A fungus causes cicadas to lose their limbs and 'try to mate with everything they encounter,' researchers found — here are 10 real examples of zombie animals in nature
- Zombies are ubiquitous in horror films, TV shows, and sci-fi novels.
- While the concept of reanimated corpses seems unrealistic, certain viruses and parasites in nature can cause animals to act in a zombie-like manner.
- Diseases such as rabies and sleeping sickness can cause an animal to behave in ways that are out of its control, and the stings of certain insects can cause their victims to act like undead slaves.
- A new study found that cicadas infected by one type of fungus lose their minds and go on a mating frenzy — even though the fungus causes their genitals to rot.
- Here are 10 examples of zombie-like phenomena in nature.
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Zombies are ubiquitous in popular culture — the undead appear in everything from Mary Shelley's "Frankenstein" to TV shows like "The Walking Dead." Even the White Walkers in "Game of Thrones" raise an army of undead wights: corpses that have been reanimated with magic and kill on command.
Zombies are typically defined as will-less, supernaturally reanimated creatures that behave in markedly strange ways. Although a zombie apocalypse may seem outside the realm of plausibility, more than a handful of real viruses and parasites can cause members of the animal kingdom to act like the undead.
The most recent example: A study published in the journal Fungal Ecology reports the discovery of a fungus that infects cicadas, causing their abdomens and genitals to fall off. Despite these missing body parts, male cicadas "try to mate with everything they encounter" before dying, the researchers reported. The fungus contains chemicals similar to those found in hallucinogenic mushrooms, and is transmitted to cicadas via spores in the air.
Other parasites and diseases that cause animals to act like zombies are passed through bites or bodily fluids. Chronic wasting disease, which affects an animal's brain and central nervous system, is one such example. (This type of transmission often appears in fictional stories, like the movies "I Am Legend" and "28 Days Later.")
Read more: 'Zombie deer disease' has now hit 24 US states. You could be eating infected meat without knowing it.
Here are 10 ways animals can turn into something akin to a zombie.
The Massopora fungus contains psychoactive compounds and rapidly consumes infected cicadas' butts, abdomens, and genitals. Despite that, the insects' libido skyrockets, and they "try to mate with everything they encounter," the researchers said.
Zombie deer disease affects an animal's brain and nervous system. Infected animals' bodies waste away as they lose weight at a rapid pace, and they eventually begin to stumble around confused, drooling and listless — hence the zombie moniker.
Although no deer-to-human transmission has been reported yet, experts are concerned that it could happen.
Other neurodegenerative prion diseases have affected humans in the past. Mad cow disease is one example, as is a disease called "kuru" that spread among the Fore people, an indigenous tribe in Papua New Guinea, during the 1950s and 1960s.
The Fore were known to ritually prepare and eat the brains of deceased relatives, but that sparked a kuru outbreak, according to NPR. The disease seemed to spread from infected brain tissue. People who contracted the disease lost the ability to control their limbs and bodily functions.
Rabies is a viral disease typically transmitted by the bite of an infected animal. It spreads when an infected creature's spit gets into another animal's blood, eyes, nose, or mouth.
Rabies starts off rather innocuously with flu-like symptoms, but it can become fatal. If left untreated, the virus causes swelling in the body's central nervous system (the brain and spine), which leads to more severe physical symptoms, including paralysis, seizures, and muscle spasms that can cause unusual postures.
As the virus progresses, it causes animals to behave abnormally and impairs their balance and coordination. They hyper-salivate and have trouble breathing and swallowing. Sometimes, rabies-infected creatures will act aggressively or even mutilate themselves.
Raccoons, skunks, foxes, coyotes, and some bat species can carry rabies. These animals can pass it to dogs, cats, and even humans.
Every year, 55,000 people die from rabies around the world. Fortunately, the rabies vaccine is 100% effective post-exposure if it is administered before serious symptoms manifest.
African sleeping sickness is caused by parasites transmitted by the bite of the tsetse fly in Africa.
