Tom Phillips
Tom Phillips

8 Parasites that Create Zombie Animals

Tom Phillips
Tom Phillips

Five years ago, I wrote The Invasion of the Zombie Animals and 7 More Zombie Animals. Those two lists covered the best-known cases of parasitic creatures that take over the minds and bodies of other animals for their own selfish ends. But there are many more such parasites that do exactly the same thing. They give us nightmares and feature films, but life is even worse for their victims.

1. Zombie Fish Has a Hot Flash


Photograph by Solveig Schjorring.

The bird tapeworm Schistocephalus solidus uses three hosts in its life cycle. Its eggs are laid in a bird’s digestive system. When the eggs reach the water in bird droppings, they hatch into larvae, which are eaten by copepods, a type of crustacean. The copepods are eaten by stickleback fish. This is where the tapeworm wants to grow large. Through some chemical mechanism, the tapeworm changes the fish’s behavior. The fish no longer stays with its school, but swims to the warmer water preferred by a growing tapeworm. Leaving the other fish also make the stickleback more likely to be eaten by a seabird, which is where a mature tapeworm wants to be in order to lay its eggs. And the cycle can start all over again.

2. Zombie Honeybees Head Toward the Light


Photograph by Core A, Runckel C, Ivers J, Quock C, Siapno T, et al.

Apocephalus borealis is a fly that lays its eggs in bumblebees, but has been observed to use honeybees as a host more recently. This makes it a suspect in the widespread Colony Collapse Disorder. The fly lays its eggs in the bee’s body, and the infected bee stops working and abandons the colony. Its behavior becomes more like a moth in that it tends to move toward lights, throwing off its navigation. However, while a moth flies around a light, infected honeybees will stagger and fall down. The bee eventually dies when the fly larvae burst out from behind its head.

3. Zombie Caterpillars “Plant” Themselves


Photograph by L. Shyamal.

Ophiocordyceps sinensis is a parasitic fungus that is actually classified as an endangered species. It lives in soil, but eventually reproduces with the help of a ghost moth caterpillar. The infected caterpillar will “plant” itself in soil, with its head pointing toward the surface. The fungus grows over winter, digesting the caterpillar from the inside. In the spring, a fruiting body will burst through the caterpillar’s head and “sprout” above the soil. Often the “stalk” of fungus will be bigger than the caterpillar itself.

The fungus grows only in Tibet and the Himalayas, where the dead infected worms are collected and sold for medicinal use under the name yartsa gunbu. It’s not easy to harvest, but a pound of it can bring $50,000. Overharvesting led to the endangered classification

4. Zombie Spiders Become Tailors


Photographs by Stanislav Korenko and Stano Pekár.

Czech scientists Stanislav Korenko and Stano Pekár describe the effects of a parasitic wasp, Zatypota percontatoria, on the spider Neottiura bimaculata. The tiny wasp will inject an egg into the abdomen of the spider. The egg hatches and feeds on the spider. The zombie mind-control only occurs when the larva is almost mature: that's when the spider stops its normal web-spinning pattern (B in the above picture) and begins spinning a different kind of web (A) -one that is a perfect place for a wasp cocoon, with a platform to keep it off the ground and a hood to shield it from the weather. When the “customized” web is ready, the larva bursts from the spider, killing it, and spins its own cocoon in the web (C and D).

Another species of spider affected this way is Anelosimus octavius, which is a “tangle web spider.” It produces a rather unstylish web until infected by a wasp of the genus Zatypota. Then it is directed to build an elaborate tent for the parasitic wasp’s cocoons. See the affected webs here.

Yet a third pairing of spiders and wasp parasites was covered in the second list in this series.

5. Zombie Crickets Shoot Blanks


Photograph by Flickr user Tom Phillips.

