Which term refers to the phylum that includes all vertebrates?

Which term refers to the phylum that includes all vertebrates?

• A. Chondrichthyes
• B. Chordata
• C. Crustacea
• D. Cnidaria

Answer: (B)

Chordata is the phylum that includes all vertebrates. Animals in this group share key features at some stage of development, such as a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail. In vertebrates, the notochord is usually replaced by a backbone, but these defining chordate characteristics still place them in this phylum. The other options don’t fit because one is a class of vertebrates (cartilaginous fishes) within the same phylum, another is a subphylum of arthropods, and the last is a separate phylum altogether that includes jellyfish and corals.

Chordata is the phylum that includes all vertebrates. Animals in this group share key features at some stage of development, such as a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail. In vertebrates, the notochord is usually replaced by a backbone, but these defining chordate characteristics still place them in this phylum. The other options don’t fit because one is a class of vertebrates (cartilaginous fishes) within the same phylum, another is a subphylum of arthropods, and the last is a separate phylum altogether that includes jellyfish and corals.