bilateral symmetry A type of arrangement of the parts and organs of an animal in which the body can be divided into two halves that are mirror images of each other along one plane only (usually passing through the midline at right angles to the dorsal and ventral surfaces). Bilaterally symmetrical animals are characterized by a type of movement in which one end of the body always leads. In botany this type of symmetry is usually called zygomorphy when applicable to flowers (e.g. foxglove and antirrhinum flowers are zygomorphic). Compare radial symmetry.

bilateral symmetry The arrangement of the body components of an animal such that one plane divides the animal into two halves which are approximate mirror images of each other. Bilateral symmetry is associated with movement in which one end of the animal constantly leads. Sometimes bilateral symmetry is superimposed on another kind of symmetry (e.g. in some echinoids (Echinoidea) where basic pentameral (five-sided) symmetry has a bilateral symmetry superimposed upon it). Compare radial symmetry.

bilateral symmetry The condition, found in many organisms, where one half of the body or structure is the mirror image of the other. Sometimes bilateral symmetry is superimposed on another kind of symmetry, e.g. in some echinoids (Echinoidea) where basic pentameral (five-sided) symmetry has a bilateral symmetry superimposed upon it.

bilateral symmetry The arrangement of the body components of an animal such that one plane divides the animal into two halves which are approximate mirror images of each other. Bilateral symmetry is associated with movement in which one end of the animal constantly leads. Compare RADIAL SYMMETRY.