Question

How do the body planes divide the body?

Answer 1

Hint: Organisms exhibit diversity on various parameters. Body symmetry is one of them. An organism is said to be symmetrical when an imaginary axis/plane can divide it into equal parts. Symmetry can also be seen in the internal features of some organisms. These parts can be mirror images of one another.

Complete answer:
The different types of symmetry seen in nature include radial symmetry, bilateral symmetry, spherical symmetry, and biradial symmetry.
An organism is said to be showing radial symmetry when the imaginary axes or planes can pass through the centre of the body to form the segments. The animals that show this symmetry usually have somewhat flattened bodies. This type of symmetry is shown in most animals that belong to the phylum Cnidaria or Echinodermata.
Bilateral symmetry is seen when an imaginary axis can divide the body into two halves. Humans have bilateral symmetry. In this type of symmetry, the ventral, dorsal, anterior, and posterior sides of the body are also noted. The ventral side refers to the side where the belly is located. Dorsal is the side where the vertebral column is located.
Anterior refers to the mouth and posterior refers to the anus. For humans, the anterior and the ventral are on the same side of the body. Posterior and anus are on the same side. For legged animals that’s not the case.
Biradial symmetry is when the organism shows both bilateral symmetry and radial symmetry. The organisms of the phylum Ctenophora show this symmetry.
Spherical symmetry is seen in organisms that look somewhat spherical in shape. A good example of an organism that shows this symmetry is Volvox. The organism will divide into equal segments when an imaginary plane passes through the centre.

Note: Symmetry is aesthetically pleasing. This is one of the parameters on which many organisms choose their mate. Therefore, having symmetrical features gave an organism advantage over the other. However, not all organisms show symmetry. Organisms such as amoeba, sponges do not show any symmetry.
Viruses are not classified as organisms but they also show symmetry. Icosahedral symmetry is a special symmetry seen in viruses.