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| Oyster mushroom (Pleurotus ostreatus) - Worm killer! |
The oyster mushroom above is one of our favorite edibles once you get past the fact that it eats worms. Mark Bower explains this below.
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Fungi can play various ecological roles in a wide variety of ecosystems. They decompose dead organic material, they have extensive mycorrhizal relationships with plants, and they can be parasitic on plants, animals and even each other. However, there is another role that is less well known, and somewhat surprising. Over 700 species of fungi have evolved the ability to capture, kill and digest nematodes, utilizing them as a supplemental nitrogen source. They have chosen their prey wisely, since nematodes are the most abundant animals on earth, accounting for 80% of all animal individuals.
They have devised various ways to kill their prey. Some species have sticky hyphae which adhere to the worm. The fungus then secretes chemicals to paralyze and kill the nematode. It then sends other hyphae into the nematode’s mouth and anus to digest it. Other fungi are more sophisticated. Some secrete chemicals which attract the nematodes, luring them to their deaths. Others have specialized structures on their hyphae, such as adhesive knobs, spiny balls and even little loops which lasso the poor critters.
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| Orbilia sp. |
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| Shaggy Mane (Coprinus comatus) |
It can get even more complicated! Nematodes are great consumers of bacteria. When attacked, some bacterial colonies secrete urea, which can trigger a fungus to activate its nematode-killing mechanisms, thus protecting the bacteria from predation.
Here are a couple of examples of nematophagous fungi in this area. Tiny 1-2 mm Orbilia species above are the most ubiquitous worm killers on the planet. They really don’t look that vicious!
At the other end of the lineup of suspects, the Shaggy Mane (Coprinus comatus), looks the part of an evil worm killer.
As a side note, nematodes do have their supporters. Here is Barbara Kipfer (Homo sapiens) capturing and killing oyster mushrooms in order to protect the local nematode population.
To watch fungi attacking nematodes with different strategies, watch this video.
The first 3 minutes shows the capture mechanisms.
There is more information on carnivorous fungi at this link.
