Scientists already knew that glass frogs appear see-through. Now they know this too: The amphibians can turn their “see-throughness” on and off.

Now you see them. Now you don’t.

Glass frogs live in South and Central America. Just try to spot these nocturnal frogs in the daytime. They hang underneath tree leaves, fast asleep. God designed them so that their lightweight, transparent bodies don’t even cast shadows. Birds and other predators passing overhead or underneath don’t notice them. They look right through them!

At night, the frogs wake up. They are no longer so see-through. A reddish-brown color comes back to their bodies. They hop around searching for insects and mates.

“When they’re transparent, it’s for their safety,” says Junjie Yao, a scientist who studies the frogs. When awake, the frogs can evade predators. But when they’re sleeping and most vulnerable, their see-through skin keeps them hidden.

But here’s the question: How do they do it? The frogs’ skin is transparent. Their blood isn’t. This blood circulating through their bodies would give them away. Researchers discover part of the secret: While asleep, the frogs “hide” nearly 90 percent of their red blood cells in their livers. The frogs also pack together most of their internal organs.

Blood carries oxygen to the rest of the body. No circulation for several hours would kill most animals. Yet somehow, the frogs survive. Again: How? That remains a mystery.

Scientists watch to see what these creatures might teach us.

If you lie down, you will not be afraid; when you lie down, your sleep will be sweet. — Proverbs 3:24

Why? God provides even His smallest creatures with remarkable traits, like camouflage to protect from predators.