Killer Fungi

As you sit down for dinner this Thanksgiving, take a moment to consider all the foods on your plate. With mashed potatoes, turkey, roasted vegetables, and pumpkin pie, it's easy to eat a well-balanced meal. But have you ever wondered how you'd find a well-balanced meal if you were an underground fungus?

We're all familiar with mushrooms (like the oyster mushrooms in the photo above), but mushrooms are nothing more than the visible fruiting bodies of underground fungal webs that can cover acres.

These sprawling fungal networks are the foundation of every terrestrial ecosystem on Earth, and one of their key roles is eating decaying plant tissues and then cycling these stored nutrients back into the soil. And because plants are built out of complex carbohydrates (like a loaf of bread), it means that fungi end up eating a lot of carbs and sugars.

Now think about what you know of nutrition. Can any organism survive on carbs and sugars alone? No, they can't. Every organism also needs proteins to grow and repair tissues, so how do fungi add protein to their carb-based diets?

It turns out that fungi are also fierce and aggressive predators that lure, hunt down, and kill a wide variety of soil microorganisms, including amoebas, rotifers, nematodes, and springtails.

This is no easy task because many of these soil microorganisms are powerful and fast-moving compared to fungal hyphae, but the range of hunting strategies used by fungi is nothing short of astonishing. Some fungi produce tangled mats of hyphae that trap passing animals, others produce sticky glues like flypaper, others shoot projectiles or slice with sword-like protrusions, others secrete toxins that stun their prey, others build nooses that throttle animals as they try to crawl through the open rings, and others produce spores that wait in the soil then stick to passing animals.

There are a staggering number of microorganisms in the soil. For example, there are about 100,000 springtails and one to ten million nematodes per square yard, and tens of thousands of amoebas per gram of soil. But even with these numbers, the hunting prowess of fungi wouldn't be effective if they didn't have other tools at their disposal.

What's fascinating about fungi is that they can "smell" organisms like nematodes, and then, in response, they build traps and start hunting. Fungi may also mimic food cues to lure their prey closer. But the result is always the same: as soon as their prey is stunned or captured, fungal hyphae grow into the food and consume it as a source of protein.

So are these strategies effective? Yes, they are! Not only do fungi secure a source of protein for themselves, they also secure protein for plants, their primary mycorrhizal partners. For example, in one study, researchers found that 25% of the nitrogen used by trees came from springtails killed by fungi!

The fact that fungi actively hunt down and kill their prey may seem like an obscure topic, but these fungi occur in all the world's soils from the tropics to Antarctica, and their fungal hunting techniques probably help nearly all of the world's plants grow. Now there's some food for thought!

[If you'd like to learn more, or see some videos, I've included a few links below.]

Thank you for following and supporting the Lukas Guides newsletter. I love sharing nature stories and photos with you, and it's only possible thanks to your paid subscriptions and generous donations. Thank you for your feedback, kind words, and for sharing the newsletter with friends and family.

Wishing everyone a Happy Thanksgiving!

More Resources:

This scientific paper provides an excellent overview of nematode-eating fungi. And this paper is another excellent overview, although it's a bit more technical.

This 9-minute documentary tells the story with high-quality footage.

There are also a handful of YouTube videos about nematodes and fungi. Here are three short videos: this one is the most comprehensive, this one is very short and just shows the noose technique, and this one is a bit gruesome and not for the faint of heart.