vertebratesOnline version vertebrates by Luz Álvarez Herrero 1 Mammals 2 Amphibians 3 Fish 4 Birds 5 Reptiles Have hair or fur They usually have four legs Feed their babies with milk Only one of them can fly Have moist skin Only adults have four legs They have scales and use fins to swim They breathe with gills They have two wings Their bodies are covered with feathers They have two legs They have dry, scaly skin Some of them have four legs and some of them have no legs