A previously unidentified species of see-through frog has come to light in Ecuador after sitting forgotten in a jar in a laboratory for 20 years, scientists say.
The tiny red heart of the hyalinobatrachium yaku, a species of "glass frog," is visible through the translucent skin of its underbelly.
Biologist Diego Cisneros of Quito's San Francisco University told AFP he found the frog, less than an inch in size, in the Amazon in 1998.
But he didn't manage to identify it until after he saw photographs on Facebook in 2015 by other scientists who had found similar specimens.
The discovery was finally published last month, after his specimen spent nearly two decades in a jar of preserving fluid in a laboratory at the university.
There are other species of see-through frog like it, but only in very few of them can the heart be seen beating.
"Barely 0.2 percent of the species of amphibians have a visible heart," a biologist at the university, Juan Manuel Guayasamin, told AFP.
Experts say its transparency may be an means of avoiding predators.
"The other possibility is that it is more energy-efficient to have a transparent belly, since it does not need to process the elements that produce bodily opacity," said Guayasamin.
Frogs in Ecuador are particularly at risk due to deforestation, construction, oil drilling and mining.
"This frog represents the importance of conserving water as a resource," since it depends on clean rivers to survive and reproduce, Cisneros said.
The frog's delicate, breathable skin makes it particularly sensitive to environmental changes, "which causes amphibians to become extinct very easily."
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