Asymmetrical and Spherical - Metazoa

Some creatures are asymmetrical: no matter which way we try to divide them through the middle, no two halves would appear alike. In simpler words: these are animals which cannot be cut into two identical halves through any plane or axis (longitudinal, sagittal or transverse), Amoeba and most of the poriferans are examples.

At the other extreme, is spherical symmetry. The animals with spherical symmetry can be divided into identical halves along a number of planes which pass through the centre or in other words every plane through the centre will yield two halves which arc mirror images of each other. This type of symmetry is found chiefly in some protozoa and is rare in other groups of animals. Actinophrys and colonial Volvox are typical examples.