AmphibiansAmphibians are vertebrates that spend part of their lives under water and the remainder on land. The word amphibians means living in two places. Amphibians are cold-blooded. Their body temperature depends on the temperature of their environment.
When they are young, amphibians have gills to take oxygen from the water. When they grow up, most amphibians develop lungs that allow them to take oxygen from the air. Amphibians usually have moist skin with no scales.
There are three groups of living amphibians: newts and salamanders; frogs and toads; and caecilians.
ReptilesReptiles are a group of animals that have scales, breathe air, and usually lay eggs. Reptiles are cold blooded. They have dry, thick and scaly skin. Reptiles breathe with lungs. Snakes, lizards and turtles are reptiles.
BirdsBirds are warm-blooded vertebrate animals that have wings, feathers, a beak, no teeth a skeleton in which many bones are fused together or are absent, and an extremely efficient, one-way breathing system. Flying birds have strong, hollow bones and powerful flight muscles.
Most birds can fly. Birds have a very strong heart and an efficient way of breathing - these are necessary for birds to fly. Birds also use a lot of energy while flying and need to eat a lot of food to power their flight.
Birds hatch from eggs. Most birds build nests in which they lay their eggs. Birds breathe with lungs. Most birds can fly, some can run very well, some swim, and some do combinations of these. Some birds cannot fly.
Flying birdís wings are shaped to provide lift, allowing them to fly. These light-weight animals have adapted to their environment by flying, which makes them efficient hunters, lets them escape from hungry predators, and takes them away from harsh weather. Robins, cardinals, chickens and eagles are some examples of birds.
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