Bilateral Symmetry
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bilateral symmetry
[bī′lad·ə·rəl ′sim·ə·trē] (biology)
Symmetry such that the body can be divided by one median, or sagittal, dorsoventral plane into equivalent right and left halves, each a mirror image of the other.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
bilateral symmetry
A balanced arrangement of identical similar elements about a central axis.


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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.
Bilateral Symmetry
two-sided symmetry in organisms; manifested in the fact that the body is divided by a medial plane into right and left halves, each of which is the mirror image of the other. Bilateral symmetry occurs among worms, arthropods, and vertebrates and also plant organs—for example, many stems with leaves or lateral shoots arranged in two rows, stems of many cacti, and so on. Leaves in which the upper and lower surfaces differ in structure are also called bilateral.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.