Which term is not a class within the Phylum Chordata?

Which term is not a class within the Phylum Chordata?

• A. Amphibia
• B. Osteichthyes
• C. Echinoderm
• D. Chondrichthyes

Answer: (C)

Chordates are defined by features that appear at some life stage, such as a notochord, a dorsal nerve cord, pharyngeal slits, and a post-anal tail. Within this phylum you’ll find many classes, including Amphibia, Osteichthyes, and Chondrichthyes, all of which share those key chordate characteristics. Echinoderm, however, belongs to a different phylum, Echinodermata, and its members have radial symmetry and a water vascular system rather than a true notochord or dorsal nerve cord. They are deuterostomes like chordates, but they are not chordates themselves. So the term not a class within Phylum Chordata is Echinoderm.

Chordates are defined by features that appear at some life stage, such as a notochord, a dorsal nerve cord, pharyngeal slits, and a post-anal tail. Within this phylum you’ll find many classes, including Amphibia, Osteichthyes, and Chondrichthyes, all of which share those key chordate characteristics. Echinoderm, however, belongs to a different phylum, Echinodermata, and its members have radial symmetry and a water vascular system rather than a true notochord or dorsal nerve cord. They are deuterostomes like chordates, but they are not chordates themselves. So the term not a class within Phylum Chordata is Echinoderm.