Keeper - 

An employee in a zoo who takes care of the animals.

Keratin - 

A protein that hair, nails, skin, and hornsGrowths on the head of an antelope, cow, sheep, or goat that are never shed. are made of.

Knuckle walk - 

A way of walking that some great apes use to get around. They curl up their fingers and use the knuckles of their hands as feet. Gorillas, orangutans, and chimpanzees often use this method to walk across the ground.