By channelling nearly 90 percent of their blood into their body while sleeping, glass frog more than doubled their transparency.

Life 22 December 2022

Corryn Wetzel is a writer.

The glass frog can increase their transparency by storing most of their blood in their body. Understanding how the frog pool their blood without experiencing blood clot could lead to new insights into preventing blood clot in other animals.

The tropical, marshmallows-sized toads sleep on bright green leaves and look for food in the dark. Most animals need to continuously pump red blood cells throughout their body to deliver oxygen to their tissues, so being semi- see-through helps glass frog avoid being spotted by predators.

The American Museum of Natural History in New York states that transparency is rare for animals. The Fleischmann's glass frog is one of only a few species that have been able to do it. If it wasn't for the green skin on their back, you wouldn't be able to read a newspaper

The frog appeared translucent while sleeping compared to when it was awake, which led to a deeper investigation by the team. The researchers shined different wavelength of light on the animals while they were active and then rested. The frog becomes more transparent when it sleeps.

Transparent belly underside of male glassfrog (Hyalinobatrachium aureoguttatum), Canande River Reserve, Choco forest, Ecuador

The transparent belly of a male glass frog found in the Choco forest in Ecuador

A collection of GFCs.

When they traced the movement of blood in the living animals in real time, they found that glass frog can hide 89 percent of their red blood cells. The Frogs enlarged by an average of 40 percent. The frog's circulation increased and they became more opaque.

Karen Warkentin at Boston University was not involved in the work. It's pretty amazing to me.

Frogs don't seem to have negative health consequences from storing blood in their liver, even though packing red blood cells together leads to clotting. The hope is that the work can advance the treatment of blood clot in people.

The journal's title is Science.

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