How does a mouse play dead? - briefly
When threatened, a mouse freezes, stiffens its body, and lies motionless, often on its side, to resemble a corpse. This defensive strategy, called thanatosis, discourages predators that seek active prey.
How does a mouse play dead? - in detail
Mice employ thanatosis—a rapid, involuntary response that mimics death—when threatened by predators or sudden disturbance. The sequence begins with a sharp sensory cue, such as a predator’s movement or a loud sound, which activates the sympathetic nervous system. This triggers a cascade of physiological changes:
- Muscle inhibition: Motor neurons release increased gamma‑aminobutyric acid (GABA), causing a temporary shutdown of skeletal muscles. The animal collapses into a limp posture, often lying on its side or back.
- Respiratory suppression: Breathing rate drops to a shallow, irregular pattern, reducing detectable movement and sound.
- Heart rate deceleration: Parasympathetic signals lower cardiac output, conserving energy and limiting pulse detection by predators.
- Eye closure or reduced blinking: The mouse may partially close its eyes, further reinforcing the appearance of lifelessness.
Behaviorally, the mouse remains motionless for a period ranging from a few seconds to several minutes, depending on the intensity of the threat and species-specific tendencies. During this interval, the animal maintains a low metabolic state, minimizing heat signatures and odor emission.
Recovery follows the cessation of the perceived danger. The mouse abruptly reactivates motor circuits, resuming normal locomotion. This reawakening is often accompanied by a burst of sprinting to distance itself from the threat.
Research on laboratory strains and wild populations indicates that death‑feigning is more prevalent in environments where predation pressure is high. Observations have documented:
- Predator-specific triggers: Birds of prey and snakes elicit stronger thanatosis responses than mammalian predators.
- Age-related variation: Juvenile mice display longer immobility periods, likely due to higher vulnerability.
- Habitat influence: Dense underbrush and low‑light conditions increase the frequency of the behavior, as visual detection by predators is reduced.
The adaptive value lies in exploiting predators’ preference for live prey; many carnivores abandon motionless targets, assuming they are already dead or unpalatable. By temporarily presenting as non‑viable, the mouse gains a critical window to escape.