Biologists know of more than 2,300 living species of amphibians. Learn more about the four orders of amphibians with an interesting presentation. It explains the similarities and differences between the thousands of species of...

What features do scientists use to classify animals into groups? Class groups examine a series of paired images of vertebrates (a bass and a trout, a toad and a newt, a crocodile and a tortoise, an owl and a robin, a tiger and a bear)...