The family Ornithorhynchidae consists of monotremes, a unique group of egg-laying mammals, represented solely by the platypus (Ornithorhynchus anatinus). Native to eastern Australia and Tasmania, platypuses are semi-aquatic, spending much of their time in freshwater rivers and streams. They have a distinctive duck-like bill, webbed feet, and a flat tail, adaptations suited for swimming and foraging for invertebrates in the water. Remarkably, they are one of the few venomous mammals, with males possessing spurs capable of delivering a painful venom. Ornithorhynchids also display unusual reproductive traits, laying eggs rather than giving live birth, and they produce milk without nipples, secreting it through mammary gland openings on the skin. This family represents an evolutionary bridge between reptiles and mammals, exhibiting a blend of primitive and highly specialized features.