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How is freezing different from tonic immobility during a predator encounter?
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Avoidance behaviour
Cat fleeing by upward climbing.
While both freezing and tonic immobility involve an animal becoming motionless when facing a predator, they serve different functions and occur at distinct stages of a predator encounter.1
- Freezing: This response is typically triggered as soon as an animal detects a predator. By suspending all movement, the animal aims to avoid detection entirely, thereby preventing the predator from noticing it in the first place.1
- Tonic Immobility: This is generally initiated only after a predator has already caught or is holding the prey. It is considered a basal, last-resort defense mechanism. The sudden state of extreme motor inhibition and apparent lifelessness may distract the predator or cause it to lose interest, providing the prey with a final opportunity to escape.1
In short, freezing is a proactive strategy used to remain hidden, whereas tonic immobility is a reactive, reflexive state used once capture has already occurred.1