According to recent findings, glass frogs, which are distinguished by their highly transparent muscles and undersides, carry out their "disappearing acts" by storing almost all of their red blood cells in their distinctively reflective livers.
The study, which was conducted by researchers at Duke University and the American Museum of Natural History, is being published in the journal Science on Friday.
The study may open up new directions in the study of blood clots, which frogs manage to avoid by storing and releasing about 90% of their red blood cells into their livers daily.
Glassfrogs achieve transparency by packed red blood cells into mirror-coated liver
The world's known glassfrog species number over 150, but we're only now beginning to understand some of the truly amazing ways they interact with their surroundings, according to co-lead author Jesse Delia, a Gerstner postdoctoral fellow in the Museum's Department of Herpetology, as per ScienceDaily.
Glassfrogs are nocturnal amphibians that spend their days sleeping upside down on transparent leaves that match the color of their backs, which is a common method of camouflage in the American tropics.
However, their stomachs reveal a startling feature: translucent skin and muscle that makes their bones and internal organs visible, earning the glass frog its common name.
According to recent studies, this adaptation conceals the frogs' outline on their leafy perches, making it more difficult for predators to spot them.
Animals that live in water frequently use transparency as a form of camouflage, but those that live on land rarely do.
Transparency is difficult to achieve in vertebrates because of the abundance of red blood cells that interact with light in their circulatory systems.
According to studies, ice fish and larval eels are transparent because they don't produce red blood cells or hemoglobin. The results of the new study show that glassfrogs, however, employ a different tactic.
The researchers at Duke University employed a method called photoacoustic imaging, which causes sound waves to originate from red blood cells.
As a result, scientists can map the location of the cells in sleeping frogs without the need for restraint, contrast materials, sacrifice, or surgical intervention.
This is crucial for this study because activity, stress, anesthesia, and death can all affect glassfrog transparency.
Hyalinobatrachium fleischmanni, a particular species of glassfrog, was the subject of the study's attention.
They discovered that when glassfrogs are at rest, their liver, which contains reflective guanine crystals, absorbs nearly 90% of their red blood cells, increasing transparency by two to three times.
Read more: Fighting the Frog Killer: Ending the Chytrid Fungus Crisis with More Fungus
Why glass frogs have see-through skin becomes clear
Tropical Central and South America is home to the glass frog, which gets its name from the color of its skin,as per The Guardian.
The frogs' skin on their backs is typically bright green, and their heart and intestines can be seen through their underbelly, but they are not truly transparent; rather, they are translucent. This has given rise to a query that has puzzled scientists.
Why do glass frogs have transparent skin at all rather than the opaque camouflage patterns of other tree frog species, if predators cannot see straight through the frogs? said Dr. James Barnett, a co-author of the study and a postdoctoral researcher at McMaster University in Canada.
According to Barnett and colleagues, the puzzle has been solved. The frog is always green to generally match the leaves, but the brightness of the leaves will vary, according to Barnett.
The team claims that while the legs are more translucent and therefore change in brightness, the body color of the frog does not change significantly against dark or light foliage, aiding in the amphibians' ability to blend in.
Barnett and colleagues describe how they conducted three experiments in their article for the American journal Proceedings of the National Academy of Sciences.
In the first, 55 glass frogs were photographed in two different settings-on leaves and against a white background-and the colors of the frogs in each were compared using computer models.
According to Barnett, "we found that the color of the frogs' bodies did not change much between backgrounds, but the legs did change significantly." The difference was due to a change in brightness rather than hue, she added.
The group then created computer-generated images of glass frogs against backgrounds of foliage that featured various patterns of translucency.
Twenty participants were asked to identify the frog as quickly as they could in 125 of these images.
When the frog was completely opaque compared to frogs with a natural pattern of translucency, the team found that participants were quicker to spot the frog.
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