Have you ever heard the phrase ‘Thanatosis’ or ‘Tonic Immobility’? We certainly hadn’t until we filmed the Green Weevil below, seemingly playing dead upon being discovered.
We have to admit to being slightly baffled by this behavior. After all, how could this possibly help prevent a predator attack, or for that matter any other form of threat? A quick search online and we think we have the answer.
The act of thanatosis, or playing ‘feigning’ death, is apparently common in the animal kingdom, and many different phyla of animals exhibit this behavior. In invertebrates and in arthropods in particular, according to Wikipedia, the defensive purpose of tonic immobility is that many predators only catch live prey, so pretending to be dead deters certain would-be attackers. Although it should be added that different types of animals have different reasons to feign death, and this behaviour is different from that seen when scared animals, such as deer, freeze on the spot.
Interestingly, this is also common in many species of spiders, which upon reflection, we have probably witnessed without really thinking about it. Just think of the times you may have disturbed a spider and suddenly it is on its back, legs retracting to form a tight ball as if dead. Almost as if you had already killed it by accident.
Worth remembering next time you come across a seemingly dead arthropod, try to be gentle when putting it outside. Perhaps go steady with the old dustpan and brush, just in case it is only faking it.
DC: 12.06.2024
Wildlife Garden 