Octodonts are similar in appearance and size to gerbils and rats. They have stocky bodies, large heads, pointed noses, and medium-sized rounded ears. Octodonts have rear legs that are slightly shorter than their front legs. They have four clawed toes on their front paws and five on their back paws.
Octodonts have a head and body length of 5 to 8.7 inches (125 to 221 millimeters) and a tail length of 1.5 to seven inches (40 to 180 millimeters). Their weight ranges from 2.8 to 10.6 ounces (80 to 300 grams). They have long, dense, silky fur that is yellow, brown, or gray on their upper bodies and white or cream on their underside. One exception is the coruro, which is almost entirely black.
Octodonts are found in southwest Peru, Chile, Argentina, and southwest Bolivia.
The octodont habitat ranges from coastal scrub brush to barren rocky outcroppings in mountains. They are found in desert, deciduous forest, grassland, and foothills.
Octodonts are herbivores, meaning they eat only plants. All but one species eat mainly at night. The degu feeds during the early morning and early evening. Most species eat a diet of grass, leaves, herbs, bark, and seeds. The coruro feeds mostly on underground portions of plants.
BEHAVIOR AND REPRODUCTION
All but one species of octodont are nocturnal, meaning they are most active at night. Degus are diurnal, meaning they are most active during daylight hours.
Octodonts are extremely talented and organized diggers. They build burrows consisting of many branched tunnels and multiple entrances. When digging a burrow, the adults form a chain that speeds up the activity. Most octodonts, such as degus, coruros, and rock rats exhibit a complex system of social behavior, living in colonies of five to ten adults and their young. They groom each other, lay bunched together when sleeping, and the females nurse each other’s babies. Other species of octodonts are solitary.
The mating system for octodonts is not well understood although in several species it appears to involve courtship rituals. Most species, including the degu and coruro, usually breed twice a year. Females reach puberty, the age of sexual maturity at which they can bear offspring, at six months. The gestation period, the amount of time the young are carried in their mother’s womb, is seventy-seven to 105 days. Litters usually consist of four to nine babies.
OCTODONTS AND PEOPLE
Most octodonts have little interaction with humans. Degus are used for laboratory research. They are also sold as pets in the United States. In the wild, degus and coruros are often killed by farmers who consider them agricultural pests, blaming them for destroying grain fields, orchards, and vineyards.
The Mocha Island degu is listed by the World Conservation Union (IUCN) as Vulnerable, facing a high risk of extinction, due to their small distribution area. The plains viscacha rat is listed as Vulnerable due to a loss of at least 20 percent of its population within ten years. Other species are not listed by IUCN.