fish

A primitive chordate(although superior to sea squirts) that is built for swimming and most breath underwater with gills and have fins (i.e. dorsal, pectoral, etc.) They usually have scales except lampreys, hagfish, and eels to protect them. Their skeletons can be cartilage or bone and come in a variety of shapes, colors,sizes,diets,habitats,reputations,etc. Some of them are primitive, like lampreys and hagfish, cartilageous, like sharks, skates, and rays, and bony,like tuna, clownfish, etc. Did I say that they are prehistoric and lived before the dinosaurs, were the first vertebrates, and evovled from invertibrate worm chordates.