About 400 million years ago, the first four-legged creatures (Tetrapods) began to make the transition from life in the water to life on land. One of the earliest groups to evolve from the Tetrapods was the amphibians. The frogs, which include toads, are the most recognizable and diverse of the amphibians. Globally, there are more than 7,200 species of frogs with 28 species occurring in Virginia. Except for Antarctica, they are found on every continent and in almost every imaginable habitat on earth, from arid deserts to boreal forests. The only habitats frogs do not occupy are those associated with saltwater environments.