Blood squirt occurrence in the Mexican Plateau Horned Lizard (Phrynosoma orbiculare)

Abstract

Blood-squirting from ocular sinuses is a unique defensive behavior widespread in horned lizards. During an ecological study in the state of Mexico, Mexico, we captured 24 males and 23 females of Phrynosoma orbiculare, of which three males squirted blood during gentle handling. Two individuals were of juvenile size, suggesting, with data from large adults, that P. orbiculare defensive strategy may be employed throughout life.