According to the biology department of the State University of New York, roundworms have bilateral symmetry. Bilateral symmetry means that one vertical cut can split the animal into two equal halves.
Radial symmetry is another form of symmetry that occurs when the body parts of an animal are arranged around a central axis so that a cut along any axis can produce two identical halves. If an animal is asymmetrical, it does not have any type of symmetry and can never be cut into two identical halves.
The type of symmetry that an animal has is related to its movement or lack thereof. For example, organisms with radial symmetry are generally immobile. The presence of multiple parts around a central axis permits the organism to extend in every direction, helping it get necessary nutrients. Examples of organisms with radial symmetry are starfish and sea urchins.
Bilateral symmetry is often seen in animals that are motile. The symmetry helps the body be streamlined, allowing the organism to move. Two organisms that have bilateral symmetry other than the roundworm are butterflies and crabs.
Asymmetry is seen in both motile and immobile organisms. Motile organisms with no symmetry are the narwhal, flounder and sperm whale. Asymmetrical immobile organisms are the sponge and coral.