Japanese water shrew

The Japanese water shrew (Chimarrogale platycephala), also called the flat-headed water shrew, is a special kind of mammal in the family Soricidae. This tiny creature lives near water and is very good at swimming. It can only be found on certain islands in Japan, like Honshu and Kyushu. Sadly, it is no longer seen in Shikoku.

In Japanese, it is called kawa nezumi, which means "river rat." These animals are very important for scientists because they help us learn about nature and how different kinds of animals live together. Even though they are small, they play a big role in keeping their homes healthy and balanced.

Description

The Japanese water shrew is a large shrew with a long tail, though the tail is shorter than its body. Its soft fur changes color with the seasons. In summer, its back and sides are grayish-black to gray, while its belly is a deep olive color. In winter, the back and sides turn blackish-brown and the belly becomes whitish. The fur has a shiny, silvery look because of special hairs on its back.

These shrews living on the island of Honshu are larger than those on Kyushu. Females there average about 12.5 cm (5 inches) in body length, while males are slightly larger at about 13.2 cm (5 inches). Their tails are about 9.8 cm to 10.3 cm (4 inches) long, and they weigh between 42.3 g (1 oz) for females and 49.3 g (2 oz) for males. Shrews on Kyushu are smaller, but there aren't many measured for accurate comparisons.

Distribution and habitat

The Japanese water shrew lives on the islands of Honshu and Kyushu, but has not been seen recently in Shikoku. These small animals prefer to stay in mountain streams, small rivers, and ponds. They like places with plenty of hiding spots, such as rocks, logs, and holes along riverbanks.

The area where a Japanese water shrew lives can be different for males and females, with females usually staying in areas about 300 meters long and males in areas up to 600 meters long. Fossils of these shrews have been found on both Honshu and Shikoku from times long ago, during the middle Pleistocene to the Holocene.

Diet

Japanese water shrews eat small water creatures like aquatic insects, crabs, shrimp, and tiny fish. They like to munch on caddisflies, mayflies, stoneflies, and dobsonflies. They also eat frogs, salamanders, snails, crayfish, earthworms, leeches, and spiders.

Behaviour

Japanese water shrews are good at swimming and diving. They have several periods of activity throughout the day. Sometimes, they may harm fish in fish-farming ponds.

Reproduction

There is not much known about how Japanese water shrews have babies or how long they carry their babies inside. But we do know they have two times of the year when they have babies: from February to June and again from October to December. On average, the mother carries between 1 and 6 babies at a time, with 4.2 being the usual number.

Scientists think these shrews can live for more than 3 years based on studying them in the wild.