Lancelet

Lancelet fish (Branchiostoma) is sometimes called amphioxus, the type of the class Leptocardii, is a little creature, half and inch to four inches long. A lancelet may be regarded as a vertebrate reduced to its lowest terms. Instead of a jointed backbone, it has a cartilaginous notochord, running from the head to the tail. A nervous cord lies above it, enclosed in a membranous sheath. No skull is present and the nerve cord does not swell into a brain There are no eyes and no scles. The mouth is a vertical slit, without jaws. In this diagram we see the California lancelet twice the natural size, showing (g) gills, (l) liver, (m) mouth, (n) nerve cord, (nc) notochord.

Downloads