Buzz
Evolution is a ruthless, unpredictable force. It operates through random mutations and rewards only those who possess traits that enhance their chances of passing on their genes. This process can give rise to organisms with awe-inspiring features, but it can also result in parasitic creatures that are deceptively cunning.
Parasites are ubiquitous. Nearly every species on Earth has another that has evolved to invade or attach itself, feeding off its host's resources. While some parasites simply need to fly and bite their host, others follow incredibly intricate life cycles that involve multiple hosts to survive.
Here are 10 devious strategies employed by parasites to ensnare their hosts.
10. Mental Manipulation
Arguably the most well-known parasite today is the cordyceps fungus, which targets jungle ants and other insects. Its fame skyrocketed after featuring in HBO's The Last of Us, where it evolves to infect humans, turning them into vicious zombies. This portrayal brings attention to how parasites can exert control over their hosts' minds. The process is both eerie and sophisticated.
Ants typically remain close to the jungle floor, where their food sources are plentiful. However, this location doesn’t suit the fungus’s needs. The fungus must reach higher ground to capture another ant for its lifecycle. It manipulates the ant's brain with tiny growths and chemical signals, compelling it to climb up plants. Once the ant reaches a certain height, it bites into the vein on the underside of a leaf—a behavior known as the 'death bite.' This act ensures the ant stays anchored even after death.
At this point, the fungus is in prime position to thrive. After consuming the ant's nutrients, it bursts through the exoskeleton, sprouting a tall spike that releases spores. From its elevated perch, the spores fall to the ants below, ensuring the spread of the parasitic cycle to a new generation.
This form of parasitic mind control dates back at least 48 million years, as fossilized ants stuck in the death bite pose have been uncovered.
9. Encourage Sociability in Hosts
When we gaze at flamingos, we're often struck by their striking pink hue, but few realize what makes them so vividly colored. While some may point to their diet of pink shrimp, this explanation is only part of the story. The real culprit is parasites.
Many of us have fond memories of keeping sea monkeys as children. However, despite their playful image on the packaging, these 'monkeys' are actually tiny shrimp. These shrimp form a significant part of a flamingo's diet, contributing to the bird's vibrant pink coloration.
The reason sea monkeys develop such a striking pink color is because they are hosts to a tapeworm called Flamingolepis liguloides. These worms mature inside flamingos, but to reach that stage, they must first be consumed by the birds. To ensure this happens, the worms make the sea monkeys more noticeable by turning them red. Additionally, they encourage the shrimp to gather in large, sociable swarms, turning the sea monkeys into easy targets for the flamingos’ next meal.
8. Imitate Their Offspring
When a beautiful butterfly flutters past, parasitism is probably the last thing on your mind. Yet, the large blue butterfly, with its name as striking as its appearance, begins its life by tricking ants into raising it as one of their own.
The butterfly, Phengaris arion, has developed a remarkable strategy where its larvae closely resemble the young of myrmica ants. However, the deception runs much deeper. The larvae not only mimic the appearance but also emit the same scent as the ant larvae. Upon hatching, the butterfly larvae drop near an ant nest and wait for an unsuspecting ant to approach. Mistaking it for a lost ant larva, the ant carries it into the nest. There, the butterfly larvae are nurtured and cared for by the ants until they are ready to emerge.
Various butterflies within this family exhibit similar parasitic behaviors, each preferring a particular species of ant with which to be raised, based on the unique chemical substances they use to deceive the ants.
7. Transform Them into Fruit
When a parasite's life cycle depends on multiple hosts, it can be a challenge to transition between them. A common tactic used by many parasites is to get the first host consumed by the next, ensuring the parasite is carried directly to its next home. To facilitate this, parasites often alter their host's appearance.
The South American ant Cephalotes atratus might seem rather unremarkable at first glance. It has a simple black appearance, and its most interesting trait is its ability to glide through the air when it falls, using its legs to control its descent. Its dark, sturdy exoskeleton also makes it an unlikely target for birds. However, things take a drastic turn when the ant becomes infected with the parasitic nematode Myrmeconema neotropicum.
Upon infection, the parasite causes a significant change in the ant’s exoskeleton, thinning it out considerably. This renders the ant more vulnerable to predators, but it also alters its appearance by drawing red pigments to the surface of its body. As a result, the ant's abdomen takes on the look of a ripe red berry. Birds are then tricked into swooping down to consume the “berries,” thereby helping the parasite to reach its next host.
6. Luring Predators
Snails often lead unremarkable lives, slowly crawling along the ground, yet they can fall prey to a variety of parasitic invaders. One such parasite is the psychedelic Leucochloridium paradoxum, which manipulates its host in a dramatic fashion, ensuring its eventual consumption in a manner that is hard to ignore.
This parasitic fluke infiltrates the snail’s body and gradually spreads, consuming up to 20% of the host’s tissue. It then forms brood sacs that protrude into the snail’s eye stalks, pulsating with movement. These eye-catching, green-banded growths attract the attention of any birds nearby, signaling an easy meal. To increase the chances of the snail being eaten, the parasite also alters the snail’s behavior, making it more likely to stay in well-lit areas where predators can spot it more easily.
