American scientists have identified the physiological process allowing glass frogs to become almost transparent during their sleep, in order to deceive the vigilance of their predators.
A rare ability in vertebrates
Measuring on average 2 centimeters long, the glass frogs sleep during the day perched on bright green leaves, shelter that these tropical amphibians leave only under cover of darkness to feed. While their translucent skin helps them blend in effectively with their surroundings, it is a physiologically complex and constraining process.
« Transparency is generally rare in vertebrates, because most of them must constantly circulate red blood cells in their various tissues in order to oxygenate them. says Jesse Delia of the American Museum of Natural History. ” Only a few species of fish and amphibians are known to achieve such a feat, including Fleischmann’s glass frog. »
In the context of work published in the journal ScienceDelia and her colleagues measured the opacity of frogs when they slept and were awake, and discovered that the translucency of their skin increased by about 61% while they slept.
By following the blood circulation of different specimens in real time using photoacoustic imaging, the researchers discovered that the glass frogs could ” hide » about 90% of their red blood cells in their liver. Expanding on average by 40% during these phases of rest, it then regained its normal volume.
Potential implications for human medicine
If the heaping up of red blood cells leads to coagulation in most vertebrates, their storage in the liver of batrachians did not seem to have a negative impact on their health. According to Delia, highlighting the precise mechanisms at work could potentially improve the treatment of blood clots in humans.
« This is the first in a series of studies documenting the mechanisms of vertebrate transparency, and we hope it will stimulate biomedical work aimed at translating the extreme physiology of these frogs into new targets for health and safety. human medicine concludes the researcher.
