The marsh shrew (Sorex bendirii), also known as the Pacific Water Shrew, is a large North American shrew. It is found near aquatic habitats. It is the largest member of genus Sorex in North America.
It is dark brown in color with a dark belly and a long tail. Its hind feet have coarse hairs on the toes. Its body is about 6.30 in (16 cm) long including a 2.76 in (7 cm) long tail. It weighs about .46 oz (13 g).
This animal is found along the Pacific coast of southern British Columbia and the western United States.
It swims and takes short dives in search of food. Its diet includes earthworms, aquatic insects, slugs and snails.
This animal is active during the day but is more active at night. The female has a litter of 3 or 4 young. They have the young in a nest, in a tunnel, or under a log. Water shrews typically live about 18 months.
The range and numbers of these animals are thought to have declined due to loss of suitable wetland habitat. They have declined especially near urban areas and farmlands.