Platypuses are found only in Australia. They are a part of a group of egg-laying mammals called monotremes.

Millions of years ago, there were a few species of reptile-like mammals. They had characteristics of today’s reptiles, birds, and mammals.

They had fur and nursed their babies like mammals. Their faces had bird beaks. Their skeletons were shaped like lizard skeletons. And like lizards and birds, they laid eggs. These species divided into three groups. Mammals. Birds. Reptiles. Over time, most egg-laying mammals died off. Today, only two remain: the platypus and the echidna.

What’s the first thing you notice about the platypus? It has the face of a duck. Yet, its bill is unlike any bird beak out there. It is flexible and spongy and has a smooth, suede-like skin. The bill is a super sensory organ, too, with nerve cells to sense pressure, movement, and electricity. It helps the platypus feel its way around the underwater world.

The bill has sensory receptors known as push rods. They are activated by pressure or touch. They are so sensitive that they can detect tiny movements in the water, as when insect larvae move just a few inches away.

The platypus bill has two more types of nerve receptors. They can detect tiny electrical signals made by the muscles in the bodies of their prey. So, even if a larva or shrimp are hiding, they don’t stand a chance.

Being waterproof and warm is vital for the platypus to survive. Even in cold winter, the platypus goes diving for food. It has a hairy adaptation for swimming in cold water. It is covered in thick, two-layered fur. This keeps body heat in and water out.

Fine hairs make up a woolly undercoat. On top of this is a second layer of longer hairs. Air is trapped between the layers. This keeps the animal warm and dry.