Radial symmetry is, usually, exhibited in animals which (a) are attached to the substratum (b) have one opening of alimentary canal (c) live in water (d) have ciliary mode of feeding.
Option A The organisms attached to the substratum possess radial symmetry in all vertical planes. All the animals belonging to cnidaria (e.g. jellyfish) and echinodermata (e.g. starfish) are radially symmetrical and typically sessile in their adult form. In radial symmetry the parts in an organ or organism when cut through the centre in any direction produces two halves that are mirror images of each other.
