Akodon is a genus consisting of South American grass mice. Grass mice are found throughout South America, but the genus is
absent from the Amazon lowlands, west of the southern Andes, and from extreme southern South America. Akodon is one of the
most species-rich genera of Neotropical rodents. Species of Akodon are known to inhabit a variety of habitats from tropical
and tropical moist forests to altiplano and desert. Akodon is the largest genus in the tribe Akodontini.
Oryzomys is a genus of rodent distributed in North, Central and northern South America. They are part of a diverse tribe of
cricetid rodents known as rice rats (Oryzomyini). The genus name comes from the Latin Oryza, 'rice', and Greek mys (μῦς) 'mouse'.
Though the genus now contains only about six species, many more have previously been placed here, including members of genera
now considered unrelated to it, such as Thomasomys.
A cotton rat is any member of the Sigmodon genus of rodents. They are called cotton rats because they build their nests out
of cotton, and can damage cotton crops. Cotton rats have small ears and dark coats, and are found in North and South America.
They are primarily herbivores. The molars of cotton rats are S-shaped when viewed from above. The genus name literally means
S-tooth. Sigmodon hispidus was the first model organism to be used in polio research.
