Becoming Invisible: Glass Frogs Unveil Their Mystery to Scientists

Scientists were clueless about this almost supernatural ability of tropical glass frogs to become virtually transparent. However, new research techniques have shed some light on the puzzle.

Scientists may have solved one of nature's mysteries by showing that tropical glass frogs from Central and South America turn transparent by removing almost all of their red blood cells from circulation and placing them in the liver, new research in peer-reviewed Science has indicated.

At the same time, the amphibian evades the negative effect of blood clotting, leading to hopes that studying the unusual ability may advance human hematology.

"They [frogs] somehow pack most of the red blood cells in the liver, so they're removed from the blood plasma. They're still circulating plasma... but they do it somehow without triggering a massive clot," stated Jesse Delia, a researcher at the Museum of Natural History in New York.

Roughly 90% of the frogs' blood cells become packed together in the liver, almost doubling its size. After nightfall when the tiny thing decides to become active again for the sake of hunting and mating, it releases blood cells from the liver into circulation.

These creatues, which are barely 2.5 cm in length, spend most of their time on leaves in the Central and South American tropics where the ability to become transparent is perfect protection from predators.

"If you turn these frogs over, you could watch their heart beating by itself. You can see through the skin and see the muscle, the majority of the body cavity is really transparent," explained Delia.

Now, the puzzle is how these animals manage to avoid blood clotting during their manipulations; however applying that knowledge to help humans could take decades, scientists noted.