Sunday, December 29, 2019

Oyster Gills

I'd just set out four trail cameras in a new area when I lucked into a small flush of Oyster Mushrooms on a decaying, but still standing, oak trunk. As I photographed their gills I was impressed by how fresh and debris-free they looked. (Click on any image to view it larger.)

But when I got the images home and viewed them on my monitor I cursed the stray strand of miscellaneous nature fragment that I hadn't noticed in the field.

I thought it was a superfine monofilament of lichen until I zoomed in and saw that it was a dewy strand of spider silk.

I also failed to notice the fungus crawlies. I'm going to guess this is a mite since it appears to have six legs and something like palps, but I poked around Google and Google Scholar a little bit without finding another picture like this guy. How does such a tiny creature ever find its way to the gills of a mushroom?!

Pleurotus ostreatus

One thing I learned as I was poking around for information on the crawlies is that oyster mushrooms don't just feed on wood. They also parasitize, i.e., eat, nematodes. To paraphrase The Big Lebowski: Sometimes the nematode eats the fungus. Sometimes the fungus eats the nematode. 

Although some fungi use constricting loops of hyphae to trap nematodes, and others use adhesive hyphae, the oyster mushroom poisons its prey. As we read here

"When grown in a nitrogen-poor environment like wood, P. ostreatus will produce a toxin on aerial hyphae. Instead of diffusing into the environment, the toxin remains as a droplet on the hyphae. In this manner, the toxin remains undetected by the unfortunate nematode until contact is made; the nematode is promptly paralyzed by the toxin. Hyphae will then colonize the nematode, and eventually digest it."

Interesting story about this in the New York Times (Jan. 2023)

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