Tuesday, October 30, 2012

Top Five Scariest Parasites

I enjoy the occasional horror movie, but it is always nice to know that those vampires or zombies or Stay-Puff Marshmallow men are fiction.  Their existence ends when the movie ends.  Nature is not so kind.  It has creatures that make The Exorcist look like Casper the Friendly Ghost.  And they COULD BE ANYWHERE!  Maybe there is a parasite behind you right now...

This Halloween, enjoy my top five most terrifying parasites of all time.

5. Cordyceps

If I was an ant, this would definitely be at number one.  Imagine you are living your life, minding your own business, when suddenly you get an irresistible urge to climb.  You know you shouldn't, you've heard what happens to other climbers, but you can't help it.  You climb, you take a breather, and A FUNGUS BURSTS OUT OF YOUR HEAD.  Any parasite that can moderate its host's behaviour is scary indeed.

4. Horsehair worms

Speaking of behaviour modification, have you ever seen a grasshopper try to swim?  Odds are it was committing suicide under the direct control of its internal parasite, the nematomorph, or horsehair worm.  Once in the water, the drowning grasshopper has to faces the further embarrassment of having a the very large parasitic worm emerge from its rear and swim away to complete its life cycle.  Give me a fungus to the head any day!

3. Whatever this is

This is not CGI - no less that Jerry Coyne posted this video on his blog, whyevolutionistrue.wordpress.com

2. Botfly

These little creatures are too disgusting for words.  Their larvae burrow into and feed off of the flesh of all sorts of living things - cows, sheep, humans. Fortunately for us, the only botflies in Canada infect squirrels.  So long as you stay in Canada you should be safe.  Just stay away from people who have recently been to South America.

The first video is pretty neat, showing how botflies that prey on cattle use an intermediate to get the eggs to the cow.  The second video involves humans, and is not for the faint of heart.  I myself couldn't finish it.  There is an entire subgenre of video on Youtube featuring botfly extractions.

1. Candiru

This is a great parasite to tell your kids about if they have a habit of peeing in the pool.  The candiru is a small catfish that normally feeds off of the blood of other fish.  It has spines behind its head that it uses to lodge itself under the gill slit, and its spends its days happily feeding.  It tracks its fish prey through their urine trail.  Occasionally they follow the wrong urine trail.  There is one medically documented case of a candiru entering the urethra of an adult male, lodging itself in with its spines, and gorging itself until it died.  For that interview, watch Rivers Monsters.  Below is a less traumatic but still terrifying video of humanity's only internal parasite that is also a vertebrate.

Happy Halloween!

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