The nutria, also known as the coypu, is a large semi-aquatic rodent that looks somewhat like a giant beaver or a very large rat. This mammal is native to South America, where it naturally inhabits freshwater ecosystems. Following its introduction to North America and other continents, primarily through the fur trade, the nutria established wild populations and is now a widespread species outside its native range.
Measuring the Nutria
The nutria is one of the world’s larger living rodents, with a total length spanning up to three-and-a-half feet from nose to tail tip. An adult nutria typically measures about 24 inches in body length, excluding the tail, which adds another 12 to 18 inches. The weight of an adult generally falls between 12 and 20 pounds, though some mature individuals can reach a maximum of 37 pounds. The nutria’s tail is a distinguishing feature, being round in cross-section and sparsely covered with fine hair, giving it a rat-like appearance. In contrast, a beaver’s tail is flat and paddle-shaped, and a muskrat’s is laterally flattened. The nutria is larger than a muskrat but smaller than a beaver, helping observers distinguish between the three semi-aquatic rodents.
Distinctive Physical Characteristics
The nutria possesses several unique traits adapted to its watery habitat. The most striking feature is its large, prominent incisor teeth, which are a deep, bright orange or reddish-yellow color. This coloration is due to iron pigments in the tooth enamel, making the enamel very hard and durable for gnawing on tough vegetation.
The nutria’s hind feet are partially webbed, with four of the five toes connected by skin, making the nutria a highly efficient swimmer. The front feet are not webbed and are used for handling food and grooming. To aid in swimming and foraging, the nutria’s small eyes, ears, and nostrils are set high on its head. This placement allows the animal to remain almost entirely submerged while keeping its sensory organs above the waterline. The nutria has two layers of fur: a dense, gray undercoat and a layer of long, coarse guard hairs that vary from yellowish-brown to dark brown. Glands near the corners of its mouth secrete oils that the rodent uses to groom and waterproof the fur.
Where Nutria Live and What They Eat
Nutria are highly adaptable but generally live near permanent bodies of water, including freshwater marshes, swamps, ponds, and slow-moving rivers. They can also inhabit areas with brackish water, such as coastal marshes. These rodents build their homes by excavating burrows into the banks of water bodies, with the main chamber situated above the water line.
The nutria’s diet consists primarily of aquatic and semi-aquatic vegetation, making it an herbivore. They consume a wide variety of plant material, including the roots, rhizomes, and tubers of species like cattails, cordgrasses, and rushes. The animal can consume up to 25% of its body weight in vegetation each day. When foraging, nutria often dig through the soil to reach the most nutritious root systems. They may also construct floating platforms out of cut vegetation to use as feeding and resting sites while in the water.