The Kingdom Animalia contains the animals, which are broadly categorized as invertebrates and vertebrates. The latter contains the familiar types such as mammals, amphibians, birds, fish, reptiles, which includes most domestic pets such as the ordinary house cat. While the former consists of those with or without an exoskeleton like the insects, crustaceans, jellyfish, worms, etc.
All members of Animalia are heterotrophic, multicellular eukaryotes. These are the principal characteristics that distinguish the animals from the other major kingdoms on Earth (plants, fungi, protists, or bacteria). The kingdom Animalia is very diverse group anatomically, reproductively, and ecologically, and contains millions of extinct and extant species.