Everyone is familiar with many of our common animals and knows something about where and how they, live with the Variety of animals life species but few people realize how many different kinds of animals there are and how greatly and Variety of animals life species vary in size, shape, structure, and habits. It is easy to observe the larger types such as cats, birds, frogs, and even some of the smaller ones such as earthworms and flies, but a considerable part of the animal kingdom consists of forms so minute that they can be seen only with the aid of the microscope. Then there are forms that live in the soil, in the ocean, or in other places where we do not ordinarily see them.
How Many Different kind of Animals exists in Variety of animals life species?
No one knows exactly how many different kinds of animals there are now in existence but we do know that more than one million have been described by zoologists. Fortunately for us, although they differ from each other sufficiently to be recognized as distinct kinds (species) , they possess characteristics in common and can be arranged in groups. The principal groups are called phyla (singular, phylum). Zoologists are not in agreement with respect to the number of phyla into which the animal kingdom should be divided, but usually 11 are studied in some detail in a beginning zoology course. Besides these, there are a few groups of animals of more or less uncertain relationships such as the Rotifera and Bryozoa.
For each phylum, the approximate number of known living species is given. Arthropoda comprise about three fourths of all the species of animals. About 97 per cent of the Arthropoda are insects. Among the other phyla, the Mollusca (snails, clams, etc.), Chordata (fish, birds, mammals, etc.), and Protozoa (one-celled animals) are the most numerous. The numbers given are estimates by specialists, but no one knows exactly how many species have been described in any phylum