The See-Through Frog's Disco Liver

Breaking news: Glass frogs are even more mind-blowing than we thought.

Just to remind you that I don’t only write about deer, I wanted to alert you to a brand new story I just had published at National Geographic. It’s about see-through frogs and their disco livers.

But none of those words make sense together, you may be thinking. Okay, lemme back up.

In Central and South America, there are these amphibians known as glass frogs. There are many different species, but lots of them have this super weird biological quirk—their skin and muscles are varying degrees of see-through. On top, the buggers are translucent, which helps them blend into the leaves they sit upon. But underneath, these animals can be straight-up transparent, which means you can actually see their beating hearts and other assorted organs. Truly, these animals are just all kinds of bonkers.

Image by Jesse Delia, which includes several different kinds of glass frog, viewed from below

Now, as if being see-through wasn’t impressive enough, scientists have just discovered one of the anatomical tricks these animals use to disappear.

During the day, while the glass frog sleeps, it takes almost all of its red blood cells and hides them inside its liver, which is itself covered in guanine crystals that scatter light and prevent the bright-red blood from showing through its see-through tissues. With the blood cells hidden, the frogs become 2 to 3 times more transparent than they are while exercising and with red blood a-flowing!

This! Is! Mind-blowing!

The frog on the right has blood flowing and is ready to rock. The frog on the left has hidden virtually all of its red blood cells in its disco liver. Image: Jesse Delia

For one, red blood cells transport oxygen to the rest of the body, so every time these frogs pull their little disappearing act, the scientists think the animals are essentially dropping into a sort of torpor, which is a bit like hibernation. And that means that unlike virtually all other kinds of frogs, which are well, jumpy, glass frogs are total sleepy heads. Not only can you sneak up on the snoozers, but it takes several pokes with a finger to get them to budge. Possibly because they literally don’t have the oxygen flowing through their system to allow for movement! *head explode emoji*

Also neat? When the scientists gave the frogs anasthesia so they could image them better, the animals weren’t able to hide their blood cells.

A sleeping glass frog has very little oxygen circulating its body while asleep. But the frog on the right, which has been given anasthesia, is full of O2. Image courtesy of Jesse Delia.

Now, because the frogs have found a way to stuff all of their red blood cells into a tiny place without developing a life-ending clot, the scientists say these little leapers may hold the key to one of the most sought after drugs in all of medicine — a compound that would allow us to prevent blood clots while also avoiding excessive bleeding. Such a drug is considered to be the “Holy Grail of Hematology.”

If you’d like to learn more, hop on over to my story at National Geographic!

It’s me. Hi.

Remember the vinegaroons? A few weeks ago in this newsletter, we talked about the pink-boxing-glove wearing babies, but if you’d like to learn more about these fascinating and mostly harmlss arachnids, I just wrote a new reference page for the critters over at National Geographic. Enjoy!