Did you know that some mushrooms can glow in the dark? It’s true: At least 70 species of fungi, all of them gilled mushrooms from the order Agaricales and each from one of four evolutionary lineages, have some kind of bioluminescence or another. According to a study published in Current Biology, shrooms probably put on these evening light shows to attract insects that might carry their spores around.
The researchers were investigating whether fungal glow follows a set schedule. Their bioluminescence relies on chemical processes inside the mushrooms’ cells and is of course more visible at night. It presents itself in different parts of the mushroom — sometimes the thready mycelium that shoots through the dirt like a web of roots, sometimes the fruiting body of the mushroom itself, and sometimes the spores that float off on the wind.
But it turns out that in some species, the luminescence is actually timed around the evening so that the chemical reactions that produce glow aren’t wasted during the day. That suggests it’s not just a beautiful evolutionary fluke: If mushrooms budget their bioluminescence, it probably serves some greater purpose. And given how attractive these beaconlike glows are, it seems reasonable to start with the hypothesis that mushrooms are making a “come hither” gesture.
To test that, the researchers created fake mushrooms — baited with LED lights and rigged with sticky traps — and put them in the same Brazilian forest as the real mushrooms they were studying. They also put the same sticky fakes in without lights. As expected, many more insects ended up stuck to the glowing traps.
