What is the significance of radial symmetry

In the feather star shown in the image, you can see five distinctive "branches" radiating from the star's central disk. Animals with biradial symmetry show a combination of radial and bilateral symmetry. A biradially symmetrical organism can be divided into four parts along a central plane but each of the parts is equal to the part on the opposite side but not the part on its adjacent side.

Radially symmetrical animals have a top and bottom but don't have a front or back or distinctive left and right sides. They also have a side with a mouth, called the oral side, and a side without the mouth called the aboral side. These animals typically can move in all directions. You can contrast this to bilaterally symmetrical organisms like humans, seals or whales, who usually move forward or backward and have a well-defined front, back and right and left sides. While radially symmetrical organisms can move easily in all directions, they may move slowly, if at all.

Jellyfish primarily drift with waves and currents, sea stars move relatively slowly compared to most bilaterally symmetrical animals, and sea anemones barely move at all. Rather than a centralized nervous system, radially symmetrical organisms have sensory structures scattered around their body.

Sea stars, for example, have eyespots at the end of each of their arms, rather than in a "head" region. One advantage of radial symmetry is that it may make it easier for organisms to regenerate lost body parts.

Sea stars , for example, can regenerate a lost arm or even an entirely new body as long as a portion of their central disk is still present.

Marine animals that exhibit radial symmetry include:. Actively scan device characteristics for identification. Use precise geolocation data. Select personalised content.

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