Glass frogs turn themselves transparent while sleeping on brightly colors foliage in the tropics to avoid predation. These frogs are able to pool their blood and create clots in their liver. This would be deadly in humans. The frogs are circulating only plasma. The mystery of how they do this has been solved, but the good news doesn't stop there. Scientists may also be able to use this information to better understand blood clotting in humans.
Read more on BBC: https://www.bbc.com/news/science-environment-64069630
Also on Science News: https://www.sciencenews.org/article/sleeping-glass-frogs-blood-liver