Wednesday June 25, 2025
The Conversation —
Imagine watching your favourite nature documentary. The predator lunges rapidly from its hiding place, jaws wide open, and the prey … suddenly goes limp. It looks dead.
For some animals, this freeze response – called “tonic immobility” – can be a lifesaver. Possums famously “play dead” to avoid predators. So do rabbits, lizards, snakes, and even some insects.
But what happens when a shark does it?
In our recent study, we explored this strange behaviour in sharks, rays and their relatives. In this group, tonic immobility is triggered when the animal is turned upside down – it stops moving, its muscles relax, and it enters a trance-like state. Some scientists even use tonic immobility as a technique to safely handle certain shark species.