10 Body-Snatching Parasites

Hans Hillewaert, Wikimedia Commons // CC BY-SA 4.03
Hans Hillewaert, Wikimedia Commons // CC BY-SA 4.03

There are a lot of parasites out there. Some estimates suggest that as many as half of all the species on earth live inside—and feed off—other species. One new study published online (which hasn't been peer reviewed yet) argues that the parasitoid wasps might be the largest single group of animals—a title generally thought to be held by beetles.

Practically every species has its own set of parasites, and even parasites have parasites. In many cases, a parasite's host is little more than a habitat where it can eat and breed. But some parasites have gone a step further, evolving ways to manipulate their hosts in ways that give the parasite a better shot at growing up and spreading its young far and wide. Their methods can be as deliciously gross as the worst imaginings of horror movie screenwriters. Here are 10 examples to inspire new terrors of the silver screen.

1. JEWEL WASP // AUSTRALIA, PACIFIC ISLANDS


The jewel wasp Ampulex compressa is iridescently beautiful, but it's a nightmare for the American cockroach. When a pregnant female wasp gets hold of a roach, she temporarily paralyzes its muscles with a sting, then threads her stinger up into the roach's brain, injecting a cocktail of chemicals that turn the roach into a zombie. The roach could move when the paralysis wears off, but now it doesn't want to. Instead, it allows the wasp to gently lead it by one antenna to her burrow, where she walls it in with one of her eggs. That egg will soon become a larvae that spends its first week on earth eating the living roach bit by bit before pupating and emerging as a wasp to continue the cycle.

2. NEMATOMORPH HAIRWORM // EUROPE

Everything seems normal for weeks after a long-horned grasshopper has drunk water containing the microscopic larvae of the hairworm Spinochordodes tellinii, but that changes as soon as the worm grows big enough to start yearning for a mate. That's when it secretes chemicals that change its host's brain chemistry, making deep water seem enticing to the insect. The grasshopper suddenly has a suicidal urge to take a long hop off a short pier, and as it drowns, the worm—now as much as three times as long as the insect it lived in—squeezes out of its host and swims off to find a mate. Other hairworm species prefer praying mantises or spiders as hosts, but it's the same endgame for them all.

3. PARASITIC BARNACLE // MARINE COASTS

Sacculina carcini
John Aplessed, Wikimedia Commons // Public Domain

A female Sacculina carcini starts its life like any other barnacle—as a tiny planktonic baby floating free in the ocean. But unlike your average barnacle, when she drifts onto a crab she doesn't just settle down and become a warty bump riding on its shell. Instead, she burrows into the crab and grows until she infiltrates every crevice of the crab's body. This can take years, but eventually she's big enough to inflate her bulbous reproductive structures through the crab's abdomen so microscopic males of her species can fertilize her eggs. Once that happens, her crabby host stops molting and growing; all it does is eat and take care of its parasite. Her babies are incubated inside the crab's abdomen, and since part of her is inside the crab's brain by now, she also hijacks its egg-caring behaviors—even male crabs nurture them—to aerate and disperse thousands of her own future mind-controlling brood.

4. ICHNEUMOID WASP // NORTH AMERICA

ichneumoid wasp
MirandaKate, Flickr // CC BY-NC 2.0

A female ichneumoid wasp Campoletis sonorensis sneaking up on a grazing caterpillar isn't looking for a meal for herself—she's shopping for a nose-to-tail larder for her young. The wasp injects one or two fertilized eggs under the caterpillar's skin, and just for good measure, squirts in a virus that will keep the caterpillar's immune system from attacking the invaders. When she flies away, the caterpillar goes right back to eating, but it's a dead grub walking: In a few days, the wormlike wasp larvae hatch inside the caterpillar. They'll spend a couple of weeks munching away at its guts until they grow large enough to burst through its body wall. Then, they spin cocoons—often beside or on the dead body of their host—and pupate into another generation of chest-busting parasitoids (which, unlike most parasites, always kill their hosts).

5. GREEN-BANDED BROODSAC FLATWORM // EUROPE AND NORTH AMERICA

A land snail's eyestalks are normally a pretty drab affair, but that all changes if the snail licks up bird droppings infected with larvae from the flatworm Leucochloridium paradoxum. The baby worms move into the snail's digestive gland, forming an asexual colony that can eventually make up a quarter of the snail's mass. As the colony matures, it starts packing members into bright green, squirming brood sacs that writhe up into the snail's eyestalks, swelling them into fat approximations of wriggling caterpillars. If that's not enough to grab a hungry bird's attention, those pulsing, writhing brood sacs can also break through the snail's body wall and crawl off to mimic a juicy grub on their own.

