Question

Explain the terms analogous and homologous organs with examples.

Answer 1

Hint: The human body is made up of several organs. They may be structurally similar or functionally different from other animals. Analogous and homologous organs are used as evidence of evolution.

Complete answer:
- Homologous organs can be defined as the organs of different animals that have a similar structure but differ in their functions. The structure of the two different animals resemble but the functions of their organs vary. Homologous structures share a similarity in terms of their morphology, genetics, anatomy, embryology, may or may not have similar function but have the same origin and hence called homologous organs. Some of the examples of homologous organs are the forelimbs of frog, man, and the flippers of the whale.
- It can be observed that the structure of these animals is the same but they differ functionally. The flippers are used for swimming, the forelimbs of frogs are used for jumping and propping, and the forelimbs of man are used for writing, eating, holding things, etc. Similarity in the structures suggests that all these animals have a common ancestor.
- Analogous organs can be defined as the organs of different animals that are structurally different but perform the same functions. The analogous structures look similar superficially and are dissimilar anatomically but do the similar functions are called analogous structures. Some of the examples of the analogous organ are the wings of the insect and the wings of the bird.
- It can be observed that the structure of wings of the bird has bones covered by flesh, skin, and feathers. Whereas the wings of an insect is an extension of the integument. But in both cases, the wings are used for flying. These organisms would have to adapt to the same ecological niche as other organisms. Hence, they may have evolved similar (analogous) organs.

Note: It is to be noted that some organs are present in our body which are called vestigial organs are organs, as they are no more functional the way they were in their ancestral form of the trait. It is very important that one does not get confused between homologous and analogous structures.
Homologous - Same ancestor, different function
Analogous - Different ancestor, same function