Radial Symmetry Definition

When the body plan of any organism is divisible into two identical parts around the central axis, the form of symmetry is called radial symmetry.

In biology, the regularity of body parts in a plane or around an axis is defined as symmetry. The symmetrical organism can be defined as the organism having a balanced distribution of similar parts on both sides of the axis.

Sometimes it can also be an approximate repetition instead of an exact duplicate. Bilateral symmetry in humans and some other animals are a common example of symmetry.

When each side around the plane exhibits regularity of parts around a central axis, the symmetry is called radial symmetry.

The radial symmetry does not contain left and right sides. There is fewer animal consist radial symmetry as compared to the bilateral symmetry that can be seen in most of the organisms.

Examples of organisms having radial symmetry include starfish, sea anemones, jellyfish, and sea urchins. Some flowers also exhibit radial symmetry.

In some cases, radial symmetry also exhibits in special forms such as tetramerism (having four identical parts) and pentamerism (which consists of five identical parts).

The combination of radial and bilateral symmetry is called biradial symmetry that can be seen in Ctenophores (comb jellies).