A National Geographic scientist explains the odd phenomenon, which is killing snails all over North America.
Carl Zimmer tells the tale of the parasitic worm which hijacks the snail’s brain and makes them go crazy. The parasite worm is called Leucochloridium paradoxum, also known as green-banded broodsac. It invades the snail and hijacks its brain system. As Zimmer explains, the parasite can be seen in the pulsing snail tentacles, since the tentacles are transparent. After the parasite takes over the snail’s brain, it makes it crawl up plants. Usually snails don’t do that and they stay out of the light, but in this case the Leucochloridium paradoxum is calling the shots.
Since the snail is out in the open, it becomes an easy prey for the hungry feathered birds in the trees’ heads. Birds don’t usually eat snails, but they are drawn by their curiosity towards the slimy, pulsing tentacles. After the bird eats the snail, the parasite continues to reproduce in the bird. The chain is never broken since the parasite can enter the body of the next snail through the birds’ droppings.