Why do animals moult?

Creatures throughout the animal kingdom undergo the process of moulting – the replacement of their horns, hair, skin or feathers. Insects moult to allow their growing bodies to expand beyond the constraints of their rigid exoskeleton, forming a new shell in the process and often eating the old one. Most mammals shed their hair in autumn to grow a thicker layer of protection for the winter, and vice versa for the summer.

Birds moult their feathers regularly as they become worn with use, growing fresh new ones in their place. Water birds, however, often lose all their feathers at once and thus the ability to fly, meaning that they must remain hidden from predators until their feathers have re-grown.

Camouflaged animals keep their pattern when they’re moulting except for decorator crabs, who transfer the camouflage from their old to new exoskeleton.