Monsters Inside Me : Ways Parasites Hijack Their Hosts : Animal Planet

5 Ways Parasites Hijack Their Hosts

By Robert Lamb, HowStuffWorks.com

HowStuffWorks

Crustaceans may have been doing it first, but humans are no slouches. Read all about pirates at HowStuffWorks.com.

3. CRAB HACKING

Barnacles are a common sight in the sea, frequently hitching rides on the hulls of oceangoing vessels. Fortunately, sailors don't have to worry about the unsightly crustaceans breaching the hull, crawling inside and taking control of the ship.

Unfortunately for crabs, however, the barnacle-like Sacculina carcini carries out just such a pirate attack as part of its life cycle. The tiny, female S. carcini larva floats around until it can attach itself to a host. Then the pulpy little parasite stabs a syringe-like appendage through one of the crab's vulnerable joints and injects itself into the crab's body like a booster shot of living jelly.

At this point, the parasite starts putting roots down. A few tendrils through the limbs, a few around the eyestalks and soon S. carcini is drinking crab juice straight from the source, all while the host continues to crawl about in its daily life, unknowingly eating for two.

The crab continues in this fashion until it either dies or a male S. carcini notices the alien, fleshy knob protruding through the bottom of its shell. Seeing this, the male injects itself through the knob and into the crab as well, where it proceeds to produce sperm. At this point, the parasites cut off all the crab's reproductive and regenerative activities. The host now lives only to eat, acting as a mobile love shack and maternity ward for its parasite masters. Since S. carcini's fleshy knob protrudes where a female crab's brood pouch would hang, the host even helps distribute the parasite's young by stroking out clouds of future crab hackers.

Count down 5 ways parasites hijack their hosts:

5. The Hitchhiking Parasite If a parasite is just along for the ride, it will devise devious ways to make its way back home.		4. I Wanna Be Your Tongue If food is a primary goal, why not just take out your host's tongue and plant yourself in its place?
3. Crab Hacking Sailors don't have to worry about barnacles breaching the hull, crawling inside and taking control. Crabs unfortunately do.		2. Suicide Worms Those "voices" in your head compelling you to drown yourself? Could be molecules planted by Nematomorph hairworms.
1. Parasite Protectors What could be more devious than being used as a food source for a parasite's larvae? How about being programmed to protect the little ones after they hatch.

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