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In the animal kingdom, many animals possess a unique survival skill - "apnea". They remain motionless, appearing as if they are dead, in order to evade attacks from predators. In fact, this act of feigning death occurs in many animals, including birds, insects, reptiles, fish, and even some mammals. Whether an animal can successfully "pretend to be dead" and escape depends not only on how convincingly it acts like it's dead, but also on how the predator reacts.

Passive and active forms of feigning death exist. Active feigning death refers to when an animal deliberately pretends to be dead, using this method to deceive enemies or approach prey. For instance, some mustelid animals will feign death to approach bird prey, waiting until the prey relaxes before launching an attack. While passive feigning death occurs when an animal cannot escape a threat, they will involuntarily enter a state of feigning death. For example, North American opossums, when threatened, their bodies will become stiff, they may even emit a foul smell and lower their body temperature, resembling a decomposing corpse, thus causing predators to give up the attack.

Many carnivorous animals rely on whether the prey is moving to determine if it is alive. Like most mammals, during hunting, they pay attention to the movements and smells of the prey. For reptiles, fish, etc., they usually ignore those still prey. Many small animals and insects take advantage of this by feigning death to evade the attacks of predators. When they are in a state of apparent death, apart from not moving, their bodies also show some physiological changes, such as the eyes of opossums being half-closed, weak breathing, and stiff bodies, etc. These manifestations prevent predators from easily determining whether they are truly dead, thus giving up the attack.

The state of apparent death is not something that animals acquire through learning; rather, it is an instinctive reaction passed down through long-term evolution. Many animals, such as opossums, have their state of apparent death determined by genes and are "automatic responses" that do not require control by the brain's consciousness. This reaction is usually triggered automatically when they feel threatened, helping them escape from predators. Additionally, research has found that the state of apparent death in opossums has formed specific "reflex mechanisms". For instance, when they are turned over or their bellies are exposed, the state of apparent death will immediately activate.

Although feigning death is a genetically-driven behavior, the manifestations of different individuals still vary. For instance, the duration of the fake death and the speed of recovery can differ among individuals due to individual differences. These variations make it more difficult for predators to determine whether it is a "fake death" based on experience, thereby increasing the chances of the animals escaping.

Although feigning death is an effective defense strategy, it is not always 100% successful. For some predators with rich hunting experience and quick reactions, pretending to be dead may not work. Especially for some top predators, such as raptors and scavengers, they may not be influenced by this strategy.

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Which animals will feign death?

Virginia opossum

The Virginia opossum (Didelphis virginiana) in North America is an animal with remarkable survival wisdom. With a reproductive history spanning at least 20 million years, one of its core survival strategies is the superb state of hibernation. When an opossum senses a threat or potential harm, it exhibits a series of complex physiological and behavioral reactions: its lips are pulled back, its teeth are exposed, foam forms around its mouth, its eyes are closed or partially closed, and its anal glands secrete a strong foul-smelling liquid; its body may become stiff or distorted, and its facial expression shows extreme pain.

Even if it is handled or taken away by predators, the opossum remains completely motionless. Through this highly realistic "death performance", it can almost deter predators and prevent them from attacking. After a few minutes to several hours, the opossum gradually regains consciousness and resumes activity. Therefore, the opossum's state of hibernation can be regarded as the "Oscar-winning actor" in the animal kingdom.

Rabbit

The rabbit is a gentle herbivorous animal. Almost all animals of similar or larger size to it are its predators. Therefore, hibernation has become an important survival strategy for rabbits to deal with the threat of predation. When a rabbit is turned onto its back, its "hibernation switch" is triggered, causing it to enter a rigid state. At this time, its limbs are stiff, its eyes are closed, and its heart temporarily stops beating.

Shark

Such large and highly predatory creatures as sharks also possess a mechanism similar to the "pseudo-death" response within their bodies. When a shark is flipped onto its back, its head naturally secretes a specific chemical substance, causing it to enter a state of calmness. Through repeated flipping operations, the concentration of this substance in the shark's body gradually increases, leading it to enter a state similar to sleep or death, manifested by a stiff body and cessation of movement. This phenomenon is called "rigid immobility". In the study of marine animals, scientists sometimes use this reaction to "hypnotize" sharks, in order to suppress their aggressiveness and facilitate further research.

Mediterranean Cricket

This kind of cricket is very easy to raise, and thus is often used as food for animals such as reptiles and spiders. When Mediterranean crickets are caught by humans, they will bend their limbs and enter a completely stiff state. This "acting dead" behavior usually lasts for 2 to 4 minutes, and can even last up to 20 minutes. The hard leg spines of the crickets may cause some harm to small predators in this state. At the same time, this "acting dead" behavior helps reduce the risk of them being captured by amphibians and reptiles, as these predators are usually very sensitive to movement.

[The picture is from iNaturalist,the copyright belongs to the original author]

Domestic chicken

When faced with threats, domestic chickens also adopt a similar "playing dead" strategy. The duration of the chickens' "playing dead" behavior is usually related to the length of their companions' alarm calls: the longer the alarm call lasts, the longer the chickens' "playing dead" lasts.

Common green lizard

The common green lizard is native to India and Sri Lanka. When threatened, it usually pretends to be dead, showing the predator that it is already deceased. Then it suddenly escapes. This "pretending to be dead" strategy is very effective, as it can deceive the predator and give it time to escape.

Downing Sheep

This kind of rigid immobility is usually a passive response of animals to external pressure or threats. However, there is a kind of animal in the world that can enter this state autonomously, which is the "Dizzy Sheep" (Downed Sheep) from the United States. The uniqueness of this small sheep lies in that when frightened, they will immediately collapse and lie on their backs with their limbs stiff. The main reason for this phenomenon is that these sheep suffer from a genetic disease called "Congenital Myotonia".

When they fall down, their muscles will have a numb and stiff reaction, making them unable to move for a short period of time. It is worth noting that even without any external threat, these sheep may autonomously collapse nearly 30 times per week, which is a significant physiological burden for the animals themselves. Due to this characteristic, they have also become one of the most easily captured prey in history.

Eastern Bell Frog

The Oriental bell frog is mainly found in Asia and Europe. It protects itself by adopting a special "playing dead" posture. When threatened, it arches its body into a curved shape, twists its limbs, and the soles of its feet will show bright yellow or orange colors as a warning signal. Sometimes it will lie on its back, exposing the patterns on its abdomen. These patterns are actually related to the toxicity of its skin and serve as a reminder for predators not to approach easily. In fact, the name of the Oriental bell frog is derived from this defensive posture.

Forcing animals into a state of suspended animation is actually very dangerous for them. This state is not a complete relaxation of the body; many animals need to consume a lot of energy to maintain their rigid posture. For instance, rabbits in a state of suspended animation may suffer spinal damage due to prolonged stiffness, which could even lead to spinal fractures or other serious injuries, ultimately resulting in death. Moreover, the appearance of some animals' suspended animation is extremely realistic. If maintained for a long time, they may die from cardiac arrest or suffocation.