Describe the Phylum Chordata in animal kingdom?
This is the other group of animals along with the Echinodermata whose anus develops prior to the mouth's development in the embryological process. Sharing this similar embryology is thought to reflect the fact that Echinoderms and the chordates had a common ancestry. Consider how different the sea stars and sea cucumbers are from snakes, frogs, birds, fishes, and mammals!
There are three major features that distinguish the chordates from all other animals.
1. A hollow nerve cord running along the length of the back, or dorsal, side.
2. A flexible notochord that provides support and protection along the length of the nerve cord. In some cases it remains a notochord in the adult, and in other cases, it is replaced by a vertebral column in adult stages.
3. Pharyngeal gill slits that open to the outside in the throat area behind the mouth. In some species, pharyngeal slits function in filter feeding, and in other species the slits become modified into gas exchange organs, or gills.
One additional characteristic feature that most chordates have is a tail that extends beyond the anus. One system of classification separates the Phylum Chordata into three subphyla: