Homologous and Analogous Organs
The organs which are similar in their anatomical structure and origin...
The phylogenetic history can be revealed by comparative study of external and internal structures.
The organs which are similar in their anatomical structure and origin [have common ancestry] but performs different functions are called homologous organs.
For example, the forelimbs of some animals like Whales, bats Cheetah and humans have similar anatomical structure i.e., humerus, radius, ulna, carpals, metacarpals and phalanges.
Some structures developed along different directions due to adaptations to different needs. This is called divergent evolution. Other examples include vertebrate hearts or brains. In plants thorns and tendrils of
bougainvillea and Cucurbita.
The organs which are different in anatomical structure and have different origin but perform similar functions are called analogous organs.
Different structures evolving for the same function and hence having similarity. This is called convergent evolution. For example, Wings of butterflies and birds.
Other examples include eye of octopus and mammals’, flippers of penguins and dolphins, sweet potato (root modification) and potato (stem modification).