Alternative Titles: American water shrew, Sorex palustrisLearn about this topic in these articles:Two of the 72 species in the genus Sorex are water shrews. The North American water shrew ( S. palustris) is found throughout much of the western United States and Canada, from the plains to the mountains. It is the smallest and least specialized species of water shrew, weighing up to 18 grams, with a body 6 to 9 cm long and a slightly shorter tail. It forages on...