Question

Find the axis of symmetry.

Answer 1

Hint The body of the animals shows symmetry in the organization. The body plan can be divided into the radial symmetry, bilateral symmetry, and asymmetrical. Only sponges have asymmetry present in them which means they are not symmetrical in their body plans.

Complete answer: Radial symmetry occurs when the body can be divided into the upper and lower half or can be divided in the form of sun rays. There is no identical part in this symmetry. This is usually found in the cnidarians and Ctenophora. This symmetry helps the organism to move at a very slow pace. Bilateral symmetry is when the body of the organism can be divided into two identical parts. This symmetry helps the organism to move fast around in a particular direction. In the image given it can be divided into two equal halves. And each half would have a circle present each. So the symmetry is the bilateral symmetry and the axis will pass in the middle of the outer circle. There are some organisms which lack any symmetry or have an absence of symmetry in their body structure. Such organisms are called asymmetrical organisms. The sponges are the only organism to have this type of symmetry present.

Note: The bilateral symmetry was formed in the organism due to the evolution that took place. The organisms earlier present didn’t have a distinct head region. The accumulation of the nerves in the head region leads to the formation of a distinct head in the organism.