Sea bug attack: Why was a wading teenager left covered in blood?
Mr Kanizay sent samples to marine biologists at Museums Victoria, who identified them as a species of crustacean called the amphipod, or sea flea, mostly likely from the lysianassidae family.
However another expert, Dr Murray Thomson from the University of Sydney, said he believed the creature was another type of crustacean, an isopod called cirolana harfordi.
Amphipods feed largely on dead marine animals such as fish and crabs, and are themselves prey for larger marine animals.
"If we did not have them, we would have a sea full of dead fish and dead birds," Dr Genefor Walker-Smith, the marine biologist who viewed Mr Kanizay's sample, told the Australian Broadcasting Corp.
Dr Thomson said isopods also eat mainly dead fish and marine worms, as well as living fish.
Both amphipods and isopods are mainly active at night.
It was most likely a combination of factors, including time of day and cold water numbing Sam's skin, according to experts.
The teenager has described standing for about 30 minutes before feeling pins and needles around his ankles, then shaking off what he initially took to be sand.
Associate Prof Richard Reina, from Monash University, described the case as very unusual.
"It's only when you get the potential for hundreds or thousands of them to start biting you, for a long period, that you get the type of injury that Sam had," he told the BBC.
"Unless you're effectively numb, [usually] you're going to notice and get out of the water before that happens."
Dr Walker-Smith said it is possible that Sam may have interrupted the animals feeding on something else.
The teenager and his family have said it took time for the blood to clot, and that on Monday it was "still seeping".
Assoc Prof Reina said this was probably due to tissue damage caused by having so many small bites.
He likened Sam's ordeal to being bitten by mosquitoes or leeches.
"If you imagine that you had your arms exposed somewhere and you had hundreds of mosquitoes biting your arm, without you realising it for some reason, then they could probably cause some fairly significant wounds as well," he said.
Not according to experts, who say small crustaceans are found in abundance - making this incident an "unfortunate coincidence".
Dr Walker-Smith said it was much more likely for someone to suffer bites on a smaller scale and have only minor irritation.
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