What determines the type of body symmetry in animals?

Scientists are carefully studying how the body parts of the animal are located. They use this information to determine how animals are related and to group living things into different categories. There are several different types of symmetry, including asymmetry, radial symmetry, bilateral symmetry, biradial symmetry, and spherical symmetry.

Symmetry is often imperfect because we are dealing with living things, but you may notice that certain body parts are on either side of the imaginary midline.