What are vestigial organs ?(b) Write two names of some vestigial organs in human body.(c) Write the names of those animals in whom same organs are used ? Give two examples.

Answer:

(a) Vestigial organs are degenerated or underdeveloped, useless organs present in an organism, which were well developed and functional in its ancestors. They are an evidence of evolution.

(b) The vermiform appendix and the muscles of the ear pinna. (Also: tail bone (coccyx), wisdom teeth, nictitating membrane of the eye, body hair.)

(c) These organs are vestigial in human beings but functional in other animals:

• The appendix is fully functional (helps in digestion of cellulose) in ruminants and other herbivores such as the cow and the rabbit.
• The muscles of the ear pinna are functional in monkeys (and dogs, horses), which can move their ear pinna.

(The nictitating membrane, vestigial in man, is functional in birds and frogs, where it protects and cleans the eye.)