Question

Why do wool yielding animals have a thick coat of hair?

Answer 1

Sheep’s fleece is made of two types of hair:
(i) The outer coarse beard hair
(ii) The fine soft under-hair close to the skin.
Both of these hair form a dense layer of fur on the sheep's body that traps air.​ Air being a poor conductor of heat, does not allow heat to escape from the sheep’s body. Therefore this thick coat of hair keeps the body of the animal warm.