Question

The adults are radially symmetrical but larvae exhibit bilateral symmetry in
A) Mollusca
B) Hemichordate
C) Echinodermata
D) Cephalochordata

Answer 1

Hint: Echinodermata are only found in the sea. They include sea stars, sea cucumbers, sea urchins, sand dollars, and brittle stars. There are no freshwater or terrestrial echinoderms recognized as of yet.

Complete answer:
Animals (also known as Metazoa) are multicellular eukaryotic organisms that comprise the Animalia biological kingdom. Animals, with a few exceptions, absorb organic material, breathe air, can travel, replicate sexually, and emerge from a hollow sphere of cells called the blastula during embryonic development. Animals can be classified based on their symmetry.

Sponges are often asymmetrical, which means that no plane that passes through the center divides them into equal parts.Radial symmetry occurs as every plane going through the central axis of the body splits the organism into two equal parts. This is the body plan of coelenterates, ctenophores, and echinoderms. Animals with bilateral symmetry include Annelids, Arthropods, and those whose bodies can be separated into equal left and right halves in just one plane.

Now let us look into the given options:
A) Because of torsion, molluscan larvae are bilaterally symmetrical, while adults are asymmetrical. As a result, it is incorrect.
B) In Hemichordata, both the larval and adult stages are bilaterally symmetrical. As a result, this is indeed incorrect.
C) Adult Echinodermata are radially symmetrical, while larvae are bilaterally symmetrical. Thus this the correct answer.
D) All adults and larvae of Cephalochordata are bilaterally symmetrical. As a result, this is wrong answer.

Echinoderms are marine mammal phylum. Adults are distinguished by their radial symmetry, which is shared by starfish, sea urchins, sand dollars, and sea cucumbers. They have five bodies, which they call tube feet. The larvae of echinoderms, on the other hand, have bilateral symmetry.

Thus the correct answer is option ‘C’

Note: Echinoderms are significant in both ecological and geological terms. Few other ecological groups are as widespread in the biotic desert of the deep sea, as well as shallower seas. Most echinoderms can replicate asexually and rebuild skin, muscles, and limbs; in some cases, total regeneration can occur from a single limb.