Hallowain't, normally, focuses on something that sounds like it should be scary but turns out not to be. The case of the bluefin killifish, though, is slightly different in that the fate of the fish isn't supernatural, but is still pretty horrific.
The bluefin killifish, you see, is one of the creatures on Earth that gets turned into something akin to a zombie.
Killifish in California have been discovered to play host to a mind-sucking parasite that alters behaviour in order to further its own species. These zombie fish are infected with a fluke, a small, parastitic worm that reproduces in the guts of sea birds. The flukes are able to limit the production of serotonin in the fish’s brain, which makes the fish very restless. Ordinarily shy of the surface and its dangers, infected fish actively swim near and even flick the water surface, greatly enhancing the changes of getting plucked out and eaten by a bird.
If it's not bad enough having your mind controlled by a parasite, having your brain controlled by a parasite that really wants you to just get eaten already so it can infect a totally different species is awful. Like being forced to go on a terrible blind date, just so the person you're dating can chat up the bar staff.
Here's a video of the parasite under a microscope, appropriately 28 Days Later than the original infection:
And it's not just the poor bluefin killifish who ends up all zombie-like. Anand Varma has completed a photoproject, giving everyone a closer look at these souls being claimed:
At least actual zombies get to have a feast on a brain or two. The zombies of the animal world don't even get a decent meal out of it.
Hallowain't is OpenLearn's annual celebration of things that don't go bump in the night. In the run up to Halloween each year, we're the people going "there's a rational explanation."
Hallowain't was originally part of OpenLearnLive.