Why is a cockatoo in the phylum Chordata?

Answer 1

To answer the question in the simplest way, the cockatoo has a backbone.

However, there is more to it than that, especially given that there are two invertebrate chordate groups - Urochordata (tunicates) and Cephalachordata (lancelets) - whose backbone is not in the form of actual vertebrae.

As Chordates (or members of the phylum Chordata), cockatoos share the following characteristics:

dorsal nerve cord which is a bundle of nerve fibres which runs down the back. It connects the brain with the lateral muscles and other organs.

notochord which is a cartilaginous rod running underneath, and supporting, the nerve cord - in the case of the cockatoo, a spine.

post-anal tail - an extension of the body past the anal opening. (This feature is not always present in some adult Chordates such as frogs and humans, but it is present in the cockatoo.)

Pharyngeal pouches - Chordates, at some stage of their life, have pharyngeal grooves and pouches that develop into other essential parts of their anatomy.