SCOTT SIMON, HOST:
If you're out in a forest at night, you wouldn't be surprised to see the glimmer of fireflies. But you might be startled to look down and see the glow of fungi. Turns out that some mushrooms do gleam in the dark, and not just in Colorado. NPR's Nell Greenfieldboyce reports on one reason why.
NELL GREENFIELDBOYCE, BYLINE: Scientists have discovered about 70 glowing fungi. One of the most dramatic grows in the coconut forests of Brazil. Locals call it the coconut flower. It looks like a plain old mushroom until it gets dark, and then you see its eerie green glow. Hans Waldenmaier is part of a research team at the University of Sao Paulo. I caught up with him when he was doing field work on these mushrooms. He says at night their glow is easy to spot.
HANS WALDENMAIER: You just have to turn off your flashlight and the mushrooms stand out if they're there.
GREENFIELDBOYCE: He says when there's no moon.
WALDENMAIER: If you have your light off, these green mushrooms, you know, they're basically the only light source that you see inside the forest aside from fireflies.
GREENFIELDBOYCE: The question is why would a mushroom glow? Jay Dunlap is a molecular biologist at Dartmouth's Geisel School of Medicine. He says some researchers have argued that the glow was just an accidental byproduct of metabolism.
JAY DUNLAP: In other words, they don't intend to make light, it just sort of happens.
GREENFIELDBOYCE: New work from Dunlap's lab casts doubt on that idea. His group collaborated with those researchers in Brazil to study that green glowing mushroom and found that its light production is controlled by a biological clock.
DUNLAP: We found that the light was made mostly at night and not mostly during the day.
GREENFIELDBOYCE: That suggests it's deliberate. And one possible reason to light up the night is to attract insects. Waldenmaier and his colleagues in Brazil decided to test this possibility by making their own glowing mushrooms. They used an acrylic resin to make mushroom-shaped replicas that were the right size and shape. Inside some of these artificial mushrooms, they put a green LED that made them light up. Dunlap says the researchers coated all of these fake mushrooms with odorless glue.
DUNLAP: So then they just put the mushrooms out in the forest and asked who came and got stuck.
GREENFIELDBOYCE: It turns out that lots more insects got stuck on the fake mushrooms that were making light. The results appear in the journal Current Biology. The researchers say that in a dense forest there's not much winds to carry fungal spores away, so visiting ants, flies and beetles probably do the job instead. Nell Greenfieldboyce, NPR News.
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