I’ve been getting into a blog called Sentient Developments. Here’s a fascinating passage from an entry called Just say no to mind controlling parasites:

Then there’s Dicrocoelium dendriticum. It’s a virus that primarily infects sheep — but it has a rather convoluted way of going about its reproductive business. First, adult worms lay eggs in the bile ducts of the sheep and are excreted. These eggs are in turn ingested by various species of land snails and the eggs hatch in their digestive tracts. This hatching releases a compound that continues to change until it is released by the snail in the form of a slimeball. This slimeball is then eaten by ants. This eventually develops into metacercariae within the abdominal cavity of the ants.

And here’s where it gets interesting (not that it hasn’t been a riveting tale to this point): the ant’s behavior is in turn altered such that it is compelled to climb to the very top of a blade of grass where it waits to get eaten by sheep. The sheep eats the grass with the ant on it and subsequently becomes infected. The cycle is complete.

I think that may be even cooler than Giger’s xenomorph life cycle.

OK, no. But still cool. And it’s real.