It is a behavior of defense of certain animals, which simulate the own death to deceive predators.
Practitioners include some mammals (such as possums), reptiles (lizards and snakes), amphibians (toads and tree frogs) and even fish. Brazilian examples are the crab Trichodactylus panoplusthe lizard Liolaemus occipitalis and the frog Physalaemus kroyeri.
A «interpretation» of the animals is worthy of an Oscar. “They don’t just cease their movements. Some drastically reduce tactile perception, susceptibility to pain, heart rate or breathing rate. Some snakes and skunks even exude a strong nauseating smell”, explains the biologist Eliane Gonçalves de Freitasfrom the São Paulo State University Júlio de Mesquita Filho (UNESP).
This state can last from about 60 secondssuch as the cane toad (physalaemus centralis), to unbelievable 30 minuteslike the spider Hoplobunus mexicanus!
Necrophilia?
The male spider Pisaura mirabilis uses thanatosis to make himself more attractive to his partner. And the fish Haplochromis livingstoni, for hunting.