People need to live on the land, and fish need to live in the water. It's a biological necessity based on lungs in the first and gills in the second.

Amphibians, however, are a group of creatures able to live on land or in the water. Their name comes from the Greek word "amphibios," meaning "living a double life." Scientists believe the many different species we now know date back millions of years. They have made their way around the globe, except for Antarctica and Greenland.

Frogs are the most widespread. You can find them in deserts, rain forests, and even high on mountains.

Most amphibians breed in water. The eggs develop into tadpoles. Tadpoles breathe through gills until they develop lungs for breathing on land. The process of change is called "metamorphosis."

Despite the name, there are actually some species that are permanent land dwellers, and others exist completely in an aquatic environment.