According to Cat Health Detective, a cat's tail contains 19 to 28 vertebrae made of bone and cartilage. A human tailbone contains only four vertebrae. A cat's tail is important for maintaining balance.
The number of tailbones, or caudal vertebrae, varies from cat to cat. The tailless Manx cat, for example, has five vertebrae. Ten percent of a cat's 244 bones are in the tail. In the wild, big cats conceal their tails to avoid detection while hunting. However, a domestic cat's tail expresses its emotions. A quivering, upright tail signals extreme happiness. A whipping and twisting tail indicates displeasure.