Muskrats are common semi-aquatic mammals found throughout North America. Their scientific classification often causes confusion, with many wondering if they are related to rats or beavers. Understanding the biological characteristics of rodents clarifies the muskrat’s place in the animal kingdom.
Defining Rodents
Rodents are a diverse group of mammals belonging to the order Rodentia. A defining characteristic of all rodents is their unique dental structure: a single pair of continuously growing incisors in both their upper and lower jaws.
These incisors have a thick layer of enamel on the front and softer dentine on the back, creating a self-sharpening, chisel-like edge as they wear. Rodents must constantly gnaw to prevent these incisors from growing too long. Familiar examples of true rodents include mice, rats, squirrels, beavers, hamsters, and guinea pigs.
Characteristics of Muskrats
Muskrats, scientifically known as Ondatra zibethicus, are medium-sized semi-aquatic mammals native to North America. Adults typically weigh between 0.6 and 2 kilograms (1.25 to 4.5 pounds) and have a body length, excluding the tail, of 20 to 35 centimeters (8 to 14 inches).
Their fur is short and thick, ranging from medium to dark brown, with a slightly lighter underside. This fur has two layers, providing effective insulation and buoyancy in water. A distinctive feature is their long tail, which measures 7 to 12 inches (18 to 30 centimeters) and is covered in scales rather than hair. This tail is flattened vertically, aiding in steering while swimming. Their partially webbed hind feet serve as their primary means of propulsion in aquatic environments.
Muskrats inhabit various wetlands, including marshes, ponds, rivers, lakes, and canals. They construct bank burrows with underwater entrances or build dome-shaped lodges from vegetation. Their diet consists mainly of aquatic plants like cattails and water lilies, though they also consume small animals such as mussels, frogs, and fish. They can even chew underwater due to specialized lips that close behind their incisors.
Muskrat Classification Explained
Muskrats are indeed rodents. Their scientific classification places them firmly within the order Rodentia. Specifically, muskrats belong to the family Cricetidae and the subfamily Arvicolinae. This subfamily also includes many species of voles and lemmings, making muskrats their closest relatives. The muskrat stands as the largest species within the Arvicolinae subfamily.
Confusion often arises because muskrats are frequently mistaken for beavers. Significant differences exist between these two semi-aquatic rodents. Muskrats are considerably smaller, weighing between 0.6 and 2 kilograms, whereas beavers can weigh 14 to 40 kilograms or more.
Their tails also differ distinctly: the muskrat’s tail is vertically flattened and scaly, while a beaver’s tail is wide, horizontally flattened, and paddle-shaped. Furthermore, beavers are known for building dams and felling trees, behaviors not exhibited by muskrats. While muskrats are often called “rats” in a general sense due to their size and adaptable nature, they are not “true rats” from the genus Rattus.