- Even though otters are considered land mammals, they spend a lot of their time in the water and are specially adapted to fishing in cold northern waters. Their fur is water repellant to help keep them warm.
- They can close their nostrils and ears when swimming or diving.
- They can hold their breath for up to eight minutes.
- Babies are helpless when born and keep their eyes closed for three to four weeks.
- They do not build their own dens, but rather take dens leftover from other animals.
- They can re-breathe air bubbles when under the ice.
Most of North America, except deserts and plains
Lakes, rivers, swamps, marshes, and estuaries
4 feet long, between 11-35 pounds
Primarily fishes, but may consume insects, crayfish, frogs, snakes, lizards, smaller mammals, and small water birds
Because these otters are semi-aquatic, they have streamlined bodies with thick tapered tails and short legs. They also have wide, rounded heads, small ears, nostrils that can be closed underwater, long thick whiskers, and partially webbed feet. The fur of the otter is dark brown on the back and light to golden brown on the belly and cheeks. They have short, dense fur with a layer of insulating fat underneath.
Though a usually social animal, river otters are mildly territorial and generally practice mutual avoidance. Males often have larger home ranges than females. They have been known to build dens in the burrows of other mammals. These dens are commonly found along riverbanks or under a pile of rocks or logs. These otter residences feature numerous tunnels, one of which usually allows them to come and go from under the water. Tunnels will lead to an internal nest chamber which is lined with organic materials such as leaves, moss, tree bark, or hair.
The babies are helpless at birth, much like human babies. Their eyes are closed and they’re covered with a light coat of fur. After three to four weeks they open their eyes and begin to play soon after. Male otters do not help raise the baby otters. Females rear the young and teach them how to swim by shoving them into the water. River otters are natural swimmers, and with the help of their mother (mostly supervision) they soon get the hang of it. Juvenile otters stay with their mothers until she gives birth again the next year.