of life.”