AP BIOLOGY

Detailed explanation-1: -Chordata is a familiar phylum comprising organisms such as mammals, fish, birds, reptiles and amphibians (all vertebrates); marine squirts (tunicates); and lancelets (cephalochordates). At some point in their development, all chordates have a notochord, a dorsal nerve cord, and pharyngeal slits.

Detailed explanation-2: -The phylum Chordata consists of animals with a flexible rod supporting their dorsal or back sides. The phylum name derives from the Greek root word chord-meaning string. Most species within the phylum Chordata are vertebrates, or animals with backbones (subphylum Vertebrata).

Detailed explanation-3: -The phylum chordata (animals with backbones) is divided into five common classes: fish, amphibians, reptiles, mammals and birds.

Detailed explanation-4: -> Option B: Based on the common features like presence of notochord and dorsal hollow neural system, animals like fishes, amphibians, reptiles, birds along with mammals are included in Phylum Chordata. Hence, this is the correct option.

Detailed explanation-5: -Chordates are divided into three subphyla: Craniata (fish, amphibians, reptiles, birds, and mammals); Tunicata or Urochordata (sea squirts, salps); and Cephalochordata (which includes lancelets). The Craniata and Tunicata compose the clade Olfactores, which is sister to Cephalochordata. (See diagram under Phylogeny.)