radial symmetry The arrangement of parts in an organ or organism such that cutting through the centre of the structure in any direction produces two halves that are mirror images of each other. The stems and roots of plants usually show radial symmetry, while all animals belonging to the Cnidaria (e.g. jellyfish) and Echinodermata (e.g. starfish) are radially symmetrical – and typically sessile – in their adult form. The term actinomorphy is used to describe radial symmetry in flowers (e.g. a buttercup flower). Compare bilateral symmetry.

radial symmetry The arrangement of the body of an animal in which parts are arranged symmetrically around a central axis. Such an arrangement allows the animal to interact with its environment from all directions. It is most commonly associated with a sessile way of life. Compare bilateral symmetry.

radial symmetry The arrangement of the body of an animal in which parts are arranged symmetrically around a central axis. Such an arrangement allows the animal to interact with its environment from all directions. It is most commonly associated with a sessile way of life. Compare BILATERAL SYMMETRY.

radial symmetry The condition in which the body of an organism is repeated in a circular manner. In corals the repetition occurs around the mouth, and in some echinoderms (Echinodermata), where the five rays of the animal are symmetrically placed, the symmetry is also radial.