Eerie 'zombie' spiders found roaming around Irish castle ruins

Scientists have found a fungus that creates spider zombies after they accidentally stumbled upon it in a Victorian gunpowder store on the grounds of a destroyed Irish castle. 

A new study explains that the fluffy white fungus likely uses chemical signals to direct cave spiders out of their lairs and into the open. The fungus then kills the spiders and uses the corpses to release its spores, according to Live Science. 

The never-before-seen fungus was first discovered by members of BBC's nature documentary TV series Winterwatch in a gunpowder storeroom at Castle Espie wetland reserve on Northern Island in 2021. 

The fungus was analysed by scientists and they discovered that the fungus is new to science and named it Gibellula attenboroughii to honour Sir David Attenborough in the journal Fungal Systematics and Evolution.

The Gibellula attenboroughii in the gunpowder store was on a dead orb-weaving cave spider, the Metellina merianae. These spiders usually inhabit the caves but will also inhabit dark human-made areas that are deserted such as cellars and cold storerooms. 

Tim Fogg, a caving specialist and study co-author found more examples of the fungus in cave systems in Northern Ireland and the Republic of Ireland. He also found the fungus on another cave spider species, Meta Minardi. 

Cave spiders usually prefer to stay concealed in lairs or webs but all of the infected insects were exposed on the roofs and walls of the caves in which they were found. 

The researchers believe that the white fungus altered the spiders' behaviour, sending them out into the open as well as exposing them to air currents that dispersed G attenboroughii spores. 

Study lead author Harry Evans told Live Science that the process of the fungus infection is complex and it would have evolved and become what it is today alongside the cave spiders. 

Evans explained that the fungus spores penetrate the spider and infect a cavity that holds the invertebrate version of blood, called the hemocoel. 

After the spider leaves its lair, G attenboroughii produces a toxin to kill its host and then uses antibiotics, an antimicrobial substance that kills the bacteria, so that the corpse can be preserved while the fungus mummifies it. 

The fungus absorbs all of the nutrients of the spider and when conditions are right, like high humidity in the cave, G attenboroughii grows long structures on the spider to disperse its pores.