The coloration of a platypus can vary, depending on factors such as age, sex, and habitat. Generally, platypuses have a dark brown or blackish-brown fur on their back, while their underbelly is lighter, ranging from cream to light brown. This contrast in coloration helps with camouflage, as the darker fur blends with the water when viewed from above, and the lighter fur matches the sunlight filtering through the water from below. This provides them with effective camouflage while swimming.