Some ocean animals have a clever form of camouflage—they're transparent.

But being see-through is far less common on land.

"And there's a few reasons why that may be." Jim Barnett is a postdoctoral research fellow at McMaster University in Ontario,Canada.

(He began this research as a doctoral student at the University of Bristol .) "Differences between air and water as a surrounding medium means that light interacts differently with a transparent organism's body tissues."In the ocean,light is always coming from above,and the background is less variable.

But in jungle canopy,light is coming from many directions, and the background is far more variable.

Enter a little critter called the glass frog.

It's not actually transparent;it's translucent.

That means its skin in some places is thin enough that you can actually see its internal organs hard at work.

"Most of the time,when you see photographs of these frogs, they're taken under quite controlled conditions,with either strong lighting,like a powerful flash, or they're photographed from underneath on a piece of glass,and it's really their bellies which are transparent.

And these frogs are pretty small and thin and quite delicate, so if you have a powerful flash on your camera,you can sort of just blast light through them,and they will look pretty transparent." Barnett says the frog's translucent skin is actually a novel camouflage strategy that no one's ever really studied—until now.