Glass frogs are one of only a few animals that are transparent on land. (Another is the dazzling glasswing butterfly.) Why is that?

It turns out being clear isn’t always an asset. Light refracts when it enters a transparent surface at an angle. Think of sunshine on a glass window. If you stand at a certain angle, you’ll see a bright glare.

No animal wants to sparkle or create glare. That would give its location away to predators. God gives land animals other crafty ways to hide.

Jaguars in Brazil blend in perfectly against the backdrop of dappled sunlight, tall grasses, and vines. Vietnamese mossy frogs merge into their evergreen rainforest home. A thick coat of white fur conceals Arctic hares in snow.

Most transparent animals live in the ocean. Water doesn’t strongly refract light. A piece of glass underwater is hard to see. Water prevents the glare.

Sea walnuts are clear jellyfish that are just three to five inches long. Good news! They never sting in self defense. That’s partly because they can easily hide from animals of prey.

The glass squid lives in slightly sunlit waters. Many of these squid have light organs under their eyes that hide their body shadows. Animals looking up for a tasty snack miss the shadows and see light shining out the squid’s sides. Predators move on in search of other morsels.

Crocodile icefish live around Antarctica. They are the only known vertebrates with no hemoglobin in their blood. Both their bodies and blood are colorless. That makes it easy for them to ambush their prey.