Nutria
A semiaquatic rodent native to South America, introduced worldwide.
The nutria (Myocastor coypus) is a large, herbivorous, semiaquatic rodent native to subtropical and temperate South America. It lives in burrows alongside water, feeds on aquatic and riparian vegetation, and contributes to wetland food webs and the dispersal of aquatic plants and spores. Introduced to North America, Europe, and Asia primarily by fur farmers, it is considered invasive in several countries due to damage to wetland vegetation and infrastructure.
- Scientific name
- Myocastor coypus
- Native range
- Subtropical and temperate South America
- Weight
- 4–9 kg (9–20 lb) on average; up to 16–17 kg
- Body length
- 40–60 cm (16–24 in)
- Tail length
- 30–45 cm (12–18 in)
- Lifespan
- Up to 6 years in captivity; rarely past 3 in the wild
- Gestation
- 130 days
Lore & Background
The nutria was first described by Juan Ignacio Molina in 1782 as Mus coypus. The genus Myocastor was assigned by Robert Kerr in 1792. Four subspecies are generally recognized: M. c. bonariensis, M. c. coypus, M. c. melanops, and M. c. santacruzae. The subspecies M. c. bonariensis, from the northernmost subtropical part of the range, is believed to be the type most commonly introduced to other continents. Phylogenetic analysis places Myocastor as the sister group to Callistomys (painted tree-rats), within the Myocastorini tribe.
Reader's Guide
The nutria is significant both as a native component of South American wetland ecosystems and as an invasive species elsewhere. In its native range, it acts as a large semiaquatic herbivore, consuming aquatic and riparian vegetation and dispersing plant propagules through endozoochory. A 2024 study estimated an individual coypu dispersed about 691 propagules per day, including fern spores. However, introduced populations can damage wetland vegetation and infrastructure through feeding and burrowing, leading to its classification as invasive in several countries. Some populations carry zoonotic pathogens like pathogenic Leptospira, though their epidemiological significance is scarce and region-specific. The nutria is still hunted and trapped for its fur in some regions.
Did You Know?
- The genus name Myocastor literally means 'mouse-beaver' from Ancient Greek.
- Nutrias have bright orange-yellow incisors due to iron pigment in the tooth enamel.
- Female nutrias have mammary glands high on their flanks so young can nurse while the female is in the water.
- Baby nutrias are precocial, born fully furred with open eyes, and can swim within hours of birth.
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