6. PHRONIMA AMPHIPOD // DEEP OCEAN WORLDWIDE


Freshwater and Marine Image Bank, Wikimedia Commons // Public Domain

The deep-sea amphipod genus Phronima is a literal body-snatcher. This parasitoid captures gelatinous salps—jet-propelled, filter-feeding planktonic animals that are closely related to vertebrates—and hollows them out with jaws and claws, consuming the salp's brain, gills, stomach, and muscles, and scraping its inner walls smooth. The salp body—technically still living—becomes a barrel-shaped, ocean-going home that the amphipod can maneuver like a miniature submarine. It might eventually be a full house, too—female Phronima keep their young in the barrel and care for them until they've grown.

7. RIBEIROIAN TREMATODE FLATWORM // NORTH AMERICA

deformed pacific chorus frog infected with ribeiroia ondatrae parasite
Brett A. Goodman, Pieter T. J. Johnson, Wikimedia Commons // CC BY 2.5

The horror starts when larvae of the parasitic flatworm Ribeiroia ondatrae leave the snail they used as a nursery and burrow into the tail of a bullfrog tadpole. When the tadpole metamorphoses into an adult frog—a period of time that varies between species—the flatworms form cysts around its developing legs, disrupting their growth in ways that damage or double them. The crippled, flatworm-infested frog can't jump away from predatory birds like herons, which gobble them up. The flatworm then spreads to new waterways wherever the bird poops.

8. GALL WASP // WORLDWIDE

gall wasp eggs
Justin 0 of 0, Flickr // CC BY-NC 2.0

Not even plants are safe from parasitism. Females of Cynipidae, the family of gall wasps, lay their eggs inside leaves or under bark, and their larvae make the plant cells surrounding them grow faster than they would normally, effectively forcing the plant to grow them a house. Weird, nonleafy shapes rise up out of the plant, filled with juicy nutritious tissues that feed the wasp larvae and surrounded by tough woody walls that protect it until it becomes an adult (more than a year in some species) and chews its way out of its safe space.

9. ENTOMOPATHOGENIC FUNGUS // NORTH AMERICA

goldenrod beetle infected by mind-controlling E. lampyridarum fungus
Steinkraus et al. in Journal of Invertebrate Pathology, 2017

Goldenrod soldier beetles depend on the family of flowering plants commonly known as asters, which includes goldenrods and daisies. The beetles eat the plants' pollen and mate in their shade. But if a beetle gets infected with the fungus Eryniopsis lampyridarum, it climbs up an aster's stem, clenches the base of a flower with its mandibles, and dies. Within a day, the fungus forces the dead beetle's wings open to expose its spores, which rain down on the hapless beetles below.

10. OPECOELID TREMATODE FLATWORM // PACIFIC MARINE REEFS

Coral colony infected by trematode Podocotyloides stenometra
Alamy

The tiny polyps that build stony corals are usually an inconspicuous brown. But that changes whenever a polyp inadvertently grabs a young Podocotyloides stenometra flatworm for a meal. Somehow, the trematode worm doesn't get digested—instead, it invades the polyp's tentacles, swelling them and turning them bright pink. The color is a bright billboard advertising deliciousness to butterflyfish on the reef, who eat the flashy polyps and spread the worm to other corals across the reef.

15 Positively Reinforcing Facts About B.F. Skinner

Silly rabbit via Wikimedia Commons // CC BY 3.0
Silly rabbit via Wikimedia Commons // CC BY 3.0

Burrhus Frederic Skinner was one of the preeminent American psychologists of the 20th century. B.F. Skinner founded “radical behaviorism”—a twist on traditional behaviorism, a field of psychology that focused exclusively on observable human behavior. Thoughts, feelings, and perceptions were cast aside as unobservable.

B.F. Skinner dubbed his own method of observing behavior “operant conditioning,” which posited that behavior is determined solely by its consequences—either reinforcements or punishments. He also coined the term "positive reinforcement." 

To Skinner’s critics, the idea that these “principles of reinforcement,” as he called them, lead to easy “behavior modification” suggested that we do not have free will and are little more than automatons acting in response to stimuli. But his fans considered him visionary. Controversial to the end, B.F. Skinner was well known for his unconventional methods, unusual inventions, and utopian—some say dystopian—ideas about human society.

