You ever heard of the cookiecutter shark, Isistius brasiliensis? I hadn’t either until Phenomena’s Ed Yong told me about it today. "It’s a small cat-sized animal with chocolate-coloured skin, a rounded snout, and large green eyes. Beneath the bizarre head, its lower jaw contains what looks like a saw–a row of huge, serrated teeth, all connected at their bases," Yong wrote earlier this year. "When the cookie-cutter finds a victim, it latches on with its large fleshy lips and bites down with its saw blade. With twisting motions, it scoops out a chunk of flesh, leaving behind circular craters.
They have been known to attack great white sharks and killer whales and even nuclear submarines (the last of which suggests to me that they may not have the most developed nervous systems).
And in one case, and one case only, a human. This was noteworthy enough that researchers Randy Honebrink, Robert Buch, Peter Galpin, and George H. Burgess wrote this up in the journal Pacific Science: "First Documented Attack on a Live Human by a Cookiecutter Shark." And Deep Sea News’ Al Dove actually interviewed this human, a 65-year-old marathon swimmer named Michael Spalding. I run marathons, but I gotta say, marathon swimmers are crazy in an amazing way. Case in point: Spalding wanted to swim every channel between the main Hawaiian islands. He’d finished them all except the longest, Alenuihaha, which required more than 30 miles of swimming.