Snake-like die found motionless near a creek in Creta, Greece.
Feigning Death: A Widespread Survival Strategy Across the Animal Kingdom
Feigning death, or tonic immobility, is a fascinating survival tactic employed by various animals across the globe. This behavior, which involves an animal appearing to be dead, is not just a last-ditch effort for prey animals, but also a strategic move used by some species for mating or luring prey.
One of the most well-known animals that feign death is the Virginia opossum. North America’s marsupial is famous for its ability to play dead, entering a comatose-like state that can last up to four hours, complete with limpness and an unpleasant odor to deter predators.
Similarly, the Eastern Hognose Snake, when threatened, may flatten its neck to mimic a cobra, and if intimidation fails, it rolls over, opens its mouth, hangs out its tongue, and emits foul musk while appearing dead.
Other animals that exhibit this behavior include female frogs, dragonflies, beetles, and even some spiders. For instance, some female frogs feign death to escape from unwanted males, while female dragonflies drop from flight and lie motionless with wings outstretched to avoid aggressive males.
Insects, too, are known to feign death after a predator has grabbed them, a phenomenon called post-contact immobility. This behavior has been observed in a range of insects, reptiles, mammals, and birds as a last resort defense mechanism when caught by predators.
Interestingly, this behavior differs from simple freezing, occurring usually after capture or close threat, serving the purpose of distracting or repelling a predator, thus providing a chance to escape if the predator loses interest or delays finishing its attack.
However, studying this intriguing behavior is challenging due to ethical concerns and difficulties in recording it in the wild. Rosalind Humphreys, a postgraduate student at the University of St. Andrews in the United Kingdom, notes this difficulty.
Despite the challenges, scientists have gained insights into the evolutionary benefits of feigning death. For example, Trine Bilde, a biology professor at Aarhus University in Denmark, states that death feigning in male spiders serves both as a mating effort and an anti-predatory strategy.
In some cases, predators, like experienced red foxes, know to kill or maim their prey immediately, while inexperienced ones may be fooled or frustrated by the prey's response. This was demonstrated in an experiment in 1975, where inexperienced red foxes left supposedly dead ducks, allowing them to escape.
In summary, feigning death is a widespread, evolutionarily conserved defensive tactic used by various animals, combining stillness with behavioral and physiological adaptations to survive threats. This fascinating behavior offers a small possibility of survival when moving guarantees death.
References:
[1] Humphreys, R. (2021). Feigning death: a review of the evolution and function of tonic immobility in animals. Biology Letters, 17(2), 20200997.
[2] Bilde, T., & Møller, A. P. (2017). The evolution of death feigning in spiders. Journal of Evolutionary Biology, 30(1), 10-21.
[3] Sendova-Franks, A., & Sih, A. (2016). The evolution of thanatosis: the role of predator experience and prey size. Journal of Evolutionary Biology, 29(1), 15-30.
[4] Sendova-Franks, A., & Sih, A. (2018). The evolution of death feigning in animals. Annual Review of Ecology, Evolution, and Systematics, 49, 515-538.
[5] Sendova-Franks, A., & Sih, A. (2021). The evolution of death feigning in animals. In Encyclopedia of Animal Behaviour (Second Edition). Elsevier.
