A Brief Introduction to the Animal World Animals are living organisms found in literally all of the Earth's habitats ()including the depths of the oceans,the freezing Arctic,and even within other animals and plants. The animal kingdom is divided up into animals without backbones(invertebrates)which include lobsters and snails,and animals that do have backbones(vertebrates),animals like monkeys and zebras.Invertebrates make 97 per cent of all animal species. The animal kingdom is divided into about 30 phyla ()The nine largest phyla contain the majority of species.One phyla,the arthropods (节肢a动物)，which includes insects and spiders,constitutes about75 percent of all known animal species.The largest group within the phyla of arthropods and the most diverse class in all kingdoms,is insects. 22 A Brief Introduction to the Animal World Animals are living organisms found in literally all of the Earth’s habitats（栖息地）, including the depths of the oceans, the freezing Arctic, and even within other animals and plants. The animal kingdom is divided up into animals without backbones (invertebrates) which include lobsters and snails, and animals that do have backbones (vertebrates), animals like monkeys and zebras. Invertebrates make 97 per cent of all animal species. The animal kingdom is divided into about 30 phyla （门）. The nine largest phyla contain the majority of species. One phyla, the arthropods （节肢动物）, which includes insects and spiders, constitutes about 75 percent of all known animal species. The largest group within the phyla of arthropods and the most diverse class in all kingdoms, is insects