Question

When the body of the animal can be divided into identical halves in only one plane then it is termed as:

• A. Asymmetry
• B. Bilateral symmetry
• C. Radial symmetry
• D. Biradial symmetry

Answer 1

Answer: (B)

Bilateral symmetry

• 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.

Hence, the correct option is B.