A mushroom grew in a strange place: the side of a frog

Over the summer, Lohit YT, a river and wetlands specialist at World Wildlife Fund-India, headed with his friends to the drizzly foothills of India's Western Ghats. They had one goal: to see amphibians and reptiles.

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

But their herpetological hunt turned into a fungal discovery.

Dozens of Rao's middle goldenback frogs were in a roadside pond. But the crew noticed something else about one of the frogs sitting on a twig: a strange growth. Upon closer inspection, they realized it was a small mushroom erupting from the flank of the roughly thumb-sized frog, like a tiny fungal limb. In other words: a mushroom that sprouts from a living frog.

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

After Mr Lohit posted photos of the frog online, citizen scientists and mycologists said the fungus hitchhiker resembled a type of bonnet mushroom. Bonnet mushrooms, collectively called Mycena, typically feed on decaying plant material, such as rotting wood. So how did someone come from a frog?

There are very few fungi that produce mushrooms. For a mushroom to grow, a fungal spore must settle on a surface and produce mycelia. Mycelia are thread-like cells that absorb nutrients, similar to the root of a plant. If the mycelia finds enough nutrients, the fungus can produce a mushroom.

That adds to the puzzle of the fungi and the frog. Mycelia are found on the surface of the amphibian's skin or further inside the body, says Matthew Smith, a fungal biologist at the University of Florida who was not involved in the finding. But the team didn't collect the frog or the mushroom because they just wanted to observe. So it's impossible to say exactly what was going on, he said.

Scientists have discovered fungi in the past that grow in places where they normally shouldn't grow, but Dr. Smith had never heard of a mushroom growing on living animal tissue. “I was very surprised when I saw it,” he said.