deoxyribonucleic acid, desoxyribonucleic acid, DNA(noun) (biochemistry) a long linear polymer found in the nucleus of a cell and formed from nucleotides and shaped like a double helix; associated with the transmission of genetic information.
But even adults don't often know what a notochord is. A notochord is a primitive beginning to the backbone. It appears in embryos as a small flexible rod made from cells from the mesoderm, which is one of the three layers of cells of embryos. Notochords are only found in the phylum chordata, a group of animals that includes humans.
There are two invertebrate subphyla: the Urochordata, or tunicates tunicate, marine animal of the phylum Chordata, which also includes the vertebrates. The adult form of most tunicates (also called urochordates) shows no resemblance to vertebrate animals, but such a resemblance is evident in the larva......hordata. (kordÄ`kÃ´rdÄ,âtÉ`â) , dae dÃ¤ phylum of animals having, a notochord or dorsal, stiffening rod as the chief internal skeletal support at some stage of. Their development most chordates (are vertebrates animals), with backbones but the phylum also includes some small marine. invertebrate animals