Certain animals, including the Montpellier snake, simulate death because many predators lose all interest in prey that already seems dead: this total immobility, called thanatosis, is an involuntary physiological reflex triggered by extreme stress, and not a strategy thought out by the animal.
A nervous reflex, not a decision
Faced with a predator that it cannot escape, the Montpellier snake can turn on its back, its mouth half open, its body limp and immobile, sometimes for several minutes. This behavior, documented in several colubrids, results from a discharge of the autonomic nervous system which causes a sort of catalepsy: slowed heart rate, almost zero muscle tone, lack of reaction to stimuli. The animal does not “choose” to freeze: it is a reflex mechanism comparable to a defensive fainting, beyond any voluntary control.
The effectiveness of this tactic is based on a simple principle in many predators, notably birds of prey and certain carnivorous mammals: they are programmed to spot movement and often lose interest in inert prey, as a health precaution or because their capture instinct relies mainly on detecting an escape. By remaining completely still, the snake therefore reduces the risk of being killed or carried away.
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A smell that reinforces the illusion
In several reptiles practicing thanatosis, immobility can be accompanied by smelly cloacal secretions, which accentuate the impression of a decomposing corpse and further discourage the predator from consuming the prey. This olfactory signal, although less studied specifically in Malpolon monspessulanus than in other European snakes, follows the same logic: deterring an occasional scavenger rather than an active predator, by playing on its natural aversion to flesh already damaged by putrefaction.
The exit from this state is also automatic: as soon as the threat recedes sufficiently, the animal suddenly resumes movement and flight, without a conscious transition phase, confirming that it is a hard-wired survival mechanism rather than an elaborate ruse.
