Rodent. Brown in color, but can range from reddish to blackish depending on the subspecies. Distinct short tail with that compared to other beavers. Thought to be physiologically restricted to temperate rainforests as arid locations lack sufficient water resources - and they are unable to produce concentrated urine. They have an unusual projection on each molar and premolar that is unique among mammals - and as with most rodents their teeth are ever-growing.