Animals are divided into invertebrates and vertebrates. The invertebrates are the animals that do not posses a backbone or vertebral column while the vertebrates do. Vertebrates are usually larger than the invertebrates and have a more complex body organization and structure. It includes mainly five classes: amphibian, fishes, reptiles, birds and mammals.

Amphibians They have a smooth, scales-less and moist skin and legs When they are larvae, they live in water and use gills to breathe. When they become adults, they will live on land and have lungs and moist skin for breathing. They carry out external fertilisation. They are cold-blooded that their body temperatures changes with the surrounding.

Fishes They live in water and their bodies are covered with wet scales. They have gills for breathing and fins for swimming that can maintain balance. They carry out external fertilisation. They are cold-blooded.

Reptiles They have a hard, dry scaly skin. They use lungs for breathing. They carry out internal fertilisation. The females lay eggs on land which enclosed in hard shells. They are cold-blooded.

Birds Their bodies and legs are covered with feathers and dry scales respectively. They have lungs for breathing. They have a beak but no teeth. Their forelimbs are modified to wings. They carry out internal fertilisation and their eggs are enclosed in chalky shells. They are warm-blooded that their body temperatures are constant and are independent of the surrounding temperature.

Mammals They have hair on their skin. They use lungs for breathing. They have a diaphragm. They carry out internal fertilisation and the young are born alive. -Babies are developed inside the body of the mother with the embryo. -Young are fed on milk with their mothers’ mammary glands. They are warm-blooded.

If it is I would like to be…

Do you know what is ?

Ichthyosaurus were a kind of animals that living in the sea which belonged to reptiles.They looked like dolphins and their bodies were well-designed that suitable for them to swim.Their speed was so high even though they weighted about 3 tonnes.Most of the Ichthyosaurus were used to catch fishes with their sharp teeth and long mouth.They can produce fertile offspring by borning the babies alive in the sea.