bilateral symmetry

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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.

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