BIO 101 Lecture Notes - Lecture 25: Dorsal Nerve Cord, Anglerfish, Swim Bladder
Document Summary
Humans are members of a taxonomic group known as the chordates (chordata) All chordates have deuterostome development (characteristic of the echinoderms) There are four other features, possessed by all chordates during some stage of their lives: a dorsal nerve cord, a notochord, pharyngeal gill slits, a post-anal tail. The hollow nerve cord of chordates lies above the digestive tract, running lengthwise along the dorsal (upper) portion of the body. The center of the nerve cord is filled with fluid. The nerve cord develops a thickening at its anterior end that becomes a brain. The notochord extends along the length of the body, between the digestive tract and the nerve cord. The notochord is present during early stages of development and disappears as a skeleton develops. Pharyngeal gill slits are located in the pharynx (the cavity behind the mouth) In some chordates the slits form functional openings for gills (organs for gas exchange in water)