radial symmetry

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radial symmetry

biology

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July 13, 2026

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In biology, radial symmetry describes an arrangement where body parts radiate from a central axis, like spokes on a wheel. This means an organism can be divided into equal halves by any plane passing through this central axis. Organisms with radial symmetry, such as starfish and jellyfish, typically have a distinct top and bottom but no clear front or back. This body plan is common in aquatic animals like cnidarians and echinoderms.123

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symmetry
Symmetry in animals
In radial symmetry the body has the general form of a short or long cylinder or bowl, with a central axis from which the body parts radiate or along which they are arranged in regular fashion. The main axis is heteropolar—i.e., with unlike ends, one of…
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In radial symmetry the body has the general form of a short or long cylinder or bowl, with a central axis from which the body parts radiate or along which they are arranged in regular fashion. The main axis is heteropolar—i.e., with unlike ends, one of…
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angiosperm
The corolla
…each other, the flower has radial symmetry, and the flower is called regular or actinomorphic (e.g., buttercup, Ranunculus; Ranunculaceae). In regular flowers, any line drawn through the centre will divide the flower into two identical halves. When at least one petal of the corolla is different, the flower has bilateral…
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…each other, the flower has radial symmetry, and the flower is called regular or actinomorphic (e.g., buttercup, Ranunculus; Ranunculaceae). In regular flowers, any line drawn through the centre will divide the flower into two identical halves. When at least one petal of the corolla is different, the flower has bilateral…
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echinoderm
Symmetry and body form
A tendency toward radial symmetry (the arrangement of body parts as rays) developed early in echinoderm evolution and eventually became superimposed upon the fundamental bilateral symmetry, often obliterating it. Radial pentamerous symmetry is conspicuous among all groups of living echinoderms. Although the reasons for the success of radial…
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A tendency toward radial symmetry (the arrangement of body parts as rays) developed early in echinoderm evolution and eventually became superimposed upon the fundamental bilateral symmetry, often obliterating it. Radial pentamerous symmetry is conspicuous among all groups of living echinoderms. Although the reasons for the success of radial…
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Fabales
Mimoseae
…flowers of the family are radially symmetric and are usually most easily recognized by the long stamens that extend beyond the rest of the flower. The calyx and corolla are both valvate in bud, contrasting with the usual condition in both of the other subfamilies. The petals are small and…
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…flowers of the family are radially symmetric and are usually most easily recognized by the long stamens that extend beyond the rest of the flower. The calyx and corolla are both valvate in bud, contrasting with the usual condition in both of the other subfamilies. The petals are small and…
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