Glass frogs are native to the forests of Central and South America and get their name from their translucent skin and muscles that blend in with their jungle surroundings. When you turn these amphibians over, you'll see their hearts, livers and squiggly coils of intestines.
The scientists have now been able to discover why the amphibians turn transparent. The study was published in journal Science and is titled, 'Glassfrogs conceal blood in their liver to maintain transparency'. According to the study, these frogs can pool blood in their bodies without being affected by blood clots.
The glass frog, which is roughly the size of a marshmallow, spends its days dozing off on lush green leabes. The creature disguises itself on the leaf and increases its transparency to 61 percent in order to avoid being noticed by predators.
"At night, when the amphibians breed and feed, they're opaque. But during the day, when they snooze on leaves, most of their bodies, save for the lime green hue of their backs, turn transparent. This helps the frogs blend in like drops of dew, keeping them safe from spiders and snakes while they rest." the journal mentions.
This increased transparency appeared to be related to a decrease in the number of red blood cells coursing through their veins. Carlos Taboada, a biologist at Duke University and an author of the new study mentioned, "We could see that there was no blood there as the animals went to sleep. When they woke up, their blood started pumping again, reducing their transparency."
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The researchers used photoacoustic imaging, which maps the ultrasonic waves produced when red blood cells absorb light. They discovered that during the day, blood vessels in the frogs' livers were bursting with red blood cells, swelling the organ by about 40 percent . In comparison to other tree frogs, which can only store about 12 percent of their red blood cells in their livers, glass frogs can store an astounding 89 percent -nearly all of their red blood cells.
According to study co-author Jesse Delia, a biologist at the American Museum of Natural History, it is unclear how the animals survive this extreme adaptation. "Basically, they're not transporting very much oxygen for 12 hours a day," she says.
