Sleeping glass frogs disguise by storing most of their blood of their liver

When little glass frogs fall asleep during the day, nearly 90 percent of their red blood cells stop circulating.

Colorful cells crowd into hidden pockets inside frog livers that hide behind a mirror-like surface, a new study finds.biologists already know glass frog Possessing translucent skin but temporarily hiding bold red blood brings a new twist to vertebrate camouflage (Serial Number: 6/23/17).

“The heart stops pumping the normal red color of blood and just pumps blue fluid,” said Carlos Taboada, an evolutionary biochemist at Duke University and one of the discoverers of hidden blood.

Even more surprising to humans—prone to circulatory sludge and clogging—the frog clumped nearly all of its red blood cells for hours without clots, says Jesse Delia, now co-discoverer at the American Museum of Natural History in New York City. . Wake the frog up, and the cells decompress themselves and cycle again.

hiding those red blood cells can Double or triple the transparency of the glass frogTaboada, Delia, and colleagues report on 23 December scienceThis green transparency is very important to the snack-sized frogs, which spend their days hiding like tiny shadows under leaves high in the forest canopy.

What makes Delia wonder about transparency is the photo emergency. He has studied the behavior of glass frogs, but has never seen them fall asleep. “They go to bed, I go to bed — that’s been my life for years,” he said. However, when he needs some glamorous portraits, he puts some frogs in lab dishes and finally sees how the animals go about their day.

“Obviously, I couldn’t see any red blood in my circulation,” Delia said. “I took a video – it was crazy.”

When he pitched his project to a lab at Duke University for support, he was surprised to find that another young researcher was pitching the same lab to study transparency in glass frogs. “I was like, oh man,” Delia said. But Sönke Johnsen, who heads Duke University’s Biooptics Laboratory, told Delia and his competitor, Taboada, that their skills are different and that they should tackle the problem together. “I think we were level-headed at first,” Delia said. “Now I think of him as close as family.”

Showing the role of red blood cells in living frogs was a difficult problem. Light microscopy cannot see through the mirror-like outer tissue of the liver. Also doesn’t wake up anything from the frog (transparent frog), as red blood cells rush out of the body. Even when the frogs were anesthetized, the liver’s trickery didn’t work.

The answer Delia and Taboada found came from a technique called photoacoustic imaging, which is mostly used by engineers. It reveals hidden inner structures due to subtle vibrations produced by light hitting various molecules and causing a slight release of energy. Duke’s Junjie Yao joined the glass frog team to customize the technique for the frog liver, taking special care not to wake the animal during the process.

Despite the glass frog’s name, transparency among vertebrates may become more extreme, says Sarah Friedman, a fish biologist at NOAA’s Alaska Fisheries Science Center in Seattle.she sent a picture In June, a newly caught spotted snailfish (crystal fish), clear enough on most of its body to show the skin tone and finger lines of her hands as she holds it. It’s not even the best example. The larval stages of tarpon and eels, glass fish and an Asian glass catfish are “almost completely transparent,” said Friedman, who was not involved in the new study.

But these wonders have the advantage of living in water, she said. Evolving delicate vitreous was easier in places where there were not so obvious obvious differences between the bodies of animals and their water houses. Still, it’s cool to have transparent bodies, both on land and at sea.