Symmetry
Symmetry, orderly, mutually corresponding arrangement of various
parts of a body, producing a proportionate, balanced form. The principle of
symmetry is of great importance in the fields of biology, mathematics, and
mineralogy.
In biology, the regular distribution of various parts of an
animal's body on two opposite sides of a linear axis, or a median plane, is
known as bilateral symmetry. The proportional arrangement of similar parts of a
body around a central axis, as in the case of jellyfish or starfish, is known
as radial symmetry. The bodies of protozoans, such as those of the order
Radiolaria, which have a round form about a central point or nucleus, are said
to have a spherical symmetry.
In geometry, symmetry is a feature of certain plane and solid
shapes. So-called symmetry operations are those mathematical transformations
that produce a figure identical to the original or a mirror image of the
original figure. Symmetry operations are defined with respect to a given point
(center of symmetry), line (axis of symmetry), and plane (plane of symmetry).
