Many of the rodent species have cheek pouches, which is used for the storing of food and nesting material. Some rodents have external cheek pouches and others have internal cheek pouches, the hamster for instance has internal cheek pouches. The pouches are very substantial often allowing for a huge quantity of contents and reaching past the shoulder when full to capacity – manipulating from behind with the hand will then empty the pouches.
The largest rodent is the capybara but many rodents are comparatively small mammals such as the hamster, rat and mouse.
All rodents are plantigrade (they place the full length of their foot, including podials and metapodials, on the ground during each stride) although the faster ones are able to lift up onto their digits. The sole of their feet are usually bare. The characteristic rodents have short limbs, showing 4 or 5 digits on each hand and 3 to 5 digits on their feet. In addition to the plantigrade rodents there are others such as the saltatorial rodents (hoppers). Most rodents use their hands as actual hands, although there is no thumb but the controlling capability is good.
Some rodents live in trees (arboreal), some live under the ground in tunnels and some live in and out of water and of course many rodents are able to exist effortlessly in close contact with humans.
A rodents diet is very varied but most are in actual fact herbivores (plant eaters only) and most eat seeds. You will find that many species eat insects and bugs and some rodents are omnivores (obtaining food from plants and animals).
To a greater or lesser degree most rodents are herbivores, therefore it is important that they have a digestive system that can manage the almost hard to digest cellulose of plants.