The body of the animal can be divided into identical halves in only one plane is:

If the body of an animal cannot be divided into identical halves, then the animal is called asymmetric. Example - Sponges.
If the body of the animal can be divided into identical halves in only one plane, then the animal is called bilaterally symmetrical. Example - Flatworms and roundworms.
If the body of the animal can be divided into identical halves along many planes, i.e. multiple radii, then the animal is called radially symmetrical. Example- Coelenterates and Cnidarians.
If the body of the animal can be divided into identical halves along only two planes, i.e., only two radii then the animal is said to be biradially symmetrical. Example - Sea anemone.