Summary:
- amphibians are the first vertebrates to evolve from life in the sea to life on land.
- There are about 6,200 known species of living amphibians.
- They are classified into three orders: frogs and toads, salamanders and newts, and caecilians.
- Caecilian are the only amphibians without legs and live in the water or soil.
- They have a long, worm-like body without legs, and are adapted for walking and swimming rather than jumping.
- Salamander and newt may walk or swim.