Bilateral symmetry applies to specimens that are symmetrical along a single line. This line may run in either a vertical or horizontal direction.
Radial symmetry applies to specimens that have symmetry about numerous axes, generally extending from the center of the object.
Translational symmetry is similar to bilateral symmetry, but the reflection is shifted or translated, so that the reflection appears to have been slid along the axis of symmetry.
Helical symmetry is the type of symmetry seen in springs, Slinky toys, and drill bits. It is rotational (radial) symmetry along with translation along the axis of rotation.
Asymmetrical specimens have no line of reflection.
Some entities are so variable that they may fall into more than one of these categories. One piece may have bilateral symmetry while other pieces are asymmetrical. Feel free to choose multiple states if this applies to your specimen.
Authors: A.O. Tucker, A.J. Redford, J.L. Scher, M.D. Trice
Last updated: January 2020
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