A Fungus That Turns Spiders Into Zombies Is a Discovery to Haunt Your Nightmares

An abandoned gunpowder storage shed pokes out from a small mound of earth in what’s now a nature preserve in Northern Ireland. It is the perfect place for a spider: semi-subterranean, cool and dark. But in 2021, a crew working on a BBC nature program found more than an average arachnid lurking there. They spotted a dead spider with a lacy white fungus erupting from its body.

The fungus, scientists announced in a paper published last month in the journal Fungal Systematics and Evolution, is a newly discovered species that spreads its spore by hijacking a spider and turning the unlucky arachnid into a zombie. This evolutionary strategy has been made famous by the zombie ant fungus Ophiocordyceps, which inspired the video game and HBO show “The Last of Us.” This spider version is only distantly related to that fungus.

Volunteers at the Castle Espie Wetland Centre near Belfast were assisting the BBC filmmakers when they noticed the infected spider. Pictures of the specimen made their way to Harry Evans, an emeritus fellow at CAB International, a nonprofit organization focusing on agricultural and environmental research. “I posited that it was an unknown or unusual species and requested the specimen once the filming had finished,” Dr. Evans, an author of the paper, said.

When the BBC program aired, Tim Fogg, a cave explorer, reached out to Dr. Evans to say that he had observed a similar fungus in Irish caves. Each of the five infected spiders Mr. Fogg collected was engulfed by a tiny, tangled thicket of fungi.

João Araújo, an author of the paper and a curator of mycology at the Denmark Natural History Museum, said he and his colleagues believe that when a spore lands on a spider, the fungus sprouts a root-like structure called a germ tube that drills into the arachnid’s exoskeleton. Once inside, the fungus buds and multiplies, Dr. Araújo said, “taking over basically almost the entire body of the spider.”