Most sharks look the part of a big scary predator. The cookiecutter shark looks more like a brown sausage. It’s only about 20 inches long and lives in deep water during the day, rising near the surface at night to hunt. And its hunting strategy is one of the strangest in the ocean.
The cookiecutter shark glows faintly on its belly, so from below it looks like a tiny pinprick of light - easily mistaken for a small fish. When a bigger animal swims up to investigate, the cookiecutter latches on with its lips, twists its body in a quick spin, and removes a perfectly round chunk of flesh with its serrated lower teeth. Then it swims off, leaving a cookie-shaped wound.
Whales, dolphins, sharks, swordfish, and even submarines have shown up with cookiecutter wounds. A few unlucky open-water swimmers have too. The shark is basically a parasite with teeth - small, persistent, and weirdly precise.
