Peter Rabbit , his sisters Flopsy , Mopsy , and Cottontail , and his mother are anthropomorphic rabbits . They dress in human clothing and usually walk standing up . Peter Rabbit , his sisters Flopsy , Mopsy , and Cottontail , and his mother are anthropomorphic rabbits who dress in human clothing and generally walk upright on their hind legs , though they live in a rabbit hole under a fir-tree .