Pearson's Tuco-tuco

Fascinating facts about the Pearson's Tuco-tuco

• Below 200 m elevation, this tiny rodent is found nowhere but Uruguay, turning the entire country into its exclusive backyard and highlighting how a whole nation can host a species you’ll never see outside its borders.
• A single burrow sports on average 13 separate openings, each leading to one or two nests stitched from dried grass, an underground apartment complex that lets the animal escape predators and the harsh sun without ever surfacing.
• Scientists have counted at least three distinct chromosome sets in the population: 2n = 68–70 with a fundamental number of 80–88, and a separate 2n = 56 with FN = 77–79, a puzzle that suggests we may actually be looking at several hidden species.
• Even its close cousin, C. dorbignyi, shares an identical 2n = 70 karyotype, meaning the two look the same under the microscope even though they live apart, challenging how we define species by DNA alone.
• Named for American zoologist Oliver Payne Pearson, this critter’s fate now hangs on the spread of farms and towns that turn its sandy-soil homes into fields, a reminder that even the most adaptable underground dwellers can be erased by human development.

At a glance

About the Pearson's Tuco-tuco

Pearson's tuco-tuco (Ctenomys pearsoni) is a rodent endemic to Uruguay, found at elevations below 200 m. It constructs burrows with multiple openings (an average of 13) containing one to two nests of dried grass, prefers sandy soil but is somewhat adaptable, and is threatened by loss of habitat to development, agriculture and ranching. Multiple karyotypes have been reported, including 2n = 68–70 with FN = 80–88 and 2n = 56 with FN = 77–79, suggesting the taxon may represent several species. The species is named after American zoologist Oliver Payne Pearson.

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