Introduction
Every organisms living on this earth is unique in itself. This uniqueness of each living individual is the basis of the great differences or diversity of the living world. The type of living organism found in one place is entirely different from organisms found in another place. For example, animals found in plains is different from the animals found in mountains or hilly regions. In fact different places, in different part of the world have their own typical kind of living Organisms. The degree of diversity in the living world is endless.
Different Types of Animals
With such vast differences and large number, it is very difficult to study each and every living organism separately, at the individual level. Therefore to study and understand the life of animals effectively they have been classified into different groups, on the basis of certain criteria.
Classification of Animal Kingdom
The animals are broadly divided into two major groups based on the presence or absence of the major characteristic feature, that is, the back bone.
Invertebrates
Invertebrates are those animals which do not have a backbone or vertebral column. They are considered to be primitive form of life on the earth. A large variety of small animals like insects, worms, slugs, snail, spider and scorpion etc. belong to this group. A surprising fact is, earth is home to more insects than any other kind of animal. Insets are very unique, among all living creatures on the Earth.
Different Types of Invertebrates
The body of an insect is divided into three parts head, thorax and the abdomen. The head contains the mouth, the eyes and the antennas. Some insects use their antennas for smelling. The thorax of an insect is similar to our chest. If an insect has wings, they are attached to this portion of the body i.e. thorax. The abdomen contains the large part of the digestive system. As the invertebrates lack bones, they have hard outer covering to support the body called chitin. This outer layer is waxy and waterproof. All insects have six legs. Invertebrates are found everywhere on the earth, land, water, air etc.
Vertebrates
The animals which have a back bone or a vertebral column are called vertebrates. These animals are highly evolved and have well developed organ system. Vertebrate is a large group. To study and understand the animals in this group, vertebrates are further divided into five major groups.
Fish
As the name suggest, these animals live
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