Males are larger than females.
Coloration is deep amber or blackish brown above and grayish white to yellowish chestnut below. This coat traps a layer of air in the kinks of the fibers of the underfur and between the underfur and the blades of the guard hairs and thus contributes substantially to the insulation of the body. The body of the platypus is streamlined and compressed dorsoventrally. The limbs are short and stout, and the webbed feet are broad. Each of the four feet has five clawed digits.