Question

The adult animal in this phylum is radially symmetrical, but its larva exhibits bilateral symmetry
A.Echinodermata
B.Coelenterate
C.Arthropoda
D.Protozoa

Answer 1

Hint: Most of the phylum is bilaterally symmetrical. In this type of symmetry, the opposite sides are similar to one another. For example Mollusca, sponge, Arthropoda, comb jellies.

Complete answer:
To answer this question we first need to understand that, in this world, every animal has its unique symmetry. According to their symmetry, they were divided into various types. There are three basic types of symmetry such as radial symmetry, bilateral symmetry, and asymmetry. But what is this symmetry and how are they classified? Radial symmetry is an asymmetry in which the sides exhibit corresponding parts around a central axis. Examples are starfish, sand dollar and sea urchins, etc. Bilateral symmetry means the opposite sides are similar, if we cut the animal from the center it gets divided into 2 equal halves. Humans are also bilaterally symmetrical. Examples of bilateral symmetries are flatworms, common worms (ribbon worms), clams, snail, spider, and sea star, etc. Note that asymmetry as the name suggests is unsymmetrical which means it lacks symmetry. If we cut them from the center they will not divide into two halves. Sponges from the Porifera phylum have asymmetrical body plans. Some animals start their life form with different symmetry in their younger stage and adult stage.
An example of this Echinodermata, during the larva phase, exhibits bilateral symmetry but in the adult, they develop radial symmetry. George Cuvier’s discovered symmetry in animals. He used symmetrical classification to classify animals. The radiates are the animals with radial symmetry, shaped one of the four parts of Georges Cuvier's characterization of the animal kingdom. Arthur Cayley, a Victorian mathematician was the first to show symmetries of an object. But he explains his symmetry on a mathematical structure.

Hence, the correct answer is option (A)

Note: We get to know that humans do not change their symmetry from childhood to their adult phase; they remain bilateral symmetrical. The bilateral symmetry starts from the phylum Platyhelminthes.