(i) What are different symmetry that exists in animal kingdom.
(a) Asymmetrical symmetry I. In many animals the body can not be divided in two equal halves on any plane. II. Ex. Amoeba being irregular in shape, some sponges with various branching. Gastropod molluscs (snails, conch) have no symmetry due to torsion in embryonic stage. (b) Radial symmetry I. Any plane passing through a central axis of the body divides the organism into two identical halves. II. Examples are Coelentrates, ctenophores and echinoderms. (c) Bilateral symmetry I. In most animals body can be divided into two equal halves on only one plane, hence body has left and right sides front and rear (back) sides; anterior and posterior ends; dorsal and ventral sides.
