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Symmetry, in biology, the repetition of the parts in an animal or plant in an orderly fashion. Specifically, symmetry refers to a correspondence of body parts, in size, shape, and relative position, on opposite sides of a dividing line or distributed around a central point or axis.
- The Editors of Encyclopaedia Britannica
Feb 13, 2017 · Bilateral symmetry refers to organisms with body shapes that are mirror images along a midline called the sagittal plane. The internal organs, however, are not necessarily distributed symmetrically.
- Asymmetrical Symmetry: In some animals there are no body axis and no plane of symmetry, hence the animals are called asymmetrical. The amoeboid forms (e.g., Amoeba) and many sponges have irregular growth pattern of the body and cannot be divided into two equal halves (Fig.
- Spherical Symmetry: In spherical symmetry the shape of the body is spherical and lack any axis. The body can be divided into two identical halves in any plane that runs through the organism’s centre.
- Radial Symmetry: In radial symmetry the body can be divided into two roughly equal halves by any one of many vertical planes passing through the central axis (Fig.
- Biradial Symmetry: The body of animals which exhibits biradial symmetry, represents a combination of both radial and bilateral symmetry. The organs are arranged radially and the body can be divided into two by a mid-longitudinal plane.
Mar 13, 2021 · Examples of Radial Symmetry. There are relatively few examples of radial symmetry in the animal kingdom. Animals that display radial symmetry usually belong to the phyla Ctenophora or Cnidaria. Ctenophora is a phylum of invertebrate animals more commonly known as the comb jellies.
- Kate Latham
Aug 4, 2022 · In biology, symmetry is approximate. For example, plant leaves, while considered symmetric, will rarely match up exactly when folded in half. Furthermore, symmetry may refer only to the external form and not the internal anatomy.
Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, the face of a human being has a plane of symmetry down its centre, or a pine cone displays a clear symmetrical spiral pattern.
Jun 14, 2020 · The most visible examples of radial symmetry in nature are actinomorphic flowers. The shape of a flower is not at all random. While color and scent can provide other means of attraction, actinomorphism gives a flower the greatest chance of pollination by multiple species.
