Why Do Lizards Play Dead?

Lizards often play dead, a behavior known as thanatosis or tonic immobility, primarily as a last-resort defense to survive life-threatening situations.

During this state, their parasympathetic nervous system takes over, inducing a catatonic condition in which movement halts and vital functions, like heart rate, slow down.

Most lizards remain completely still for about 2 to 15 minutes, though stressed individuals may stay immobile for up to 30 minutes. Once the perceived threat leaves, the lizard quickly snaps out of the state and scurries away.

Many predators, such as birds, snakes, and cats, prefer hunting active prey. By freezing, slowing their heart rate, and appearing lifeless, lizards make themselves unappealing, prompting the predator to lose interest and move on. This behavior typically occurs after other escape strategies—like running or dropping their tail—have failed.

Many lizards can detach their tails to escape a predator and can regenerate them over several weeks or months. Besides evading predators, death-feigning has been observed in rare situations, such as males trying to mate or responding to extreme urban stress.

Predation serves as the major selective force that drives the evolution of various defense mechanisms in lizard species, limiting predators’ abilities to detect, recognize, and subdue their prey.

In fact, tail loss and locomotor escape represent the most common defensive behaviors documented in the literature. Some lizards, in response to external stimuli, exhibit thanatosis.

In a recent study, researchers reported the first observation of this behavior in a population of ‘Liolaemus occipitalis’ that inhabits coastal sand dunes in Southern Brazil.

Researchers tested a total of 86 individuals and found that 75.6% of the lizards feigned death when handled. The duration of this behavior increased when the observer remained closer, indicating that ‘L. occipitalis’ can effectively assess predation risk.

Content for this question contributed by Marylee Bunch, resident of Olmsted Falls, Cuyahoga County, Ohio, USA