Chordates have bilateral symmetry, which means that the left side of their bodies are symmetrical to the right side, and vice versa. All chordates are monophytic, meaning that they share a single common ancestor. Chordates also have a tail for at least part of their lifespan.
The phylum Chordata includes at least 65,000 living species, including bony fish, amphibians, reptiles, birds and mammals, including humans. Chordates are distinguished by their dorsal neural tubes, which form into the spinal cord in vertebrate chordates, their pharynxes or gills used for breathing or filter feeding in some cases, and the cartilageous notocord, which forms the spinal column.