1. B.F. Skinner invented the "operant conditioning" or "Skinner" box.

Skinner believed that the best way to understand behavior is to look at the causes of an action and its consequences. He called this approach “operant conditioning.” Skinner began by studying rats interacting with an environment inside a box, where they were rewarded with a pellet of food for responding to a stimulus like light or sound with desired behavior. This simple experiment design would over the years take on dark metaphorical meaning: Any environment that had mechanisms in place to manipulate or control behavior could be called a "Skinner box." Recently, some have argued that social media is a sort of digital Skinner box: Likes, clicks, and shares are the pellet-like rewards we get for responding to our environment with certain behavior. Yes, we are the rats.

2. B.F. Skinner believed that all behavior was affected by one of three "operants."

Skinner proposed there were only three “operants” that had affected human behavior. Neutral operants were responses from the environment that had a benign effect on a behavior. Reinforcers were responses that increased the likelihood of a behavior’s repetition. And punishers decreased the likelihood of a behavior’s repetition. While he was correct that behavior can be modified via this system, it’s only one of many methods for doing so, and it failed to take into account how emotions, thoughts, and—as we learned eventually—the brain itself account for changes in behavior.

3. He's responsible for the term "positive reinforcement."

B.F. Skinner eventually moved on to studying pigeons in his Skinner box. The pigeons would peck at a disc to gain access to food at various intervals, and for completing certain tasks. From this Skinner concluded that some form of reinforcement was crucial in learning new behaviors. To his mind, positive reinforcement strengthens a behavior by providing a consequence an individual finds rewarding. He concluded that reinforced behavior tends to be repeated and strengthened.

4. Some critics felt "positive reinforcement" amounted to bribery.

Critics were dubious that Skinner's focus on behavior modification through positive reinforcement of desired behavior could actually change behavior for the long term, and that it was little more than temporary reward, like bribery, for a short-term behavioral change.

5. B.F. Skinner's idea of "negative reinforcement" isn't what you think.

Skinner believed negative reinforcement also helped to strengthen behavior; this doesn't mean exposing an animal or person to a negative stimulus, but rather removing an “unpleasant reinforcer.” The idea was that removing the negative stimulus would feel like a “reward” to the animal or person.

6. B.F. Skinner taught pigeons to play ping-pong.

As part of his research into positive reinforcement, he taught pigeons to play ping-pong as a first step in seeing how trainable they were. He ultimately wanted to teach them to guide bombs and missiles and even convinced the military to fund his research to that effect. He liked working with pigeons because they responded well to reinforcements and punishments, thus validating his theories. We know now that pigeons can be trained in a whole host of tasks, including distinguishing written words from nonsense and spotting cancer.

7. B.F. Skinner's first book, The Behavior of Organisms, broke new ground.

Published in 1938, Skinner’s debut book made the case that simple observation of cause and effect, reward and punishment, were as significant to understanding behavior as other “conceptual or neural processes.”

Skinner believed behavior was everything. Thoughts and feelings were just unreliable byproducts of behaviors, he argued—and therefore dismissed them. Many of his fellow psychologists disagreed. Regardless, Skinner’s theories contributed to a greater understanding of the relationship between stimuli and resulting behavior and may have even laid the groundwork for understanding the brain’s reward circuitry, which centers around the amygdala.

8. B.F. Skinner created the "baby tender."

Skinner was fond of inventions, and having children gave him a new outlet for his tendencies. He designed a special crib for his infant daughter called “the baby tender.” The clear box, with air holes, was heated so that the baby didn't need blankets. Unlike typical cribs, there were no slats in the sides, which he said prevented possible injury. Unsurprisingly, it did not catch on with the public.

9. B.F. Skinner also developed his own "teaching machine."


Silly rabbit via Wikimedia Commons // CC BY 3.0

You may have Skinner to thank for modern school workbooks and test-taking procedures. In 1954 Skinner visited his daughter’s classroom and found himself frustrated with the “inefficiencies” of the teaching procedures. His first "teaching machine"—a very basic program to improve teaching methods for spelling, math, and other school subjects—was little more than a fill-in-the-blank method on workbook or computer. It’s now considered a precursor to computer-assisted learning programs.

10. Skinner imaged an ideal society based on his theories of human behavior.

Skinner admired Henry David Thoreau’s famous book Walden, in which Thoreau writes about his retreat to the woods to get in greater contact with his inner nature. Skinner's "Ten Commandments" for a utopian world include: “(1) No way of life is inevitable. Examine your own closely. (2) If you do not like it, change it. (3) But do not try to change it through political action. Even if you succeed in gaining power, you will not likely be able to use it any more wisely than your predecessors. (4) Ask only to be left alone to solve your problems in your own way. (5) Simplify your needs. Learn how to be happy with fewer possessions.”

