Thanatosis or tonic immobility is a term used to describe the tactics of playing the dead that some species of animals use for different purposes. Some will pretend to be dead to lure potential prey, while others will pretend to be dead when faced with a mortal threat themselves. In this article, we will discuss nine animals that pretend to be dead in order to survive contact with a predator, and all of these animals have a unique characteristic.
# 9 Virginia Opossum
Opossum Virginia (Didelphis virginiana) – the creature on which the distinctive phrase of the possum game is based. This animal is the only marsupial found in the United States and Canada, and they are often called possums, although they belong to a completely different genus. Also known as the North American possum, these kangaroo cousins have put a lot of effort into their game.
When threatened by a lynx or other predator, opossums rush on their backs, baring their teeth, drooling from their mouths, and secreting extremely fetid fluid from their anal glands in an attempt to avoid mortal danger. These actions often lead people to suspect that the possum may have rabies, but in reality they are just a natural defense mechanism. Opossums are also scavengers, and this behavior can be life-threatening when frightened by cars during a murder investigation and pretending to be dead in the middle of the road.
# 8 Texas indigo snake
Texas indigo snakes (Drymarchon melanurus erebennus) are a subspecies of the eastern indigo snake, and are known to also pretend to be dead. These snakes can grow up to 7 feet in length and are found throughout Texas. They are not poisonous or constrictors, and they have to rely on their muscular jaws to overpower and swallow food head first. Texas indigo snakes hunt even venomous rattlesnakes and are immune to their venom.
Cases have been reported of these large snakes being threatened, rolling their bodies freely and becoming immobile. They even open their jaws to look relaxed. If they are manually manipulated during thanatosis, they rotate their body to remain with their belly down, but otherwise they will remain motionless.
# 7 Ducks
Many species of ducks feign death when faced with perceived dangers, including the famous North American forest duck (Ex-sponsor) and mallard (Anas flat-lipped). Researchers have documented that 29 out of 50 different wild ducks pretended to be dead when exposed to red foxes in captivity. This immediate fall at least gives the duck a chance to fight if the fox loses its vigilance.
It has also been found that ducks can stay in place long enough to even be returned to the fox’s lair to try to escape later. The veteran foxes quickly realized that they needed to inflict fatal or serious injuries even on ducks that appeared dead due to the prevalence of thanatosis among these species.
# 6 Lemon shark
The lemon shark (Negaprion brevirostris) is interesting because it is a top predator, but at the same time it is one of the animals that pretends to be dead. If the lemon shark is turned over on its back, it will not only play a possum, but it will also begin to show shortness of breath and periodic tremors. This is especially interesting when you consider that the lemon shark is known to lie on the ocean floor and allows other animals to remove parasites from their bodies. They can remain perfectly still and pump water through their gills to breathe.
Lemon sharks prey on many species of fish, rays and even other sharks. The fact that they also use tonic immobility is striking as they do not come into contact with significant natural predators. However, they are also far from the only shark species with tonic immobility.
# 5 Rabbits
Both domestic rabbits and rabbits in the wild have shown thanatosis, but this is not entirely surprising given their status as carnivorous animals. Domestic rabbits used as pets (Oryctolagus cuniculus) are sometimes introduced into a trance by their owners. This exploits the rabbit’s natural survival instinct as something that creates the appearance of affection or relaxation.
In fact, rabbits spend most of their time with their paws on the ground. If they find themselves in a position where they cannot escape, then they will exhibit tonic immobility as a defense. What is considered a form of hypnosis is actually an extension of their natural fight or flight reflex and can even cause stress in the animal. Researchers confirmed this stress by monitoring the heart rate and respiration of rabbits in this condition.
# 4 Dwarf grasshopper
Dwarf grasshopper (Criotettix japonicus) demonstrated a unique version of the possum game when facing danger. They freeze completely, like the rest of our list, but in addition, they also spread their legs as far as possible in all directions and make them stiff. This makes it almost impossible for predatory frogs to even try to swallow them.
These grasshoppers are native to Japan, and this one-to-one approach to death simulation perfectly matches the threats they are likely to face. The predation of the so-called “sedentary” hunters would make grasshoppers vulnerable if they simply pretended to be dead without additional obstacles in the form of stretching all parts of their body in all possible directions. This prevents the frog from swallowing them immediately and significantly increases the chance of survival of the grasshopper.
# 3 Red spider
Red-backed spider (Latrodectus hasselti) is a close relative of the black widow spider, and they are equally deadly to humans. Fortunately, these spiders are not aggressive towards humans, so most bites occur when spiders get caught between clothing or shoes and their skin. Redbacks are also known to be more aggressive in protecting their eggs. Both sexes of spiders bite with the same frequency, but the female is responsible for a much larger number of cases when the victim receives a dose of venom.
Given its more docile nature, it should come as no surprise that this spider is more likely to respond with tonic stillness when it senses danger outside of its web. Red-backed spiders are one of those animals that pretend to be dead, curl up into a ball and remain completely frozen. These spiders are native to Australia, but migrated to New Zealand, Japan and several other countries through fruit imports.
# 2 Eastern hognous snake
Eastern pork snake (Heterodon Platyrchinos) is the second snake to make our list, and this one does a much better job of selling the act. Hognous snakes are found all over the world, and they all commit thanatosis. The eastern boletus is primarily found in the eastern half of the United States and prefers forests.
Although they grow up to 46 inches in length, these snakes put on a show when faced with what they think is dangerous. The Eastern Ferocious Snake first begins to writhe back and forth as if in pain, and at the same time gives off an extremely unpleasant odor. After a while, the snake falls on its back, slightly opening its jaws, and lies motionless. It will remain in this state for some time, even if you touch or handle it.
# 1 Anthill
Ant lions are insects known for their extremely aggressive and predatory larva and equally impressive possum play. Having literally many species that can be called by this name, we are specifically talking about our Euroleon… This nest was spotted by researchers playing the possum for 61 minutes. All ant lion species feign death, but this level of commitment to tactics deserves special mention.
In the United States, ant lion larvae are called “pigs”. They are predators that attack from holes or hiding places and suck the insides of their victims. These larvae are so aggressive because they need to consume enough food to support the adult evolution of the species, since they do not eat after their transformation is complete.
There are so many animals that pretend to be dead in the face of danger that this list is only sketchy. The vast majority of insects experience tonic immobility in one way or another, and there is still a whole group of wild animals playing possums for other reasons, for example, for more efficient hunting or mating.
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