Glassfrogs: masters of camouflage
These small frogs measuring between 20 and 30 mm live in the tropical forests of South and Central America. They use a particular form of camouflage, called transparency. As the name suggests, these amphibians are able to be completely invisible to potential predators by making their bellies completely translucent, a phenomenon never seen in any other vertebrate species to date.
The biggest challenge for these animals is to hide their red blood cells because their color might betray their presence ... A study recently published in Science studied a particular species of glassfrog, Hyalinobatrachium fleischmanni, and showed that during their sleep, these frogs store 89% of their red blood cells in their liver and thus become 34 to 61% more transparent. During this period, they maintain a normal circulation of their plasma, and the red blood cells are redistributed throughout their body in a few seconds when they wake up.
Knowing that red blood cells are responsible for the distribution of oxygen to the body, how can these frogs survive in this state for up to 12 hours a day without blood clots, with so many red blood cells in such a small space? These questions are still unanswered, but could have clinical applications in the treatment of thrombosis in humans...