When tiny glass frogs come in at night, they can become transparent by hiding nearly 90 percent of their red blood cells.
The colorful areas are tucked away in the frog’s liver, which may hide the cells, according to a study published Thursday in the journal Science.
These are during the day little frogs spend their time hanging under tree leaves. At that point, their green-colored forms cast no shadows, making them largely invisible to potential predators.
When tiny glass frogs come in at night, they can become transparent by hiding nearly 90 percent of their red blood cells. Above: A female glass frog is shown with eggs in her transparent ovaries, photographed from below with a flash
However, once they wake up, the frogs look more reddish brown.
“If they’re transparent, it’s for their safety,” said Junjie Yao, a Duke University biomedical engineer and co-author. When awake, they can actively evade predators, but when they are asleep and most vulnerable, they have “adapted to remain hidden.”
Scientists used light and ultrasound imaging technology to unlock a new insight: The frogs can “concentrate,” or hide, nearly 90 percent of their red blood cells in their livers while they sleep.
That circulating blood would otherwise betray them. Yao also pointed out that the frogs can shrink and compress most of their internal organs.
The study “beautifully explains” how “glass frogs hide blood in the liver to preserve transparency,” Juan Manuel Guayasamin, a frog biologist at the University of San Francisco in Quito, Ecuador, who was not involved in the study, told the Associated Press.
The colorful areas are tucked away in the frog’s liver, which may obscure the cells, according to a study published Thursday in the journal Science. Above: A glass frog sits on a leaf
Scientists used light and ultrasound imaging technology to unlock a new insight: The frogs can “concentrate,” or hide, nearly 90 percent of their red blood cells in their livers while they sleep. Above: A male glass frog is photographed from below
How they manage to accomplish this feat is still somewhat mysterious.
For most animals, very little blood circulating oxygen for a few hours would be fatal – and concentrating blood so tightly would result in fatal clotting. However, the frogs can survive.
Researchers believe that future studies on the species could provide information for the development of anticoagulant drugs.
“Transparency is extremely rare in nature, and in terrestrial animals it’s essentially unheard of outside of the glass frog,” said Oxford University biologist Richard Whitem, who was not involved in the study.
Those that are transparent include some fish, shrimp, jellyfish, worms, and insects—none of which move large amounts of red blood through their bodies.
“It’s just this really amazing, dynamic form of camouflage,” White said.
“Transparency is extremely rare in nature, and in terrestrial animals it’s essentially unheard of outside of the glass frog,” said Oxford University biologist Richard Whitem, who was not involved in the study. Above: A leaf-dwelling glass frog is shown
Above: A collection of researchers’ photos shows the same frog asleep, under anesthesia, and while active (in transmitted light), showing the difference between red blood cells in circulation