In zoology, neozoa are animal species that are non-native to a geographical region, and were introduced in recent history. The term is derived from the Greek neo = new and zoa = animals/organisms. Animal species are defined as neozoa if they have been introduced after 1492, when Christopher Columbus arrived in the New World and the Columbian Exchange 1 began.
Animals are further divided in vertebrates and Invertebrates:
- Vertebrates make up about 4% of all described animal species; the rest are invertebrates, which lack vertebral columns. Vertebrates include the jawless fish and the jawed vertebrates, which includes the cartilaginous fish (sharks and rays) and the bony fish. A bony fish clade known as the lobe-finned fishes is included with tetrapods, which are further divided into amphibians, reptiles, mammals, and birds.
- Invertebrates are animals that neither possess nor develop a vertebral column. This includes all animals apart from the subphylum Vertebrata. Familiar examples of invertebrates include insects, crabs, lobsters and their kin, snails, clams, octopuses and their kin, starfish, sea-urchins and their kin, and worms. The majority of animal species are invertebrates.