May 25, 2009

Nasty Nature: Hair Worm Mindcontrol

When I wrote about zombie fire ants two weeks ago and mind-controlling fungus last week, I didn't plan to make "Nasty Nature" a semi-regular feature here on The Zed Word; however, I'm starting to learn way more than I ever knew about zombie behavior in the animal world as a result of parasitic organisms.

This week we take a break from ants, which seem common victims of parasitic mind control, and instead turn to the Hair Worm and it's suicidal power over the common grasshopper.

Nematomorpha (commonly known as hair worms or horse hair worms) are fascinatingly disgusting aquatic creatures that tend to shock onlookers when they are discovered living in their hosts. Hair worms are long, thin, and cylindrical, making them look similar to long strands of black, brown, yellow, or white hair. They range in size from 5–300 cm long and can be 0.5–10 mm thick. The parasitic portion of the hair worm's life cycle occurs after the eggs, laid in water, hatch. The hatched larvae swim to find a host, use their hooks to pierce the body, and then enter into the host organism. Hair worms that live in marine crustaceans belong to the class Nematomorpha whereas worms that live in terrestrial arthropods (like crickets, beetles, and cockroaches) belong to the class Gordius. Since hair worms are so thin, they can grow to surprisingly incredible lengths within the small body cavities of their hosts. When they emerge from the body to begin mating, the sight is often incredibly gruesome and unexpected as it erupts in a massive tangle of worm that significantly exceeds the size of the host. Check out this terrifying video of a hair worm emerging.

Bleck! Worse yet, some hair worms seem to create a form of mind control over their hosts that turn them into suicidal zombie slaves. In the case of Spinochordodes tellinii, which matures inside of grasshoppers and crickets, the worm seems to be able to force the grasshopper or cricket to commit suicide by drowning itself in order to return the worm to the water so it can complete the rest of its aquatic life-cycle.

Normally, grasshoppers will not leap into water -- that would be certain death -- but a team of French biologists who studied drowned grasshoppers in southern France discovered that the grasshoppers had been infected with hair worms, and the worms were some how able to hijack the grasshopper's central nervous system and compel the poor bugger to take the deadly plunge. Check out this video of the fatal mind-control in action!

For more examples and and explanation of the science behind this phenomena, click through to this video interview with Frédéric Thomas.

Thankfully for humans, we are not part of the life cycle and not compelled to drown ourselves if infested. Although some humans have been found with hair worms in their bodies because, like other animals (frogs for example), we might ingest animals infected with hair worms, the worms will not use us as part of their reproductive cycle or do us significant harm. I guess every worm-filled cloud has a silver lining.

But how long until something does evolve that might really turn humans into a form of water-seeking mind-controlled zombies? Has it already happened?

Do we honestly think anyone would participate in the insane Polar Bear swim without being mind controlled by a parasitic worm?

Come back next week for more nasty parasitic zombie nature when we take another look at ants and their ongoing persecution by zombie fungus.