Summary
The characteristic features of Chordata are a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail. Chordata contains two clades of invertebrates: Urochordata (tunicates) and Cephalochordata (lancelets), together with the vertebrates in Vertebrata. Most tunicates live on the ocean floor and are suspension feeders. Lancelets are suspension feeders that feed on phytoplankton and other microorganisms. Vertebrata is named for the vertebral column, which is a feature of almost all members of this clade.
Glossary
Cephalochordata
chordate clade whose members possess a notochord, dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail in the adult stage
Chordata
phylum of animals distinguished by their possession of a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail at some point during their development
Craniata
clade composed of chordates that possess a cranium; includes Vertebrata together with hagfishes
cranium
bony, cartilaginous, or fibrous structure surrounding the brain, jaw, and facial bones
dorsal hollow nerve cord
hollow, tubular structure derived from ectoderm, which is located dorsal to the notochord in chordates
lancelet
member of Cephalochordata; named for its blade-like shape
notochord
flexible, rod-shaped support structure that is found in the embryonic stage of all chordates and in the adult stage of some chordates
pharyngeal slit
opening in the pharynx
post-anal tail
muscular, posterior elongation of the body extending beyond the anus in chordates
tetrapod
phylogenetic reference to an organism with a four-footed evolutionary history; includes amphibians, reptiles, birds, and mammals
tunicate
sessile chordate that is a member of Urochordata
Urochordata
clade composed of tunicates
vertebral column
series of separate bones joined together as a backbone
Vertebrata
members of the phylum Chordata that possess a backbone