The main difference between vertebrates and invertebrates is that vertebrates have backbones as part of their endoskeletons, whereas the anatomy of invertebrates lacks this feature. Another difference is that vertebrates all belong to the phylum Chordata and the subphylum Verdata, while invertebrates represent a more diverse group of animals that belong to several different phyla.
Examples of invertebrates include comb jellies, belonging to the phylum Ctenophora, sponges, belonging to the phylum Porifera, molluscs of the phylum Mollusca, and flatworms of the phylum Platyhelminthes. Sea anemones, corals and jellyfish, all belonging to the phylum Cnidaria, are also invertebrates. There are almost 1 million known species of invertebrates as of 2015, and scientists believe there may be as many as 30 million living invertebrate species. The vast majority of living animals are invertebrates, representing over 97 percent of animal species.
Because vertebrates all belong to the same phylum, they all share several traits that are characteristic of phylum Chordata in general. These include a complete digestive system, a closed blood system, bilateral symmetry, a ventral heart and a tail at some point in their development. All chordates have endoskeletons, but there are some that lack backbones, called invertebrate chordates. Some classes of vertebrates include birds, mammals, jawless and armored fish, reptiles and amphibians.