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 Exchange1 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.