WARNING: article contains graphic images
As his teenage son recovers in hospital after apparently being bitten by sea lice, a Melbourne father has filmed flesh-eating critters he caught at the same beach going crazy for raw steak.
Sam Kanizay emerged from a dip at Brighton Beach on Saturday night with legs covered in blood seeping from dozens of tiny wounds on his calves and feet.
Desperate for answers, his father Jarrod Kanizay returned to the beach on Sunday night armed with a pool net, wetsuit and pieces of steak.
The result is a stomach-churning video showing dozens of sea lice devouring Mr Kanizay's bait.
"We found thousands of little mite-type creatures in our net.
"We put them in an Esky and brought them home and looked at them intently and let them swim in white dishes with red meat," Mr Kanizay said.
"Interestingly, overnight they've essentially all clung to the meat and has been busy overnight eating it."
Sixteen-year-old Sam continues his recovery at Dandenong Hospital after doctors struggled for most of Sunday to control the bleeding.
Mr Kanizay said staff at both Dandenong Hospital and Sandringham Hospital, where Sam was first taken, were stumped by the case.
"They took a biopsy yesterday to make sure there are no critters living inside.
"One would assume no and that he's going to be fine but we're taking every precaution."
"Both at Sandringham Hospital and also Dandenong Hospital, no one had seen anything like this before and they're all pretty fascinated by it."
While sea lice are suspected of being the creatures who bit Sam's legs, it's still unclear who is responsible for investigating the matter.
The Environment Protection Authority only do water monitoring in summer and will only become involved if the issue is polution-related.
The Department of Environment, Land, Water and Planning told Fairfax Media they couldn't become involved as the cause was yet to be identified.
Mr Kanizay said Sam was "in good spirits" and said he hoped a marine expert would come forward in coming day to establish which sort of creature ate his son's legs so it "doesn't happen to anyone else".
"We're a really positive family and we expect a full recovery."
University of Melbourne marine biologist Professor Michael Keough said sea lice were a possibility.
"They're scavengers who'll clean up dead fish and feed on living tissue," Professor Keough said.
"They're mostly less than a centimetre long, and so the bites they make are pretty small, and so that's more consistent with pinprick size marks."
"It's just food for them. Especially if he's been standing around for a long time, it's the chance for more of them to come in and start biting.
"[They will] just be attracted to a little bit of blood. And if he's standing in the water and he's cold [he] may not notice a whole lot of little bites."
- with Carolyn Webb