What is radial symmetry?

2 Answers
Apr 4, 2017

radial symmetry is a body system found in several invertebrates


Radial like radial tires conveys the idea of a circle. Organisms with radial symmetry have rotational symmetry. If the organism is rotated in a circle it will look the same at more than point on the circle.

Sea Stars and other organisms in that phylum have a five star radial symmetry. The organism can be divided equally in five different ways.

Jelly's (so called jelly fish) also called Medussa have circular radial symmetry. These organisms can be divided across the circle in multiple ways.

Mammals in contrast have bilateral symmetry. Vertebrates can only be divided equally along one line, dividing the organism into two (bi) equal parts.

Apr 4, 2017

Radial symmetry is seen in aquatic animals: these are mostly bottom-dwelling as well. Please note that organisms with radial symmetry has oral and aboral sides and a central axis passes through the body.

Body of an animal with radial symmetry could be divided in two equal halves by cutting through any plane passing through central axis. Such an organism has no left/right/ or anterior/posterior distinction. Members of Phylum Cnidaria show radial symmetry, such as a Hydra.



Many cnidarians like sea anemones are biradially symmetrical, i.e. their body could be divided in equal parts by cutting through only two radial planes.

Another group of animals belonging to Phylum Echinodermata show pentaradial symmetry, i.e. their body can be equally divided by cutting through specific five radii.