11. B.F. Skinner wrote a utopian novel, Walden Two.

Though inspired by Walden, Skinner also felt the book was too self-indulgent, so he wrote his own fictional follow-up with the 1948 novel Walden Two. The book proposed a type of utopian—some say dystopian—society that employed a system of behavior modification based on operant conditioning. This system of rewards and punishments would, Skinner proposed, make people into good citizens:

“We can achieve a sort of control under which the controlled, though they are following a code much more scrupulously than was ever the case under the old system, nevertheless feel free. They are doing what they want to do, not what they are forced to do. That's the source of the tremendous power of positive reinforcement—there's no restraint and no revolt. By careful cultural design, we control not the final behavior, but the inclination to behave—the motives, desires, the wishes.”

12. Some felt Skinner's ideas were reductionist ...

Critics, of which there were many, felt he reduced human behavior to a series of actions and reactions: that an individual human “mind” only existed in a social context, and that humans could be easily manipulated by external cues. He did not put much store in his critics. Even at age 83, just three years before he died, he told Daniel Goleman in a 1987 New York Times article, “I think cognitive psychology is a great hoax and a fraud, and that goes for brain science, too. They are nowhere near answering the important questions about behavior.”

13. ... and others were horrified by Walden Two.

Astronomer and colleague JK Jessup wrote, “Skinner's utopian vision could change the nature of Western civilization more disastrously than the nuclear physicists and biochemists combined.”

14. B.F. Skinner implied that humans had no free will or individual consciousness.

In the late 1960s and early '70s, Skinner wrote several works applying his behavioral theories to society, including Beyond Freedom and Dignity (1971). He drew fire for implying that humans had no free will or individual consciousness but could simply be controlled by reward and punishment. His critics shouldn't have been surprised: this was the very essence of his behaviorism. He, however, was unconcerned with criticism. His daughter Julie S. Vargas has written that “Skinner felt that by answering critics (a) you showed that their criticism affected you; and (b) you gave them attention, thus raising their reputation. So he left replies to others.”

15. He died convinced that the fate of humanity lay in applying his methods of behavioral science to society.

In 1990, he died of leukemia at age 86 after receiving a Lifetime Achievement Award from the American Psychological Association. Proud of his work, he was nonetheless concerned about the fate of humanity and worried “about daily life in Western culture, international conflict and peace, and why people were not acting to save the world.”

A New DNA Test Will Break Down Your Cat's Breed

Basepaws
Basepaws

Modern DNA testing kits can reveal a lot of information about you just by sending your spit off to a lab for analysis. As a result, it's easier than ever to learn about your personal ancestry and health risks. And now, the same goes for your cat, too.

Basepaws is now offering what it calls the "world's first DNA test for cats," which can tell you which breeds your beloved fur baby likely descended from, in addition to other information about their characteristics. The CatKit will reveal whether your little Simba is more similar to an American Shorthair, Abyssinian, or one of the other 30 breeds on record, as well as determining which of the "big cats" (think lions) your kitty has the most in common with.

Here's how it works: After receiving your kit in the mail, you will be asked to collect a DNA sample from your feline friend. The current kit includes adhesives for collecting cat hair, but Basepaws will soon roll out new kits that call for saliva samples instead. (This will provide a more consistent DNA sample, while also allowing staff to process more samples at once, according to a company spokesperson. It also will make it easier to collect samples from hairless cats like Sphinxes.)

A cat DNA test result
Basepaws

Once you collect the sample, just mail it in and wait eight to 12 weeks for your report. Basepaws uses sequencing machines to "read" your kitty's genetic code, comparing it to the sequences of other cats in its network. "More than 99 percent of your cat's genetic sequence will be similar to every other cat; it's the small differences that make your cat unique," Basepaws writes on its website.

In the future, Basepaws will also be able to determine your cat's predisposition for certain diseases, as well as their personality and physical traits. The company holds on to your cat's genetic data, allowing it to provide updates about your cat as the Basepaws database continues to grow.

Order a kit on the Basepaws website for $95. Enter the code "MEOWRCH-I5W3RH" at the checkout for a 10 percent discount.

And don't feel left out if you're a dog lover rather than a cat person—Wisdom Panel offers a similar service for canine companions. Its kit is available for $73 on Amazon.

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