After a snail has been ingested, the parasite travels to the bird’s digestive system, where it starts laying eggs. These eggs eventually drop to the ground as a result of the bird's natural defecation process, waiting for a snail to crawl over them.
5. Mimicking a Mate
In the natural world, sometimes one gender of a species faces a particularly cruel fate. Take the male anglerfish, for example. This minuscule creature, many times smaller than the female, attaches itself to her skin and gradually dissolves its body, leaving only its reproductive organs to deliver sperm to the female.
In the world of insects, there exists a parasitic beetle that targets only males. The larvae of the blister beetle, Meloe franciscanus, employ a clever trick to infiltrate a bee hive. Upon hatching, they gather in a ball atop a plant and release a potent hormone that lures male digger beetles, tricking them into thinking a female is ready to mate. As the bee attempts to mate with the mass of writhing parasites, they latch onto the bee. Later, when the male bee finds a real mate, the larvae move to her and are carried to the hive.
Once in the hive, the larvae are cared for as if they were the bee's offspring, but they also consume the bee's young in the process.
4. Transform You Into a Different Orientation
Periodical cicadas boast a fascinating life cycle. Massive swarms of these insects emerge every 13 or 17 years to reproduce. After spending over 99% of their existence underground, developing, the cicadas have only a brief few weeks to ensure the survival of the next generation before dying. This makes the parasitic fungus Massospora cicadina even more merciless.
The spores of this fungus settle into the soil and infect cicadas as they make their way out of the ground to bask in the sunlight for their short-lived moment of adulthood. Once infected, the fungus overtakes the cicada's abdomen, causing it to appear as though the rear end of the insect is decaying, leaving behind a large white mass. This fungal growth disperses spores onto the ground and other cicadas nearby. Those affected have been described as 'flying salt-shakers of death.'
Male cicadas infected with the fungus begin to flick their wings, a behavior typically seen only in females. This behavior lures other males who then attempt to mate with the infected ones. Under normal circumstances, a male would repel another male attempting to mount, but when infected, they will tolerate the act. This behavior accelerates the fungus's spread.
3. Lampsilis Mussels
Mussels are commonly regarded as harmless filter feeders living in aquatic environments. The worst they could do is cause an upset stomach if consumed. However, if you’re a fish, they might use deceptive tactics to make you carry their offspring.
Lampsilis mussels, which inhabit freshwater, have developed clever tricks to entice fish. The sacs the females use to carry their young are designed to resemble the prey fish typically hunt. Each species mimics a different type of animal. Often, these sacs resemble small fish, complete with eye spots and tails, creating an incredibly convincing illusion. Once a fish gets too close, the mussel strikes and shoots its larvae into the fish’s face.
Now carrying the mussel larvae in its gills, the fish becomes the perfect host. The larvae attach to the gills and feed on the fish's blood. After several weeks of parasitism, the larvae are mature enough to detach and begin their new life as stationary bottom feeders.
2. Organ Replacement
While most parasites prefer to remain unnoticed by their hosts to avoid being expelled, Cymothoa exigua takes a much more overt approach in its parasitic strategy.
The larva of this parasitic louse enters the fish through its gills and makes its way to the fish’s mouth. There, it clamps onto the fish’s tongue and cuts off its blood supply. With no blood flow, the tongue begins to decay and eventually falls off. While this spells trouble for the fish, the louse offers a solution. It positions itself on the remaining tongue stub and essentially functions as a replacement for the missing organ.
Now securely located in the fish’s mouth, the cymothoa louse feeds on a portion of the fish's food and also enjoys the mucus the fish produces. With its hunger satisfied, the louse mates with the males living in the fish’s gill pouch and begins laying eggs.
1. Transform Fear into Desire
Around half of the human population harbors the parasite Toxoplasma gondii, but most will never even realize it. The parasite's goal is to find its way into a feline host, where it can reproduce efficiently. While many parasites are specific in choosing their hosts, toxoplasma is an opportunistic parasite, able to live in almost any warm-blooded animal. To return to its feline host, it employs some clever tricks.
Toxoplasma spores are found in cat feces, and when rodents scurry across the ground, they often unknowingly ingest them. As rodents are primary prey for cats, this is a promising start, but the parasite goes further by altering the rodents’ behavior to increase the chances of being eaten by a cat. Infected mice exhibit lower anxiety levels and become more exploratory, making them more vulnerable to predation. The effects on rats are even more pronounced. Normally, rats avoid the scent of cat urine, but when infected, they begin to show signs of attraction to it, leading them closer to areas where cats reside, thus increasing the likelihood of being eaten and allowing the toxoplasma to return to its preferred feline host.
Toxoplasma may be linked to certain human behavioral conditions. Some studies have suggested that infection with this parasite is associated with an increased risk of suicide, the development of schizophrenia, and slower reaction times.
