The Anticlotting Ability of the Glass Frog

The tiny glass frog (genus Hyalinobatrachium), known for its translucent skin, is found in forests stretching from southern Mexico to northern South America. How does the frog’s skin become transparent? The glass frog moves most of its bright red blood cells into its liver—yet the blood does not clot!

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Consider: A team of researchers studying one species of glass froga found that it squeezes nearly 90 percent of its red blood cells into its liver, which is enclosed within a crystal-filled sac. While the frog sleeps, its liver enlarges by about 40 percent. The crystals act like tiny mirrors that reflect light and hide the liver, which contains the blood cells.

Crowding red blood cells so closely together would normally cause a life-threatening clot. Yet the glass frog does this without any apparent health problems. Interestingly, if the frog is injured, the blood will clot normally at the wound.

For decades, medical researchers have searched for better ways to prevent excessive clotting. They hope that understanding how glass frogs prevent their blood from clotting will lead to new treatments for humans.

What do you think? Did the glass frog’s ability to avoid blood clots evolve? Or was it designed?