Question

Pectoral fin of fish and flipper of seal are examples of

• A. vestigial organ
• B. analogous organ
• C. homologous organ
• D. atavism

Answer 1

The correct option is B analogous organ

Analogous organs are the organs which have the same function and are superficially alike but are quite different in fundamental structure and embryonic origin.
The pectoral fins of fishes and the flippers of seals are flattened organs used for swimming. However, the two have different structure and origin. The flippers are the modified pentadactyl forelimbs whereas the fins are not pentadactyl.

Homologous organs are the organs which have a common origin and structural framework but perform different functions, e.g., hands of humans and wings of bats.

Vestigial organs are the ones which have become rudimentary and non-functional in the organism in the course of evolution but were functional and developed in the ancestral counterparts, e.g., vermiform appendix in humans.

Atavism is the reappearance of an ancestral genetic trait, that been lost through evolutionary change in previous generations, in the form of a modified biological structure, e.g., reappearance of a small tail in a human child.