It’s a small fish, only a couple of inches long, and its bright colors make it pop in the Pacific coral reefs it calls home. The first thing that makes this fish peculiar is the striking pair of large lower canines it sports.

But when attacked by a predator, this fish, part of a group called fang blennies,does something even more strange. A predator that puts this fang blenny in its mouth would experience a “violent quivering of the head,” according to George Losey, a zoologist who observed this species up close in a series of feeding experiments in the 1970s. Then the predator would open its jaws and gills. The little blenny would swim away, unscathed.

A study published on Thursday in Current Biology now lays bare the details of the fish’s unusual defense mechanism: Unlike most venomous fish, which inject toxins through their fins, fang blennies deliver venom through their bite. Furthermore, fang blenny venom does not appear to produce potent pain, at least in mice. Instead, it causes a sudden drop in blood pressure, which might temporarily stupefy predators.