Overview
The Tarantula Cordyceps (Cordyceps ignota) is one of the most enigmatic, macabre, and fascinating entomopathogenic fungi inhabiting the tropical rainforests of the Neotropics. Belonging to the order Hypocreales, this specialized fungal parasitoid infects large terrestrial mygalomorph spiders—specifically theraphosid tarantulas—slowly replacing the host’s internal tissues with a fungal mycelial matrix before sprouting an extraordinary fertile fruiting body straight through the spider’s exoskeleton.
Biology and Physical Characteristics
Cordyceps ignota initiates infection when microscopic sexual ascospores or asexual conidia adhere to the cuticle of a hunting tarantula. The spores germinate, secreting specialized cocktails of chitinases, proteases, and lipases that dissolve the host’s armored exoskeleton. Once inside the hemolymph, the fungal mycelium proliferates as yeast-like blastospores, consuming non-vital organs while keeping the spider alive until it achieves complete tissue takeover. Following the spider’s death, the fungal hyphae mummify the host body into a rigid sclerotium. It then erupts through the joint membranes of the carapace or leg sockets, producing one or several elongate, wiry, pale ochre to burnt-cinnamon clavate stromata tipped with a bumpy, spore-bearing perithecial head.
Behavior and Ecology
Infecting subterranean, long-lived predators presents unique ecological challenges. Cordyceps ignota manipulates host behavior in subtle ways, occasionally compelling infected tarantulas to wander closer to burrow entrances or elevated mossy mounds where air currents facilitate spore dispersal. The mature fruiting stroma breaches the surface layer of forest litter, orienting its fertile apex toward open air. Here, microscopic flask-shaped perithecia forcefully discharge thousands of filiform ascospores into the humid understory breeze, maintaining natural equilibrium among apex arachnid populations on the forest floor.
Conservation and Human Impact
Due to its highly secretive nature and the subterranean habits of its tarantula hosts, Cordyceps ignota is categorized as Data Deficient on global biodiversity checklists. Encountering a specimen in the wild is exceedingly rare, celebrated by mycologists and tropical field biologists as a pinnacle discovery. Like many specialized tropical fungi, its survival hinges completely upon the preservation of mature, undisturbed primary rainforests with healthy populations of large burrowing mygalomorph spiders and stable microclimatic humidity regimes.
Interesting Factoid
This parasitic zombie fungus targets giant rainforest tarantulas: after completely mummifying the spider underground, it grows a bizarre, horn-like spore tower straight out of the spider’s head and upward through the forest soil into the air.
Last updated: October 2026