The water deer (Hydropotes inermis) is a small deer superficially more similar to a musk deer than a true deer. Despite its lack of antlers and certain other anatomical anomalies—including a pair of prominent tusks (downward-pointing canine teeth), it is classified as a cervid. Its unique anatomical characteristics have caused it to be classified in its own genus (Hydropotes). Native to China and Korea, there are two subspecies: the Chinese water deer (Hydropotes inermis inermis) and the Korean water deer (Hydropotes inermis argyropus). Its prominent tusks have led to it being colloquially named the vampire deer in English-speaking areas to which it has been imported.Water deer are indigenous to the lower reaches of the Yangtze River, coastal Jiangsu province (Yancheng Coastal Wetlands), and islands of Zhejiang of east-central China, and in Korea, where the demilitarized zone has provided a protected habitat for a large number. They inhabit the land alongside rivers, where they are protected from sight by the tall reeds and rushes. They are also seen on mountains, swamps, grasslands, and even open cultivated fields. Water deer are proficient swimmers, and can swim several miles to reach remote river islands.
from : http://en.wikipedia.org/wiki/Water_deer