The virus IIV-6/CrIV is a sexually-transmitted disease that affects crickets. But this virus has a trick up its sleeve- it affects the behavior of crickets for its own ends. A cricket infected with IIV-6/CrIV will become more sexually active than a non-infected cricket, which facilitates the spread of the virus from one host to another. The crickets, however, become sterile, both male and female, which means they will continue to mate until they die. The virus does not make the crickets feel sick, though, because that would be counterproductive to sexual activity. If an STD could be thought of as sentient, this one would be a genius.

6. The Zombie Drug-addict Ant Slaves


Photograph by Alexander L. Wild.

The Central American acacia tree and the ant Pseudomyrmex ferrugineus live in a symbiotic relationship. The tree provides sweet nectar for the ants, and the ants protect the tree from weeds and animals. But we now know that the relationship is rather one-sided, as the tree not only causes the ants to become addicted to its nectar, but also damages the ants to make them unable to digest any other food! Martin Heil of Cinvestav Unidad Irapuato in Mexico studied the ants, and found that they are born with the ability to digest a variety of sugars, but then lose their invertase, an enzyme that breaks down sugars. The disabled ants can then only survive on the partially-digested sugar of acacia nectar.

Heil has now shown that the tree itself is responsible. Writing in the Ecology Letters journal, he reports that acacia nectar contains chitinase enzymes that completely block invertase.

Shortly after the workers emerge from their pupae as adults, they take their first sip of nectar and their invertase becomes irreversibly disabled.

That's kind of like a nefarious baby food company that offers to pay for your rotten teeth to be pulled instead of repaired. Like I've always said, never trust a tree bearing gifts.

7. Brainless Zombie Ants Carry On and Bury Themselves


Photograph by S.D. Porter, USDA-ARS.

Pseudacteon litoralis is a parasitic fly that victimizes fire ants in South America. The female fly lays an egg in the ant’s body with an ovipositor that resembles a hypodermic needle. The egg hatches inside the ant, and then the larva works its way to the ant’s brain, which it eats. The rest of the colony doesn’t even notice that the infected ant no longer has a brain, because the fly larva causes the ant to keep on working and behaving as always! That is, until the larva matures into a pupa. Then it causes the ant to go off by itself and snuggle down in a bed of forest litter, very un-antlike, for the climax of the story. That’s when the mature fly pops off the ant’s empty head and emerges from the dead body to fly off and reproduce.

8. The Meta Parasite


Photograph by Andy Potter.

Just because a wasp is a parasite that feeds off other insects doesn’t mean it has no natural predators. They can become victims themselves! Parasites that feed on other parasites are called “hyperparasitoids.” Ed Yong says, “It’s like a cross between the films Alien and Inception.” This story involves not only a caterpillar and two (or more) parasites, but also a cabbage that communicates.

When a cabbage begins to be eaten by a caterpillar, it emits a chemical signal, like an alarm. The scent of the chemical summons the parasitic wasps Cotesia rubecula and/or Cotesia glomerata, which infect the caterpillar with their eggs. This benefits the cabbage in the long run by controlling the cabbage-eating caterpillars. But the chemical also attracts the wasp Lysibia nana, which lays its egg in the Cotesia grub that is already feeding off the still-living caterpillar! Now, the L. nana wasp can tell which Cotesia species is inside the caterpillar, because the grub changes the chemical composition of its host’s saliva, and L. nana can smell the difference. It prefers a caterpillar infected with C. glomerata. One hypothesis is that C. rubecula has evolved to alter the caterpillar’s saliva more subtly for the purpose of hiding from the the hyperparasitoid L. nana.

But of course, the L. nana wasp is vulnerable to yet other meta-parasites. None are safe.

See also: The Invasion of the Zombie Animals and 7 More Zombie Animals.

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IKEA
IKEA Is Recalling Its New Dog Water Fountain Due to Suffocation Risk
IKEA
IKEA

In late 2017, IKEA released LURVIG, its first-ever line for pets, a collection that included beds, leashes, food bowls, and other staple products for dogs and cats. Unfortunately, one of those products is now being recalled over safety issues, according to Fast Company. If you own the LURVIG water dispenser, you should take it away from your pet immediately.

