Instead, it is used as a stabiliser and to store fat. It does not use its tail to propel itself through the water. The platypus has a large flat tail covered in dense fur. It can retract the webbing on its feet, allowing it to walk on land and for dig its burrow. The animal paddles with its front limbs and uses its hind limbs for steering. The rear feet are partially webbed and are equipped with venomous spurs. The front feet are fully webbed and are like large paddles when extended. The platypus has four short dark brown limbs with broad clawed webbed feet. (Cats, birds and even crocodiles have this membrane.) It also has a third inner eyelid called a nictitating membrane, which acts like a squeegee and lubricates and removes dust and debris from the eye. These lids open when the animal is above water, revealing its eyes and ears, and closes when it is underwater, protecting them. Each groove acts like a pair of large eyelids. The duck-billed platypus's eyes and ears are located in grooves just behind its bill. Once detected, the platypus uses its bill to shovel up and unearth these creatures for it to eat. Electro-receptors on its bill are so sensitive that they can detect even the slightest movements made by underwater worms, insect larvae and crustaceans on which its feeds. Its nostrils are located on the top of its bill and close when the animal submerges. It is flat, soft, rubbery and looks like it's made of plastic. This keeps the animal's body warm and dry and gives it natural buoyancy when swimming underwater. The platypus's waterproof fur coat is double-layered and traps air for insulation. The underside has cream or greyish coloured fur. The platypus's upper body is covered in thick brown fur. The female is smaller in size than the male. Platypuses in the southern parts of Australia are larger than those found in the north.
![platypus drawing platypus drawing](http://getdrawings.com/images/platypus-drawing-6.png)
The platypus is about 35-50mm from head to tail and weighs between 0.5 to 3 kilograms.