Members of this phylum, our own, are the best known of all the animals. In fact, in the minds of many people, chordate is synonymous with animal. All mammals, birds, amphibians, reptiles, and fish (that is, the vertebrates), along with several obscure groups of animals (including some invertebrates), belong to this phylum. There are about 45,000 species, including all the animals of major economic importance, with perhaps the exception of some arthropods and mollusks.