Cricetids

Cricetids, or Cricetidae, are a diverse family of small to medium-sized rodents that includes familiar groups such as hamsters, voles, lemmings, muskrats, and many New World rats and mice. With roughly 600 to 700 described species, Cricetidae is one of the largest rodent families, ranking after Muridae in global diversity. The family is distributed across many temperate and tropical regions and is absent only from Australia and Antarctica, with the greatest species richness in North America, Eurasia, Africa, and South America.

Taxonomy and diversity within Cricetidae are organized into several subfamilies, including Cricetinae (hamsters), Arvicolinae (voles, lemmings, muskrats), Neotominae (North American rats and mice), Sigmodontinae (South American rats and mice), and Nesomyinae (Madagascar’s native rats and mice). This classification reflects extensive evolutionary radiations in response to a range of habitats, from burrowing and grassland ecosystems to wetlands and forests.

Morphology and ecology are varied. Like most rodents, cricetids have a single pair of continuously growing incisors in each jaw, a diastema separating incisors from cheek teeth, and a generally adapted gnawing dentition. Their lifestyles range from fossorial or burrowing species to semi-aquatic forms such as the muskrat, as well as highly arboreal and terrestrial species. Diets are diverse, including seeds, grasses, roots, and in some species insects.

Humans interact with cricetids in various ways: several species are domesticated or kept as pets (for example, hamsters), while others are agricultural pests or serve as research models.