Nature’s Oddities Part 7: Cordyceps

Respect this fungus! Be thankful that God provided us with a highly robust immune system capable of fighting it. If we were arthropods, we would not be so fortunate.

Here is the fearsome, ingenious, and successful Cordyceps.

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Cordyceps is a genus within the family Ascomycota. Commonly known as ball-sac fungi, they produce their spores in a distinctive sporangium called an ascus (“wineskin” in Greek) that the Cordyceps exploits in the fullest for its diabolical deeds. Other ascomycota, some of the most successful organisms on the planet, include the more friendly (and delicious) yeasts, morels, truffles and Penicillium (used to make cheeses and the antibiotic Penicillin). In fact, I had the distinct privilege to have found an ascomycete last weekend, mistaking it for a Gall Wasp’s abode.

So, how did Cordyceps, the relative of such common relatives make it into Anthony’s cannon of odd creatures? Well, there are a few reasons. For one, Cordyceps is highly infections—more virulent than many other bacteria and viruses. It is so effective that it can wipe out entire colonies of insects. Another reason is its extremely odd and clever behavior.

The genus Cordyceps has hundreds of species and each one parasitizes a particular animal species. This, in itself, is not too impressive. What makes it impressive is how it exploits its victims and its own physiology so ideally. Take the Cordyceps that infects bullet ants (P. clavata), featured in this movie by Sir David Attenborough.



The Cordyceps lands on the ant’s body, and enters throng the ant’s tracheae (breating holes). The innate immune capabilities of the ant are mostly directed towards prokaryotic organisms, like bacteria. They are ill equipped to combat eukaryotic organisms , like Cordyceps. Then the Cordyceps extends its mycelium (the fungal analog to roots) into the ant’s body tissues, absorbing nutrients to fuel its enormous fruiting body. Eventually the ant’s body succumbs to this invasion, but not before the Cordyceps altars its mind in a most beneficial manner. This is why the Cordyceps gets the prize.

Most fungi and plants have quite a bit of trouble distributing their offspring and achieving genetic diversity, since they cannot move. Angiosperms (flowering plants) are experts at manipulating animals, like bees, to spread their pollen around in order to achieve genetic diversity, and they are also experts at tricking animals like birds into distributing their seeds. They hijack animal’s mobility quite ably, but at considerable cost. They must expend enormous amounts of energy and nutrients making pretty flowers, delicious nectar, and nutrient-packed seeds to coax the animals into their plan. The Cordyceps is far more ruthless.

The Cordyceps, after infecting its host’s body, causes behavior changes that direct it to climb upwards. In the jungles, where Cordyceps are most common, this is very important, since the foliage is so dense and choking. Once the ant has climbed to considerable heights, it succumbs to the Cordyceps and dies, securely clamping onto a branch with its mandibles (a behavior ants don’t normally engage in). The Cordyceps then goes on to use every bit of the ant’s body tissues to build an enormous fruiting body that extends from the back of the ants head. In this fruiting body are thousands of spores packed with the characteristic ascus. The Cordyceps ascus is modified in a way to allow it to eject its spores as far away from the fruiting body as possible, so when the fruiting body erupts, at a place high in the trees, the spores are spread far and wide, covering vast distances.

Ants, always clever, have mounted an effective response to the Cordyceps. Ants are very attenuated to each others' behavior, and when one sister sees her sister acting in a way consistent with Cordyceps infection, she takes her sister off, far away from the colony, often at the cost of her own life. “For the greater good” is SOP for ants. Some species, like the infamous fire ant, s. invicta, bury their sisters alive.