And IIRC, snail flukes do a similar thing: When they are ready to move from their snail host, they migrate into its eye stalks, which turn bright colors. The in

And IIRC, snail flukes do a similar thing: When they are ready to move from their snail host, they migrate into its eye stalks, which turn bright colors. The infected snail loses its fear of open spaces and climbs onto a branch or leaf, where a passing bird spots what looks like juicy worms and pecks off the stalks. The fluke is now in the bird's digestive system, and it starts manufacturing eggs. The eggs are embedded in the new host's guano, which falls to the ground. A passing snail eats the guano and becomes infected with flukes, starting the cycle anew. Update: http://www.youtube.com/watch?v=EWB_COSUXMw http://www.youtube.com/watch?v=EWB_COSUXMw Some varieties use three or more hosts. Dawkins describes one parasite that infects snails, birds, and sheep in turn.