Which lizard squirts blood from its eyes as a defense?

The horned lizard is the lizard known for squirting blood from the corners of its eyes as a defense. When a predator gets too close, some species restrict blood leaving the head, sharply increasing pressure until tiny vessels around the eyelids rupture.

The resulting stream can travel several feet and is especially effective against canine predators such as coyotes, foxes, and dogs. The blood tastes unpleasant to these predators, which may drop the lizard and avoid attacking another one. The behavior is a last-resort defense, not the lizard’s first response.

Horned lizards also rely on camouflage, freezing in place, puffing up their bodies, and using their head horns and spiny scales to resist being swallowed. A common misconception is that every horned lizard can perform the trick: it is documented in at least eight Phrynosoma species, while several others cannot do it or do so only rarely. The Texas horned lizard is the best-known example.