Radial symmetry
In biology, the term radial symmetry is used for cylindrical symmetry of multicellular organisms, a characteristic that is used to help classify them. It refers to the fact that it's possible to make any cut through the center of the organism, with the plane of the cut going from the top to the bottom (dorsal to ventral), and result in roughly equal halves in terms of organs and/or body parts. (Multi-layered circular pies exhibit radial symmetry.)
Organisms with radial symmetry only have a single orientation: dorsal-ventral (or anterior-posterior, there is no differentiation). Organisms with bilateral symmetry, on the other hand, have two orientations: dorsal-ventral, as well as anterior-posterior. Jellyfish and ctenophores are the only animals with true radial symmetry; echinoderms have partial radial symmetry.
- See also: bilateral symmetry, pentamerism
