This aquatic animal, found mostly in Australia, has a bill like a duck, dense fur, webbed feet, and a broad flattened tail. What kind of animal is this?

This remarkable creature from eastern Australia is a collection of features that seem borrowed from various other animals. Its most famous characteristic is the soft, rubbery bill, which resembles that of a duck but is equipped with thousands of receptors that can detect the weak electrical fields of its prey underwater. Combined with dense, waterproof fur like an otter's, a broad, flat tail similar to a beaver's, and webbed front feet, it is perfectly suited for its semi-aquatic lifestyle in rivers and streams. When first encountered by European scientists, its bizarre appearance led many to believe it was an elaborate hoax, a creature stitched together from different animals.

The platypus is a monotreme, a unique order of mammals that lay eggs instead of giving birth to live young. It is one of only five such species in the world, the others being four species of echidna. This ancient lineage of mammals possesses a mix of mammalian, reptilian, and avian characteristics in its DNA. Adding to its strangeness, the male platypus is one of the few venomous mammals. It has a sharp spur on each hind leg capable of delivering a venom that is excruciatingly painful to humans. Females, on the other hand, nurse their hatched young, known as puggles, but do so without nipples; instead, they secrete milk onto their abdominal skin for the babies to lap up.