The frog with see-through skin you can watch its heart beat through
This frog has see-through skin — you can literally watch its heart beat through its body.
Which one is REALLY true about the Glass Frog?
The short version
The glass frog has a translucent belly, so you can see its heart, liver, and intestines working inside. The transparency blurs its outline against a leaf so predators below can't spot it, and when it sleeps it hides almost all its red blood in its liver to become even more invisible.
Why it's so weird
- ✓The Glass Frog has skin, so you can watch its heart beat through its body.
- ✓The Glass Frog hides almost all of its red blood inside its liver while it sleeps to turn even more invisible.
- ✓The Glass Frog has a translucent belly that reveals its heart, liver, stomach, and intestines working inside.
- ✓The Glass Frog blurs its outline against a bright green leaf because light passes straight through its body, so below can't spot it.
- ✓The Glass Frog is now inspiring medical research into preventing dangerous blood clots in people.
You could line up about 41 of them along a 7-year-old!
The full story
This frog has see-through skin — you can literally watch its heart beat through its body. Meet the glass frog, one of the strangest animals in the entire rainforest. Flip it over and its belly is almost completely transparent. You can see its heart pumping, its liver, its stomach, even its intestines, all quietly working away inside. But the transparency is not just for show. Sitting on a bright green leaf, light passes straight through its body and blurs its outline, so predators looking up from below simply cannot spot it. And here is the really wild part. When a glass frog falls asleep, it hides almost all of its red blood inside its liver, turning itself even more invisible, then pumps it back out when it wakes. Scientists are now studying that trick to help prevent dangerous blood clots in people. Follow for more weird animal facts.
A glass frog looks see-through because of what its blood is doing. Red blood cells soak up green light and shine back red, so flowing blood is the easiest part of the frog to spot against a green leaf. When the frog sleeps, it pulls almost 90% of those red cells out of its blood and tucks them into its liver, which is lined with tiny mirror-like crystals that hide their color. With the red cells stashed away, light passes through the frog's muscles and skin instead of bouncing off, so its outline blurs into the leaf and predators looking up from below can't tell where the frog ends and the leaf begins.
📚 Source: Glassfrogs Hide Red Blood Cells in Their Liver to Become Transparent — Duke Pratt School of Engineering ↗In a 2022 study in the journal Science, scientists used photoacoustic imaging — a safe laser that makes red blood cells give off tiny sound waves — to map exactly where the blood went inside live, sleeping northern glass frogs (Hyalinobatrachium fleischmanni) and saw nearly 90% of it move into the liver, then return when the frog woke up.
📚 Source: Glassfrogs conceal blood in their liver to maintain transparency — Science ↗Watch the 45-second version
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“The Glass Frog has see-through skin, so you can watch its heart beat through its body.”
“The Glass Frog is a rare, pink, deep-sea predator often called a living fossil.”
“The Glass Frog hides almost all of its red blood inside its liver while it sleeps to turn even more invisible.”