Ch 4Animal Diversity-II: Phylum Chordata — Class 11 Zoology, concept-first.

Phylum Chordata is defined by four hallmark structural features, present at some stage of the life cycle in every member of the phylum:

Tunicates (also called sea squirts, urochordates) are marine animals that, as sessile, saclike adults, look nothing like typical chordates — the adult tunicate has no visible notochord, no post-anal t…

Cephalochordates — represented by the lancelet, Amphioxus (Branchiostoma) — are small, elongated, fish-shaped marine animals that, unlike the tunicates, retain all four chordate hallmark features thro…

Class Pisces (fishes) comprises exclusively aquatic, gill-breathing vertebrates, and is broadly divided into cartilaginous fishes (sharks and rays) and bony fishes (the great majority of living fish,…

Class Amphibia occupies a transitional position between the wholly aquatic fishes and the wholly terrestrial reptiles, and its members typically show a life cycle divided between an aquatic larval sta…

Reptiles are the first class of chordates, among those covered in this chapter, to be fully independent of an aquatic larval stage, showing direct development and full adaptation to terrestrial life (…

Birds are the chordate class most extensively and visibly modified for flight, and nearly every major organ system shows some adaptation serving this single overriding function.

Mammals are the chordate class showing, among other features, mammary glands (producing milk to nourish the young), hair, and, typically, viviparity (in the majority of living mammals, the Eutheria/pl…

Sample papers and previous-year board questions for this subject.