Frogs breathe through their skin.

Today's image features a frog. Frogs don't always get the attention they deserve. These little jumpers have been around since dinosaurs roamed the Earth, and they've evolved into some of the weirdest, coolest creatures out there. With over 4,000 known species worldwide, they come in all shapes and sizes, from the tiny New Guinea Amau frog—smaller than a penny—to the large Goliath frog, which can weigh more than 3 kilograms.

Some, like the glass frog, are nearly transparent, while others are extremely poisonous. The golden poison frog, for example, carries enough toxin to take down ten humans. And if you think all frogs are swamp-dwellers, meet the desert rain frog, a round little amphibian that survives in dry conditions by absorbing moisture through its skin. Frogs play a crucial role in ecosystems by controlling insect populations and serving as prey for many predators. However, habitat loss, pollution and disease threaten many species.