All mammals are characterised by presence of mammary glands, hair on the body, presence of diaphragm, visceral gill clefts and dorsal nerve cord and seven cervical vertebrae. All mammals are not carnivorous. They include all type of individuals - herbivores, carnivores and omnivores. Moulting is usually seen in invertebrates. Presence of 7 cervical vertebrae in the neck is a common feature o f mammals.