The animal kingdom is divided in two major groups: Vertebrates and Invertebrates. The difference between them is that vertebrates have backbone and invertebrates haven’t it.

Vertebrates: This type of animals is divided in : Mammals, Birds, Reptiles, Anphibians and Fishes. Only the mammals are viviparous (their youngs born directly from their mother’s body). The rest,birds, reptiles,anphibians and fishes are oviparous (their youngs born from an egg).

Invertebrates: This kind of animals haven’t got backbone. They are divided in 4 main groups: Artrophods, that could be: Insects, Aracnids, Myriapods and Crustaceans. Molluscs. Equinoderms. Anelids.