Why these South American rodents are named after the number eight

Nature · Published 3 October 2026 Swipe more like this →

In short: The genus Octodon, native to the Chilean Andes, earns its name from a peculiar anatomical feature. Their molars and premolars are shaped precisely like the digit eight. These social, burrowing rodents are more than just a dental curiosity; they are highly adaptable survivors in diverse mountain environments.

First described by British zoologist Edward Turner Bennett in 1832, the Octodon genus comprises five distinct species primarily endemic to the mountains of Chile. While the common degu, O. degus, is frequently kept as a pet globally, its wild relatives inhabit a range of altitudes spanning from sea level up to 1,800 meters. These medium-sized rodents are defined by their grayish, orange-highlighted coats and tails that can reach up to 170 millimeters in length.

The survival strategy of the Octodon is rooted in both social behavior and biological efficiency. They live in complex, multi-tunnel burrow systems in groups containing both males and females. When food is scarce, they engage in coprophagia, consuming their own droppings. This process allows them to extract additional nutrients through microbial fermentation in the cecum, effectively optimizing the digestion of fibrous vegetation. While primarily folivorous herbivores, their activity patterns are flexible, with some species being nocturnal and others diurnal.

Conservation status varies significantly across the genus. While the common degu and O. lunatus are classified as species of least concern, others face severe threats. O. pacificus, found exclusively on Mocha Island, is considered critically endangered. Meanwhile, O. bridgesii is listed as vulnerable, though it is sometimes considered conspecific with O. ricardojeda, a species found in both Chile and the Argentine province of Neuquén. Understanding these rodents requires looking beyond their pet-store popularity to the fragile, high-altitude ecosystems they call home.

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