June 14, 2009

Nasty Nature: The Liver Fluke Commands You!

In nasty nature, we look at zombie behaviour in the natural world where science fiction becomes science fact!

In our last installment of "Nasty Nature," we looked at the Hair Worm, a parasite capable of infesting grasshoppers and compelling them to commit suicide by drowning so the worm can be released back into an aquatic environment. Well, this is not the only worm in the animal kingdom capable of making its host a suicidal zombie slave.

There is also a species of Liver Fluke that find their way into the bodies of mammals through ants -- ants which they control! And the whole thing happens because snails, ants, and cows just want to get a bite to eat.

The adult liver flukes (Dicrocoelium dendriticum) live in the bodies of mammals like cows or sheep where they produce eggs that are passed out of the animal in its stool. Terrestrial snails come along, smelly a nice poopy dinner, and gobble up the stool that is infested with an unwanted worm egg salad.

Now the eggs begins the next stage of this bizarre life cycle. Inside the snail, the eggs hatch small larva known as miracidia. The miracidia multiply inside the snail's digestive glands, and are expelled from the snail's body in the slime the snail leaves in its wake. From here, ants appear. Just like the snails ate up the cattle's poop, so the ants want to make a meal out of the snail's slime. They collect it into balls, and take it back to the colony for supper.

Little do they know that this meal will be the death of them.

The larva in the slime has since developed into metacercaria, small spherical cases that contain an intermediary stage of the parasite. Inside their ant hosts, the metacercariae encyst in the ant’s body cavity. Eventually, one metacercaria takes root in the ant's nervous system and it is from here that the metacercaria robs the ant of its will.

For reasons still unknown to science, the metacercaria change the ant's behaviour to put them in harm's way. In the cool evenings and early mornings when grazing mammals are about, infected ants are forced by their zombie masters to crawl to the tops of flowers and grass. They stay there, stationary and fixed, until a lumbering mammal looking to satisfy a snack attack comes along and munches up all the vegetation.

The Vegetation infested with ants.

The Ants infested with liver fluke parasites that infect the mammal.

If the ants are lucky enough not to be eaten, they return to their normal behaviour when the day warms. But, the next night or evening when the day cools, they are again compelled to climb to their deaths under chemical command of their fluke worm masters.

This video from National Geographic illustrates the bizarre process.

What's scary about this is that biologists aren't exactly sure how the mind control works. I can totally see this premise working in a zombie movie. Imagine:

A company puts out a new ice cream flavor so delicious and so irresistible that people consume it like mad, especially on these hot summer days. Little do they know that the secret ingredient is the slime produced by a newly discovered exotic slug. For obvious reasons, the ice cream's producers keep this fact secret. Unfortunately, in that slime grow the eggs of a bizarre alien parasite that transforms all who eat it into undead monsters. Now, instead of ice cream, they want to eat you! I scream, you scream, we all scream for the DESSERT of the DEAD.

Copyright, Zedwordblog.com! It's mine! I call it. (Then again, the killer desert angle with zombies has already been done by The Stuff in '85. Shit.)