Glass Frogs: Transparent Skin, Blood-Storing Livers, and Unusual Heartbeat

Glass frogs hide their blood cells in their liver when they sleep
Glass frogs hide their blood cells in their liver when they sleep, Credit: Wikimedia/Geoff Gallice

Glass frogs are nocturnal animals with translucent skin. They also have a special ability to hide when they sleep. When they sleep, they transfer 90% of their blood cells into the liver. There are pockets in the liver where they store the red-colored cells and disguise them under a mirror-like surface present in the pockets. The heart also works unusually. Instead of blood, the heart pumps a bluish liquid. Circulation of the blood is curbed.


This has never been seen before in vertebrates and has left scientists in awe. This new way of camouflage increases the transparency of these frogs by almost two to three times. You may ask, if the frogs store blood cells in pockets, will the blood not clot? To the surprise of the researchers, the blood doesn’t clot. Further study could also help find a way to prevent blood clots in humans. There are other transparent animals found in nature as well, which are way more efficient than glass frogs. The Asian glass catfish, for example, is completely transparent.

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