Alien World of Parasites

- My other Tongue is a Sea Louse -

Cymothoa exigua, a Crustacean, is the only known parasite that effectively replaces a body organ. It makes its home in the mouth of a single species of fish, the spotted rosesnapper, where it feeds on blood until the tongue withers and dies. It attaches itself to the remaining stub, and can be used by the fish as a replacement tongue to manipulate food.

- Happy Couple -

A female blood fluke spends its life of constant intercourse lodged in a groove along the front of the canoe-shaped male. These tiny flatworms cause little harm themselves, but their thousands of spiny eggs trigger immune system reactions that can lead to tissue damage and internal bleeding. They inhabit the blood vessels serving the intestines.

- Sacculina: The Crab Puppeteer -

Sacculina, a type of barnacle, begins its life in the ocean as a free-swimming larva. When the female locates a crab, however, she actually discards most of her own body, leaving a gelatinous blob that enters the crab and begins to grow. It sprouts rootlike tendrils that spread through the crab like a fungus, even wrapping around its eyes. Eventually it forms a small hole on the crab's back, through which a male Sacculina can enter and permanently join the female. The crab stops growing and stops mating, devoting all of its energy into caring for the parasite's eggs as though they were its own. Male hosts are even altered by the parasite to behave like females and adapt their shape to carry eggs.

- Eyeball Lice -

Ommatokoita elongata is a soft, worm-like crustacean that spends its days anchored in the eyeball of the greenland shark, feeding on eye jelly. Parasitized sharks are blinded, but function normally and may in fact benefit from the parasite's presence, which appears to attract small fish.

- Tiny worm, big problem -

Wuchereria bancrofti is a microscopic nematode responsible for one of the world's strangest and most debilitating diseases: elephantiasis, characterized by extreme, incurable disfiguration and massive growth of the legs and genitalia. These worms inhabit the lymph nodes and ducts, resulting in blockage and swelling of tissues.

- Clam-pire -

Many species of fresh-water mussel begin life in a parasitic stage called a Glochidia. Some species are bloodsuckers, attaching to fish with an adhesive tendril and serrated, beak-like shell. Others are internal parasites, allowing themselves to be swallowed. Nearly all are species-specific, and will survive only by finding the correct host.

- Long, Strange Trip -

The life cycle of the lancet fluke (Dicrocoelium dendriticum) goes as follows: adults inhabit cows or other grazers, releasing eggs that are spread in manure. When swallowed by scavenging snails, the eggs hatch and the parasites are eventually coughed up by the snail in balls of slime, which are then consumed by ants. Late in the evening as the temperature drops,  infected ants experience an uncontrollable urge to wander from their colony, climb a blade of grass and attach to the tip by their jaws. The ants will remain in this position until accidentally eaten by a large, grazing mammal... beginning the cycle anew.

- Up and Away -

Cattle know better than to eat near their own manure as it may contain thousands of expelled parasites, but the lungworm has found a solution. When it detects sunlight, it climbs to the surface of the dungpile and searches for a type fungus that is also a parasite of cows. This fungus reacts to light by launching its spores, which the lungworm will hitch a ride on and hopefully land in fresh grass to be re-ingested.

- Nowhere to Hide -

There is at least one species of parasite (or stage in some parasite's life cycle) specially intended for almost every non-parasitic species on the planet, including a multitude of creatures that even parasitize parasites, such as mites that live beneath the scales of fleas. Some parasites are extremely particular...another mite lives only in the left ear of one species of moth. They do not infest both, or their home would be too easily caught by a bat.

- The Early Worm Catches the Bird -

Leucochloridium varidae is a parasitic worm of birds and snails with an ingenious and disturbing means of passing from one host to another. In the body of a snail, it sprouts several tubes that it sends into the snail's eye-tipped tentacles. These tubes change to brilliant color patterns, pulsate, and swell until the tentacles resemble a pair of fat, wriggling caterpillars. This acts as a tempting beacon for predatory birds, and prevents the snail from retreating into its shell. The snail's behavior also changes, crawling in the open instead of seeking shade. When a bird spots the colorful tentacles, it rips them off, contracts the parasite and will scatter eggs in its droppings to be eaten by more snails.

Parasitic Insects and Arachnids

- Alien Offspring -

Many kinds of wasps lay their eggs on the bodies of caterpillars. When the caterpillar pupates, the wasp larvae kill and consume it, using the caterpillar's cocoon as their own. In some species, the larvae even alter the caterpillar's behavior, postponing its pupal stage so that their host will grow larger and fatter than usual.

- Hopping Vampire -

The leap of an average flea is equivalent to a 100 pound man leaping 1,000 and enduring a g-force of 20,000 pounds with an acceleration greater than that of a space shuttle. Maggot-like flea larvae subsist on a diet of hair and dead skin from host mammals while adults suck blood. Mature fleas can survive many months without food, lying dormant in cocoons.

- Brain Eater -

The female phorid fly injects a single egg into the body of a fire ant. When the maggot hatches, it burrows into the ant's head to feed and grow. When ready to mature, it secretes an enzyme that causes the ants head to drop off. The decapitated head makes a perfect armored cocoon for the developing fly.

- Too Close for Comfort -

Female "chigoe" or "sticktight" fleas (also known as "jiggers") dig themselves into the flesh of their hosts. The female mates with a more mobile male through a tiny hole in the flesh and will swell to the size of a pea as her eggs develop. Once she has laid her eggs outside her fleshy chamber, she dies. Secondary infection can easily set in with the swollen corpse still lodged beneath the skin.

- Parasite Sister -

Strepsipteran ("twisted-wing") larvae parasitize the young of colonial bees and wasps, and mature into highly unusual dimorphic forms. The blind and limbless female remains in the same host for her entire life, her head protruding out through the host's body wall, while males metamorphose into winged adults with highly sophisticated and unusual eyes, similar to those of extinct trilobites. By sight and smell alone, a male finds a female poking out through a bee or wasp in, tackles the host and mates with the parasite through an orifice on her face. She will eventually give live birth through this same opening, depositing her spiny larvae on a flower to hitch a ride on other bees. When brought back to the hive, they locate developing bee larvae and drill into their bodies with a powerful acid. The bees will obliviously spend their lives with these alien siblings and continue to propogate them.

- Special Delivery -

The human botfly, too large and conspicuous to implant her own eggs, waits near her her intended human host until she spies a hungry female mosquito. She will catch the mosquito in mid-air, deposit her eggs on its underside and set it free. When the mosquito lands on a human for a drink, body heat causes the eggs to hatch and the tiny maggots make their way under the flesh. Each can grow as long as three inches, eating mucus and tissue in a hollow chamber just beneath the skin. They are rarely dangerous, but can cause considerable pain with their large, hook-lined bodies.

- Flesh Dissolver -

Chiggers, tiny relatives of ticks, are parasites only in their immature stage. Young chiggers niether bite nor drink blood, but attach tightly to the skin of their mammal hosts and secrete a digestive enzyme to liquify and suck of the surrounding flesh. The itchy, red rash associated with chiggers is an allergic reaction to this secretion. Adults are predatory.