Earless water rat

The earless water rat (Crossomys moncktoni) is a rodent of New Guinea, the only species in the genus Crossomys and part of the Hydromys group of Old World rats and mice (Murinae). It is among the most aquatically adapted rodents in the world, with extremely long, fully webbed hind feet, strongly reduced forelegs, very small eyes, absent or invisible external ears and a soft, waterproof coat that is greyish brown above and white below. Head and body length is 175 to 200 millimetres and the tail is longer, 212 to 260 millimetres. It lives at 1000 to 2700 metres in the Central Cordillera of Papua New Guinea, including the Huon Peninsula, in cold, fast-flowing mountain streams, hunting tadpoles, worms and river insects by day and sleeping in holes along the river bank at night. Oldfield Thomas described it in 1907 from a specimen collected by C. A. W. Monckton, and it remains a rather rare species. The IUCN Red List gives it the status least concern.