They also have an endoskeleton made of either bone or cartilage. An internal skeleton provides the vertebrates with strong, flexible support. Vertebrates have adapted to many different environments. They are found in the air, on land, and in water. To find out more about each group click on the icons.
Fish have special breathing organs called gills, that absorb oxygen from water.
Amphibians begin their lives in the water. As they mature, they develop lungs and live part of the time on land. Reptiles are found mostly on land. They are covered with scales, which help keep them from drying out. Birds have feathers, wings, and porous bones, that allow them to fly.