This has been noted as insignificant though because they do not grab for their food. The rabbit's nose has slit-like nostrils which can be opened and closed by a fold of skin. This movement looks like they are winking their noses. Their smell is not highly developed, but their sense of hearing is very good. They possess weak but flexible necks which allow them to turn their heads more.
Cottontails have only one external opening for both anus and urethra, called the cloaca.
They are special in that nearly half of their fibula is fused with the tibia. This allows them to have great mobility and to run faster. They have a narrow, light skull with pronounced internal segmentation. The palatal openings of their skull are only as wide as the molar teeth. The ulna and the radius are of equal thickness and upper and lower arms are almost the same length.