bilateral symmetry. Symmetrical arrangement, as of an organism or a body part, along a central axis, so that the body is divided into equivalent right and left halves by only one plane Symmetrical arrangement of an organism or part of an organism along a central axis, so that theorganism or part can be divided into two equal halves. Bilateral symmetry is a characteristic of animalsthat are capable of moving freely through their environments.
anatomical parts are arranged on opposite sides of a median axis so that one and only one plane can divide the individual into essentially identical halves.
symmetry in which similar anatomical parts are arranged on opposite sides of a median axis so that only one plane can divide the individual into essentially identical halves
Examples of animals that possess bilateral symmetry are: flatworms, common worms ("ribbon worms"), clams, snails, octopuses, crustaceans, insects, spiders, brachiopods, sea stars, sea urchins, and vertebrates. The symmetry of an animal generally fits its lifestyle