A Mushroom Grew in a Strange Place: The Side of a Frog

Over the summer, Lohit Y.T., a river and wetlands specialist at World Wildlife Fund-India, set off with his friends in the drizzly foothills of the Western Ghats in India. They had one goal: to see amphibians and reptiles.

“There were five of us, busy searching for the species and avoiding leeches,” Mr. Lohit said.

But their herpetology hunt turned into a fungus find.

Dozens of Rao’s intermediate golden-backed frogs were in a roadside pond. But the crew noticed something different about one of the frogs perched on a twig — a curious growth. Upon closer inspection, they realized it was a tiny mushroom erupting from the roughly thumb-size frog’s flank, like an itty-bitty fungal limb. In other words, a mushroom sprouting from a living frog.

Mr. Lohit and his friends published a note on their discovery in January in the journal Reptiles and Amphibians.

After Mr. Lohit posted pictures of the frog online, citizen scientists and mycologists chimed in to say that the fungal hitchhiker resembled a type of bonnet mushroom. Bonnet mushrooms, collectively called Mycena, typically live on decaying plant matter, like rotting wood. So, how did one end up sprouting from a frog?

Very few fungi make mushrooms. For a mushroom to grow, a fungal spore has to set up shop on a surface and produce mycelia. Mycelia are threadlike cells that absorb nutrients, not unlike a plant’s root. If the mycelia find enough nutrients, the fungus can produce a mushroom.