Weird Crafty Fish Can Make Itself Invisible

And We Don't Know How

The pirate perch (Aphredoderus sayanus) is a very strange creature: it's a small fish, only 5.5 inches long at most. Its cloaca (sort of a combination waste and reproduction opening) is right under its chin, it breeds by secretly dropping eggs into a mass of tangled wood, it'll eat anything in your fish tank (hence its name), and now it's exhibiting some exceedingly odd predatory behavior.

Crypsis is a method taken by animals to conceal themselves; in other words, they use camouflage. The pirate perch, though, isn't doing that. In fact, the researchers weren't really sure what the pirate perch is doing. The researchers suggest that it could be producing some chemical that blocks other animals from sensing it, which would make it the only known animal to use chemical crypsis.