Two covered with hair. Two covered with feathers.

What do we call the covering of a sheep? Of a pig? Of what use is hair to animals?

What covering has an oyster? A lobster? A turtle? Of what use is it to them?

The duck's feathers are covered with an oily coating, which keeps them from getting wet. Are the feathers of the hen so covered? Why?

Suppose a squirrel's covering were like that of a turtle's, what would result?

What would result if a bird had scales instead of feathers? You see that each animal has that covering which suits its habits best.