Creepy, Eerie, Macabre Fungi for Halloween

Jan Thornhill

(This is a repost of the October 2013 one that somehow disappeared.)

Picture this: You’re in an unfamiliar part of the woods, alone. It’s spooky and dark. A storm is brewing. You hear something, stop dead in your tracks. Was it a howling wolf? Or just the wind? You’re alert now, all your senses are alive. And then you get a whiff of something—something so awful it makes your nose curl: the stench of rotting flesh, a nearby corpse. But where is it?

And then you see something…but it's not a corpse, though it's almost as grotesque. What you’ve found is a stinkhorn.

Two stinkhorns—Phallus ravenelii, with feasting slugs,
and Clathrus archeri (photos: Jan Thornhill; Wikipedia)

Stinkhorns are one of the more wondrous fruits of the fungi kingdom. They come in a bizarre variety of shapes, ranging from cage-like structures to tentacled stars that look like space aliens to rude-looking columns, some of which are dressed in lacy hoop skirts. Whatever their form, they all erupt—sometimes overnight—from an “egg,” and they all, at some point in their development, are covered in gross-smelling slime.

More traditional fungi rely on air currents to disperse their minute spores. Not the stinkhorn. A stinkhorn’s spores are imbedded in its stinky slime, disgusting muck that so closely mimics the smell of a decomposing cadaver it quickly attracts flies and other insects. When these insects take off again, they unwittingly carry away the stinkhorn’s spores stuck to their mouth parts and their tiny insect feet, spreading them far and wide. 

Stinkhorns are not the only macabre fungi you can come across in the woods. Walk farther and you might stumble upon some aptly named “Dead Man’s Fingers.” 

Dead Man's Fingers—Xylaria polymorpha (photo: Ulrike Kullik)

Properly called Xylaria polymorpha, these fungi are hardwood decomposers. They’re most often found on rotting logs, but when they grow from buried wood they can eerily resemble the blackened fingers of a corpse struggling to dig its way out from a forest grave. Unlike stinkhorns, which can pop up and then deteriorate in a couple of days, Dead Man’s Fingers are so horny and tough they can persist for months, or even years. 

And then there’s the Bleeding Tooth fungus.  

The spores of the Bleeding Tooth Fungus, Hydnellum peckii, are produced
on tooth-like projections beneath the cap. (photo: Darvin DeShazer)

The first time I stumbled upon one of these, it was so covered in “blood” I thought I’d found something recently killed. Though Hydnellum peckii, when fresh and moist, exudes something that looks shockingly like what oozes out of a slaughtered animal’s veins, the globules of pigment-filled liquid are nothing like animal blood. There is, however, a compound in these fungi that can affect blood. This compound, called atromentin, has anticoagulant properties similar to those of heparin, a medication used to prevent blood clots. Ominously, though, an overdose of these anticoagulants can cause a patient to bleed to death.

Some Omphalotus species, or Jack-O'-Lantern mushrooms,
glow in the dark. (photos: Thomas Schoch; Noah Siegel)

The fungi world provides even more Halloween-appropriate characters. In daylight, some of these look like perfectly normal mushrooms. But if you happen to be out for a midnight woodland stroll without a flashlight, you might be frightened by an eerie glow emanating from the base of tree—a glow produced by bioluminescent fungi. Scientists don't yet know why more than 70 species glow in the dark, but one idea is that their light might attract nocturnal insects that could help spread the mushrooms' spores. 

But the prize for the most frightening, the most macabre, the most fiendishly devious fungi has to go to the Zombie Ant Ophiocordyceps. 

The fruiting body of a Zombie Ant Ophiocordyceps protruding
from the head of a dead ant. The white nodules are another
parasitic fungus—a parasite of a parasite! (photo: David Hughes)

The Cordyceps family of fungi are parasites, and their chosen victims are often insects. But what makes Ophiocordyceps so unforgettable, and so nasty, is that after it has worked its way inside an ant's body, it travels to its brain, where chemicals are released that control the ant's actions. The now "zombified" ant is compelled to walk a distance from its colony, and eventually latches tightly onto a leaf with its mandibles. It will never let go. The fungus continues to grow, killing the ant and producing a fruiting structure that sprouts straight up out of the insect's head. The fungus then produces spores that are dispersed by air currents, so the fiendish cycle of Zombie Ants can continue. But, wait! There's some comeuppance for the dastardly Omphiocordyceps: a completely different parasitic fungi preys on it, reducing its ability to produce mature spores!    

For more information about fungi in general: http://www.mushroomexpert.com/

For more information about Zombie Ant Fungi: http://ento.psu.edu/directory/dhughes