The body is metamerically segmented. The body becomes divided transversely into a number of similar parts or segments. The subdivisions may be indicated externally by constrictions of the body surface.
The name nematode means “pointed ends”. The animals included in this group have elongated worm like body with pointed ends. The nematodes are triploblastic and pseudocoelomates. One end of the body is anterior, however the head is not clearly marked and there are no special sense organs at this end
The platyhelminthes are triploblastic acoelomates. There is development f a third layer, the mesoderm, which separates the ectoderm and endoderm. The playhelminthes exhibit bilateral symmetry, and body is unsegmented.
For example, in Obelia there are feeding individuals, the gastrozooids; the individuals capable of asexual reproduction only, the gonozooids, blastostyles and free-living or sexually reproducing individuals, the medusa…..
Cnidarians have double layer organization and are therefore diploblastic having tissue grade organization and have organs. During the development two germinal layers are formed the outer ectoderm and inner endoderm from which their bodies are constructed.
These animals are composed of many cells however there is no tissue organization and have no organs. Sponges lack symmetry. In most sponges the body wall is formed of an outer layer, pinacoderm, made up of cells called pinacocytes:
Diploblastic animals belong to division radiata. The body of these animals consists of two layers of cells, ectoderm and endoderm. There is a jelly like mesenchyme or mesogloea which in most cases is non cellular. Diploblastic animals show lesser degree of specialization and they do not form specialized organs.
This group includes animals with bilateria symmetry. In an animal where the right side is approximately the same as the left side and where there is a distinct anterior end is said to have bilateral symmetry. The animal can be divided into two equal parts by an imaginary line only in one plane.
In traditional two-kingdom systems, the multicellular animals were referred to broadly as Metazoa to distinguish them from one-celled animals, the Protozoa. In this text book we have followed the five kingdom classification system introduced by Robert Whittaker. In this system of classification the traditional Protozoa belong to kingdom Protoctista
Bambusa (Bamboo) are used as building material for the thatching huts, making boats, carts, pipes etc. and the split stem are woven into mats, baskets, fans, hats, course umbrella. Leaves are also given to horses as a cure of cough and cold etc. certain grasses yield aromatic oils, e.g.
