As we gear up for the rumored release of The Last of Us 2, it seems only fitting to revisit the real-life fungus that reduced us to a feral horde of shroom-heads in the original game: the Cordyceps fungus. Not all of the 400 (and counting) members of the genus are bad news – and they don’t infect humans – but some, the “entomopathogenic,” group, tend to get a bit murdery with insects.
While traipsing through the Amazon, entomologist and wildlife photographer Aaron Pomerantz came face-to-face with this bar-none killer, and the photos are unbelievable. “I had seen a lot of Cordyceps action on TV (like the BBC),” he says. “But I was so ecstatic when I found my first Cordyceps in real life. It was an ant with a mushroom bursting out of its head in Peru.”
The ant-infecting fungus doesn’t go for a quick death – after all, a parasite with a dead host doesn’t get very far. Instead, it feeds on the animal’s non-vital organs until it’s time to reproduce. Then, it manipulates the ant’s behavior by taking over its brain, using chemical signals to control the host body. The zombie ant will climb a nearby plant, attach itself near the top, and sit pretty while the fungus devours its brain, sprouts out of its head, and disperses its spores as widely as possible.
It’s an incredibly precise way to die: the ant always climbs to around 25 centimeters above the ground, a zone with just the right temperature and water content for the fungus to thrive.
“Insects have been around for millions of years and have a pretty solid set of immune genes to fight off viruses, bacteria, fungi, etc.,” says Pomerantz. “So it’s really impressive that these entomopathogenic fungi are somehow able to bypass that immune system and engulf their host. Also, there are still so many questions! At what point did this fungus become parasitic? When and how and why did it come to overtake arthropods?”
Because of their hosts’ incredible resistance to infection, many species of Cordyceps have evolved to infect a single species. Meaning, you won’t find the same fungal parasite on a type of moth, as you will on a spider or ant.
This doesn’t always happen, however. On occasion, the colony will share some of the deadly burden, licking their neighbors to remove the spores before the fungus can sprout and grow. This can dilute the infection to a level that the individual ant’s immune systems can handle. “But the fungus [also] mutates and evolves around certain host immune defenses,” says Pomerantz. “Also, there are probably many more species of cordyceps out there that we haven’t identified yet.”
A mutating killer fungus that explodes out of your brain – add that one to the list of things we couldn’t cope with. No matter how you slice it, insects and their kin are hardcore. The world is a deadly place when you’re bite-sized, and yet, creepy crawlies dominate our planet thanks to a slew of amazing adaptations. From Alex-Mack-style shapeshifting, to 62 mph spit, they’re the ultimate badasses of the animal kingdom. For more photos of Cordyceps in action, head to the gallery below.
Want more parasite-fueled suicide in your life? Check out one of our favorite TED Talks from science writer Ed Yong:
IMAGES: Aaron Pomeranz