North American river otter

The North American river otter (Lontra canadensis), also known as the North American otter or northern river otter is a species of semiaquatic mustelid found in Canada and the United States found in waterways and coasts. It is equally versatile to both land and water. It is protected by its brown or black thick, water-repellent fur, with the throat, chin, and lips are grayer than the rest of its body. Fur of senescent otters may become white-tipped and rare albinos may occur. It is a member of the otter subfamily, Lutrinae which is part of the weasel family (Mustelidae). It makes a burrow near close to the water's edge in a river, lake, swamp, estuary, coastal shoreline, or tidal flat. The den usually has many tunnel openings, one of which generally allows the otter to enter and exit. Female river otters give birth in these burrows, producing litters of 1 to 6 young.

North American river otters prey on readily accessible species, such as many kinds of fish (mainly perch, suckers, and catfish), freshwater clams, amphibians, mussels, snails, small turtles, and crayfish. Instances of North American river otters eating birds and small mammals have been reported as well. The North American river otter weighs 5 to 14 kg, with short legs, an elongated body and a muscular neck. Like all other otter species, they have long bodies, and long whiskers that are used to enhance sensory on land and water and to detect prey in dark waters. The average weight of an adult male is 11.3 kg while an average weight of a female is 8.3 kilograms. North American river otters are also sexually dimorphic, with males on average being 5% larger than females. The body length ranges from 66 to 107 cm. At least one third of the river otters total body weight consists of its long, tapered tail, with it ranging 30 to 50 cm. The fur is short, with average on guard hairs being 23.8 mm, with a density on about 57,800 hairs.

A broad muzzle is found on the river otters flat head, and the ears are round and inconspicuous. It has a relatively flat skull, which is defined by a short, broad rostrum for exhaling and a long broad cranium. Its rhinarium is bare with an obtuse triangular projection and has rather small eyes. When underwater, the ears and nostrils close to prevent water from getting into them. In the wild, they normally live up to 8 to 9 years, but are capable of living at 13 years. In captivity, they live in 21 years of age on average, but can reach to 25 years of age.