Still in shock: Sam Kanizay's wounds were seeping blood at Dandenong Hospital on Sunday, 18 hours after he emerged from the bay at Brighton with bloody legs, possibly by tiny bay creatures. Credit:Scott McNaughton The 16-year-old, who was sore from playing football, was soaking waist-deep in the bay about 6.20pm on Saturday. His legs felt a little numb, with a tingling sensation, but he assumed it was from the soreness and cold. "I wasn't really thinking about being eaten." Emerging from the water 30 minutes later, he saw under a street light that his legs were covered in blood from the calves down. "My first instinct was that I must have stepped on a rock," he said. "But I realised that couldn't have been it, because it was evenly distributed over my whole ankle and foot."

Teenager Sam Kanizay's bloody legs after possibly being bitten by something while bathing at Brighton. Credit:Jarrod Kanizay He walked across the esplanade, "leaving a path of blood", to his home nearby. His father, Jarrod, and sister, Gabby, 14, tried to wash the blood off in the shower. They couldn't staunch the flow, which seeped from pinprick-sized holes, so Jarrod drove Sam to Sandringham Hospital emergency department. Still bleeding: Sam Kanizay's wounds were still seeping blood on Sunday afternoon while doctors tried to work out what happened to his legs in the bay on Saturday night. Credit:Scott McNaughton Sam was given painkillers and antibiotics and had blood tests.

Jarrod then drove him to Dandenong Hospital in the early hours of Sunday for further tests. Enlarged photo of a sea louse Natatolana woodjonesi, (actual size about 25mm) - one of the species that inhabits Port Phillip Bay. Credit:Museums Victoria On Sunday afternoon, Sam's legs were still seeping blood but doctors had not found a cause. Sam said a nurse had suggested sea lice were to blame, "but it was just a guess". Bloody mess: Sam Kanizay in Emergency at Sandringham Hospital on Saturday night, his lower legs bloody after bathing in the bay at Brighton. Credit:Jarrod Kanizay

In winter of 2015, a suburban newspaper reported that Nick Murray and his son Will, 13, bled from their feet after standing in the bay at Sandringham for 10 minutes. The pair thought it was sea lice – marine parasites that feed on fish. 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. 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. Just be attracted to a little bit of blood. And if he's standing in the water and he's cold and may not notice a whole lot of little bites."

Have you been wounded by sea lice? Email us. Doina Canta, who goes swimming with the Icebergers swimming group every morning off the beach where Sam was injured, says it could be a sting ray. She said a man in her group was stung about six months ago on one leg, and had bled extensively. Sam Kanizay was still in shock on Sunday but it hadn't put him off swimming in the bay. "It was a bit of a freak thing to happen. I'm not really sure what to think of it." Jarrod Kanizay warned in an email that "something ate Sam's legs. If you are a member of the [Brighton] Ice Bergers or running groups that ice their legs at Brighton, then you may want to repost this to warn them to not stand still in it too long ... " A spokeswoman for Monash Health, which oversees Dandenong Hospital, said the patient was still being assessed and it was too early for a doctor to comment on the case.

Jarrod told The Age that at Sandringham Hospital "We had the emergency room full of everybody that was working there just fascinated, they were all on Google afterwards, hypothesising as to what happened. They pretty much had 10 different hypotheses but nothing yet." Jarrod said he and his friends often soak their legs after a run, "and I haven't seen this happen before". He said he was considering putting a bloodied piece of meat in the bay on Sunday night "to see if we can catch these things".