Amphioxus, << `am` fee AHK suhs, >> also called lancelet, << LANS liht, >> is a group of small sea animals that live in shallow water. Amphioxus is a link between vertebrates and invertebrates—that is, animals with backbones and animals without backbones. It has no distinct brain, but it has a nerve cord running along its back that is somewhat like the spinal cord of vertebrates. Instead of the hard, jointed backbone of the vertebrates, the amphioxus has an organ called the notochord. This is a fairly stiff rod of cartilage, found along the back just under the nerve cord. This primitive form of backbone makes the amphioxus more like a vertebrate than an invertebrate.
