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

5 Ways Parasites Hijack Their Hosts

By Robert Lamb, HowStuffWorks.com

HowStuffWorks

What compels some humans to kill themselves? Read all about suicide bombers at HowStuffWorks.com.

2. SUICIDE WORMS

What's that? You don't think the hosts in these examples are getting a fair deal? Just remember that we're not talking about symbiotic relationships, we're talking about full-blown parasitic infections. Sure, it may suck to be that hijacked crab or the ant with the swollen abdomen, but some hosts have a much shorter time of it.

Consider the plight of the grasshopper or cricket unlucky enough to sustain a bodily invasion from a Spinochordodes tellinii. These Nematomorph hairworms can grow to three or four times the length of their hosts, but when it comes time to burst out "Alien" style, they need to dive straight into some water to survive.

Rather than simply waiting around until its host enjoys a poolside siesta, the hairworm hacks into the insect's brain and compels it to seek out some water and drown itself. Obviously, the process involved in this particular hijacking is a bit more advanced than simply posing as a red snapper's tongue. The hairworms actually pump molecules into the host's brain that mimic its own proteins and produce the suicidal tendencies.

Scientists are still trying to understand the mechanics of this selective behavioral manipulation. The payoff, however, might prove rather noteworthy: a better understanding of the chemical reactions underlying human behavioral responses.

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.

CONTENT