Sea lice to blame for leaving teenagers legs a bloody mess

A Melbourne teenager who had his lower legs and feet badly attacked by sea lice is almost ready to leave hospital.

Sam Kanizay, 16, still has a few soft spots where the sea lice ripped into his flesh when he went for a dip at Brighton's Dendy Street Beach on Saturday night to cool his aching muscles following a tough game of footy.

He walked out with "hundreds of little pin holes" that wouldn't stop bleeding on his feet and ankles thanks to tiny scavengers who feed on flesh.

"They were so small but they've made such an impact on Sam. There must have been thousands around his legs," his father Jarrod Kanizay said.

Doctors were initially stumped about what had caused the excessive bleeding, but Jarrod Kanizay said the medics now know what they're dealing with.

"It's not a burrowing animal, it's not a toxic animal, and it just loves eating our flesh," he said.

His son was set to leave Dandenong Hospital.

Museums Victoria marine biologist Genefor Walker-Smith examined some of the creatures who bit Sam and found they were a scavenging crustacean known as lysianassid amphipods.

She said it was possible the bugs contained an anti-coagulant similar to that produced by leeches, which explained the inability to stem the flow of blood.

The family has now heard of four other cases of people who walked out of the water with unexplained bloody bites, but Kanizay said it wouldn't deter them from going for a dip.

"We all need to go into the water and celebrate the bay and use it," he said.

"Sam will be back in the water within no time, he can't wait."