The automatic water fountain poses a suffocation hazard, the company announced in a recent statement. The retailer has received two reports of pets dying after getting their head stuck in it.

A water fountain for pets sits next to a bowl full of dog food.
IKEA

The $8 water dispenser debuted in U.S. stores in October 2017 with the rest of its LURVIG line. Awkwardly enough, the product description included assurances of the product’s safety standards. It explained that “the LURVIG range was developed with the assistance of trained veterinarian Dr. Barbara Schäfer, who also works with product risk assessment at IKEA,” and went on to say that “the first thing to consider was safety: ‘Dogs will definitely chew on their toys and bring in dirt from their daily walks. Cats will definitely scratch on most surfaces and are sensitive to smell and texture. So safe, durable materials are very important.’”

It seems that smaller dogs are able to get their faces stuck in the dome-shaped plastic reservoir, which only appears to have one hole in it, at the bottom. As a result, dogs can suffocate if they can’t get out of it.

The product has been removed from IKEA’s website, and the retailer recommends that anyone who bought it stop using it and return it to the nearest IKEA store for a refund.

[h/t Fast Company]

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Alamy
10 Facts About the Portuguese Man O' War
Alamy
Alamy

Something a lot scarier than any Jersey Devil has been washing up on beaches in the Garden State lately: This month, the dangerous Portuguese Man O’ War—which has a potentially deadly sting—has been sighted in Cape May and Wildwood, New Jersey, which could lead to problems for beachgoers. Read on to learn more about these unusual creatures.

1. IT'S NOT A JELLYFISH.

The Portuguese Man o’ War may look like a bloated jellyfish, but it’s actually a siphonophore—a bizarre group of animals that consist of colonies made up of dozens, hundreds, or even thousands of genetically-identical individual creatures. A siphonophore starts out as a fertilized egg. But as it develops, it starts "budding" into distinct structures and organisms. These tiny organisms—called polyps or zooids—can’t survive on their own, so they merge together into a tentacled mass. They must cooperate as one in order to do things like travel and catch food.

Though the zooids within a Man O’ War are basically clones, they come in different shapes and serve different purposes [PDF]. Dactylozooids are long hunting tentacles built to ensnare prey; gastrozooids are smaller tentacles which digest the food; and gonozooids are dangling entities whose job is to facilitate reproduction. Every Man O’ War also has a pneumatophore, or “float”—an overgrown, bag-like polyp which acts as a giant gas bladder and sits at the top of the colony. Capable of expanding or contracting at will, it provides the Man O’ War with some buoyancy control. An expanded float also enables the colony to harness winds to move around.

2. A CLOSE RELATIVE IS THE INDO-PACIFIC “BLUEBOTTLE.”

A view of a bluebottle under water.
iStock

When we say “Portuguese Man O’ War,” we’re talking about Physalia physalis, the bizarre siphonophore that’s scaring New Jerseyans right now. Also known as the Atlantic Portuguese Man O’ War, it can be found in warmer parts of the Pacific, the Caribbean, the Indian Ocean, and of course, the Atlantic.

Another kind of siphonophore which regularly stings beachgoers is the so-called bluebottle, Physalia utriculus. It’s sometimes called the Indo-Pacific “Portuguese” Man O’ War and is restricted to the Pacific and Indian Oceans. It’s smaller than the Atlantic species and unlike its bigger counterpart—which has multiple hunting tentacles—it hunts with a single, elongated tentacle.

3. THE NAME “PORTUGUESE MAN O’ WAR” IS PROBABLY A NAVAL REFERENCE.

In the age of sailing, many European navies used tall warships loaded with cannons and propelled by three masts. British sailors took to calling this kind of vessel a “Man of War.”

