Mammals
Coypu
Myocastor coypus · also called nutria
Gnawing through tough marsh vegetation with bright orange front teeth, a coypu paddles along a quiet waterway, a semi-aquatic rodent whose native South American population remains entirely stable even as fur-trade releases have turned it into a damaging invasive species across three other continents.
Overview
The coypu, Myocastor coypus, also widely known as nutria, is a large, semi-aquatic rodent native to wetland and grassland habitat across temperate regions of South America. Its distinctive iron-stained orange teeth, webbed hind feet suited to swimming, and dramatic transformation into a globally damaging invasive species make it one of the more ecologically consequential rodents found anywhere in the world.
A native success story turned global problem
Perfectly at home in its native South American wetlands, the coypu’s story took a sharp turn once the fur trade spread it across other continents, where escaped and released animals have gone on to reshape wetland ecosystems far from where the species naturally belongs.
Status
Least Concern in its native South American range, despite having become a significant invasive species across parts of North America, Europe, and Asia.
Coypu: common questions
Why does the coypu have orange teeth?
This species has bright orange front incisors, a colouration caused by iron compounds within the tooth enamel, which also helps strengthen the teeth for gnawing through tough aquatic and marsh vegetation as part of its regular diet.
Why did the coypu become invasive in so many countries?
This species was widely farmed for its fur under the name nutria, and escapes and deliberate releases from fur farms established damaging invasive populations across parts of North America, Europe, and Asia, where it now causes significant harm to wetland ecosystems.
How does the coypu damage the environments it invades?
This species can cause significant damage to wetland vegetation and burrow into levees and riverbanks in areas where it has become invasive, altering habitat structure in ways that can harm native plant and animal communities that depend on more stable wetland conditions.
How can you tell a coypu from a beaver or muskrat?
This species has a large, robust body considerably bigger than a muskrat, with a rounded, sparsely furred tail quite different from the flattened, paddle-like tail of a true beaver, making tail shape one of the clearest ways to distinguish between the three semi-aquatic rodents.