Fungal Hunters
A class of carnivorous fungi lurks in the dirt. Will you be their next prey?
Fungi are commonly seen as static scenery, something with the same level of agency as a rock. But in some cases, this is a grave misconception. As proven by culturally familiar plants such as the Venus fly trap, the natural world is much more dynamic than we might think, often to the detriment of many members of the animal kingdom.
But the leap that many fail to make is that it is not just plants that hunt animals with such deceptive and surprising dynamism, it is also fungi! The landscape of fungal predators is both diverse and interesting, with over 200 species described so far and many more to come. Moreover, it’s thought that fungal carnivory has evolved multiple times in convergent evolution, with geneticists tracking a minimum of three separate lineages of fungal carnivores. Based on the relatively shallow depth of research into the fungal world as compared to the vegetative one, we should expect the true number of carnivorous fungi to be larger still.
One of the most common fungi that employ carnivory as part of their repertoire is the oyster mushroom. Oyster mushrooms, (pleurotus ostreatus) primarily feed by decomposing wood, but because wood is a nitrogen poor food, they turn to hunting nematode worms as a supplemental source of nitrogen. Nematodes are found in almost every soil environment around the world, and are one of the most common quarry for fungal hunters. In fact, nematodes are so common that if the entire earth except nematodes were to disappear, there would be a lightly visible web of nematodes enclosing the sphere where the the earth once was.
When starved of nitrogen, the oyster mushroom produces drops of poison on the tips of it’s hyphal roots. Once coming into contact with these poisonous droplets, the nematodes become paralyzed within two minutes. Then, the hyphae proceed to wrap around the nematodes, body, until their chemicals sensors detect that they’ve reached the worms mouth, at which point they burrow through the mouth, into the worm, and begin to digest it from the inside out. Gruesome!
Another fungal hunter, Arthrobotrys oligospora hunts nematode worms by cooperatively creating a 3 dimensional sticky net between multiple fungal nodes. This net releases pheromones that attract the nematodes, and once caught, it ensnares the worm in an elastic mess of sticky fungal tendons, which excrete poisons that paralyze the worm, similar in function but distinct in chemical makeup to that of the oyster mushroom.
Dactylella is my favorite fungus I’ll cover in this post, and is most notable for the amazing speed with which it pounces upon it’s prey. The dactylella fungal family creates nooses out of its hyphae, baited at the center with nematode attracting phermones, and upon the bait’s stimulation, the noose inflates in as little as 1/10th of a second, leading to the nematodes strangulation and eventual digestion by Dactylella.
That’s pretty terrifying. Being a nematode worm must be a terrifying existence. Still, it’s not like there aren’t unique dangers to being human, at least these little worms never have to come face to face with a gun right? Wrong! The specialized “gun cells” of the haptoglossa fungi are some of the most complex fungal cells known to science. The haptoglossa cell is a huge artillery cannon, lying in wait to fire a harpoon into the heart of passing nematodes and rotifers. Moby dick, indeed!
The last and perhaps scariest fungal hunter I’d like to showcase is Catenaria anguillulae. The spores of C. anguillulae are fast and motile, with flagellate tails that help to propel them through watery soil environments. Attached to each of these spores is a homing beacon that detects nematode pheromones and guides the spore to the mouth or alternative orifice of nearby nematodes. Then the spore latches on to the nematode. Nematodes are often beset by dozens to hundreds of these predator spores at once, reminiscent of a hulking mammoth being attacked by a hungry wolfpack. The prey seeking abilities of the C. anguillulae fungus may present an exciting opportunity for medical targeting.
I hope you enjoyed this run down of the world of carnivorous fungi! Let’s all hope that the battle that rages in the soil below our feet stays there, and doesn’t birth a new fungal threat like Cryptococcus Gattii (post here) anytime soon.
Until next time,
-Connor, OfAllTrades
Don’t forget to subscribe, it’s free!
And please share with your friends, family, and any other prospective readers you might know!
FOOTNOTE:
Shout-out to Merlin Sheldrake’s book, Entangled Life, which inspired me to write this post.
If you’d like to have more fungal fun, check out some of my previous posts on the subject:
To see more fungal hunters in action, check out these great videos:
As an aside, are you related to Alex Tabarrock, of GMU? If so, I think we played Diplomacy together once.
Wonderful overview! Fungi are creepy as hell, like a whole parallel world we don't know about, but works strangely similarly to ours in the macro sense, but entirely differently in the micro sense.