What does that have to do with Physalia physalias? These colonies spend a lot of time floating at the water’s surface, and when the gas bladder is expanded, it looks—and acts—a bit like a sailboat, hence the “Man O’ War.” As for the Portuguese part, 19th century scientists proposed that sailors encountered it near the Portuguese island of Madeira, while modern etymologists tend to think that it looked like the Portuguese version of the ship.

Or at least that’s one explanation for the creature’s peculiar name. It’s also been suggested that Renaissance-era sailors thought the pneumatophores resembled the helmets worn by Portugal’s soldiers during the 16th century.

4. MAN O’ WAR TENTACLES CAN BE UP TO 165 FEET LONG.

Two Portuguese Man o' War washed up on the beach with their tentacles stretched out.
iStock

At least, that’s the maximum length for the dactylozooids—which are normally around 30 feet long and use venom-spewing cells to deliver painful, neurotoxic stings. When a tentacle is detached from the rest of the colony, it might wash ashore somewhere or drift around for days on end until it decomposes. Be warned: Even a severed tentacle can sting you.

5. ON RARE OCCASIONS, STINGS CAN BE FATAL TO HUMANS.

The odds of being killed by a Portuguese Man O’ War are slim. But just because deaths are rare doesn't mean you should touch one: On February 11, 2018, 204 people in Hollywood, Florida were treated for stings, which can lead to red welts on the skin, muscle cramps, elevated heart rates, and vomiting.

Still, the creatures can kill: One unlucky victim suffered a full cardiovascular collapse and died after getting too close to a Man O’ War in eastern Florida back in 1987. More recently, a woman swimming off Sardinia was stung by one and died of what was believed to be anaphylactic shock.

6. SOME FISH LIVE IN THEM.

Given that tiny fish make up about 70 to 90 percent of the Man O’ War’s diet (it also eats shrimp and other crustaceans), Nomeus gronovii, a.k.a. the Portuguese Man O’ War Fish, is playing a dangerous game: It lives among the siphonophore's tentacles even though it's not immune to its stings, swimming nimbly between the stingers. Young fish eat planktons which wander under their hosts and, as they get older, will sometimes steal the Man O’ War’s prey—or nibble on its tentacles.

7. SEA SLUGS LIKE TO STEAL THEIR TOXINS.

The Man O’ War has a long list of enemies. Loggerhead sea turtles and the bizarre-looking ocean sunfish are thick-skinned enough to eat them. There are also “blue dragon” sea slugs, which not only devour the Man O’ War but actively harvest and appropriate its toxins. After storing Man O’ War stinging cells in their own skins, the blue dragons can use it as a predator deterrent.

8. MAN O’ WAR COME IN PRETTY COLORS.

A pink-tinted Portuguese Man O' War with blue tentacles in the surf at a beach.
iStock

Although it’s translucent, the float is usually tinted with blue, pink, and/or purple hues. Beaches along the American Gulf Coast raise purple flags in order to let visitors know when groups of Man O’ War (or other potentially deadly sea creatures) are at large.

9. EVERY COLONY HAS A SPECIFIC SEX.

The Man O' War's gonozooids have sacs that house ovaries or testes—so each colony can therefore be considered “male” or “female.” Though marine biologists aren’t completely sure how the Man O’ War procreates, one theory is that the gonozooids release eggs and sperm into the open ocean, which become fertilized when they cross paths with floating eggs or sperm from other Man O’ War colonies. This “broadcast spawning” method of reproduction is also used by many species of coral, fan worms, sea anemone, and jellyfish.

10. LOOK OUT FOR MAN O’ WAR LEGIONS.

The Man O’ War isn't always seen in isolation. Legions consisting of over 1000 colonies have been observed floating around together. Because they drift along on (somewhat) predictable winds and ocean currents, it’s possible to anticipate where and when a lot of the creatures will show up. For example, the Gulf Coast’s Man O’ War season arrives in the winter months.

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