When people think of parasitic takeovers, they typically go to “The Last Of Us” as a basis for information from pop culture, and while it has its accuracies, there is a whole other domain of parasites too.Â
The green banded broodsac (or leucochloridium paradoxum, if you wanna get fancy) is a parasitic flatworm whose main hosts are land snails and birds. Now, you may be thinking, what do snails and birds have to do with each other? Well, the worms first infect the eye stalks of snails, which allows them full control to lure birds by acting like a caterpillar.
Once the bird eats the infected snail, the worm transfers to the bird, and proceeds to live in its cloaca and lay its eggs there for distribution through fecal matter. This is called “aggressive mimicry”, defined by the parasite resembling its main hosts (the bird) food, and imitating it (infecting a snail to fake being a caterpillar).
These parasites cause odd behaviours in snails, and yes, people were studying and watching the behaviour of snails. How painfully slow. Studies showed that the infected snails tended to stay in places with a higher luminosity longer, chose to sit on higher vegetation, and were significantly more mobile.
Infected snails live their lives normally, and can still reproduce, though sexual organs have been known to shrink when infected with this parasite. Snails typically live for about a year, and still have full use of their eyes even after they are taken over by the worm.Â
The worms were originally documented in Germany, but have been found and confirmed in Poland, Russia, Denmark, Sweden, Norway and a handful of other countries as well. There is a sole record of the parasite in the southern hemisphere, on Robinson Crusoe Island in the pacific. It is believed to be the same parasitic worm infecting slugs on that island as are infecting the snails in Europe.Â
The cycle of life will never cease to amaze me, even as weird little creatures like parasitic worms learn to take over snails to get to their main host’s body. Life always finds a way, and whether that is inherently good or bad, it is still something that is quite inspiring.