The disease can affect many types of mammals, including cattle, sheep, elephants, South African white-tailed deer, primates, and humans. Infected animals and people become listless and emaciated, losing hair and becoming weaker until paralysis sets in.
The most notable symptom of sleeping sickness, which gives the disease its name, comes after the parasite has invaded the brain: Infected people are unable to sleep at night and can't stay awake during the day.
Those who get the disease also experience fevers and muscle aches, followed by mental deterioration, personality changes, and problems with walking and balance if it's left untreated. There is no vaccine to prevent sleeping sickness, but several drug treatments are available for infected patients.
"Victims find it hard to concentrate. They become irritable, their speech is slurred and they stop eating," Sanjeev Krishna, a professor of medicine at the University of London, told the BBC, adding, "this is an infection that carries nightmarish qualities, reducing many of its victims to a zombie-like state before they go into a coma and die."
A fungus called Ophiocordyceps unilateralis, which is found in the jungles of Brazil, reproduces and spreads by hijacking the minds of nearby carpenter ants.
According to a 2014 study, the parasitic fungus infects the ant with deadly spores, which release chemicals that enable the fungus to take control of the hapless insect's nervous system.
The fungus forces the ant to climb up a plant to the exact level of height and humidity that the fungus needs to grow. Then it leads the ant to clamp its jaws around a leaf before killing the unwilling puppet.
After that, the fungus grows inside the dead ant's body, eventually pushing a long stalk out of the dead insect's head. The stalk releases more spores that infect new ants.
The emerald cockroach wasp, also known as a jewel wasp, can manipulate cockroaches' behavior, forcing them into servitude.
According to a 2014 study, this wasp first paralyzes its victim with one sting, then stings the helpless roach a second time, inserting its stinger into the roach's brain with surgical precision.
This gives the wasp complete control over the cockroach. The bug eventually regains its ability to move, but it can no longer initiate its own actions; the wasp controls its body and mind.
The wasp then lays its eggs in the zombie roach's abdomen.
Other species of wasps are also known to sting cockroaches then lay eggs in their victims' abdomens. But the jewel wasp's brain-control tactics are the most sinister.
Pill bugs — also known as potato bugs or roly polies, though the more accurate term is wood louse —sometimes ingest and become the unwitting hosts of parasitic worms called acanthocephalans.
The parasite needs to get inside a bird's digestive tract to mature fully. So the parasite takes over an unfortunate bug's brain, grows inside it, and prompts the insect to make itself readily available as bird food.
The worm forces the bug to expose itself in broad daylight, instead of staying safely curled up under a rock or stump. It also leads the bug, which is darkly colored, to meander onto a lightly colored surface, where birds such as starlings can see it better. Then the mind-controlled insect waits to be eaten, and the parasite eventually makes its way to its preferred growing place.
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The Zatypota wasp lays its egg in the abdomen of an Anelosimus eximius, a type of social spider, according to a 2018 study.
The spider is known to cooperate with thousands of family members in a communal home, sharing hunting, parenting, and feeding duties. But after becoming the wasp's victim, the spider's behavior changes.
Once the wasp's deposited egg hatches, the larva attaches itself to the spider and forces its victim to move away from its communal nest. The spider then creates a cocoon-shaped web of its own, and the larva feeds on its spider victim's blood until the arachnid dies.
The parasitic Hymenoepimecis argyraphaga wasp in Costa Rica lays its eggs in the abdomen of the orb-weaver spider. The wasp larvae hatch and leach nutrients from the spider for a couple of weeks, then inject their host with a chemical that leads it to construct an extremely strong web.
Once the web is complete, the larvae kill and eat the spider. They then use the strength of its web to support their own cocoons and enjoy a silky residence that's safe from predators.
Instead of attaching themselves to rocks, Sacculina carcini barnacle larvae settle onto crabs' abdomens. They inject the crab with a parasite that slowly spreads through the unwilling creature's body and takes over its brain.
The barnacle then castrates the crab, and the crustacean becomes the home of new baby barnacles before the parasite fully kills it.