by Greg Mayer

Appropriately following upon Jerry’s monstrous, triffid-like seed pod,  an attack by tiny monsters on an Australian teenager has been splashed across world media, including the BBC and the New York Times. The victim, Sam Kanizay was cooling off after a football match by wading in the sea near Melbourne. After a half hour in the water, he emerged bleeding profusely from the ankles, and the bleeding did not readily stop. He was taken to the hospital and should be just fine.

The interesting question from a biological point of view is “What did this to him?” We have a natural history whodunit, with two contenders, both crustaceans, and both quite small: isopods or amphipods. The BBC, citing Genefor Walker-Smith, said it was amphipods. The Times said the consensus was that it was isopods. Sam’s father Jarrod put some meat out in the water, and collected a host of critters, and posted a video of them to Youtube.

Most people in the north temperate zone are probably familiar with what we call in New York “cement bugs”, but are known by many other names: sow bugs, pill bugs, rollie pollies, etc. These are isopods, and there are marine ones called sea lice. Amphipods are less familiar in the Northern hemisphere, as they are aquatic and marine, and thus less commonly encountered. (There are terrestrial ones in the Gondwanan continents.) The ones that live at marine beaches are called sand fleas. One way to tell at least the usual ones apart is that isopods are dorso-ventrally compressed (‘squashed’ from above); while amphipods are laterally compressed (‘squashed’ from the side), and typically lay and move about lying on their sides. Both are said by the news reports to occasionally bite people.

In the video, you can clearly see that the critters are amphipods– pause the video, and enlarge on the screen if necessary, to see this. The Times quotes Alistair Poore, of the University of New South Wales, as also saying the critters are amphipods. However, although Jarrod trapped them by using meat as a bait, it’s not certain that what he trapped are the same things that bit Sam.