a small aquatic, egg-laying monotreme of Australia and Tasmania, having webbed feet, a tail like that of a beaver, a sensitive bill resembling that of a duck, and, in adult males, venom-injecting spurs on the ankles of the hind limbs, used primarily for fighting with other males during the breeding season, tumepruun ainupiluliste seltsi kuuluv poolveelise eluviisiga ürgimetaja, nokkloomlaste (Ornithorhynchidae) sgk-a ainus liik. Elutseb Kagu-Austraalia ja Tasmaania jõgede kaldaurgudes ... pardinokataolist (sellest nimetus) koonu katab sarvestunud nahk; viie varbaga jäsemetel on ujunahad. Toitub selgrootuist. Sigib munadega, poegi on kuni 3, toidab neid piimaga ...