Question

What is the largest subphylum of chordates?

Answer 1

Hint: Chordates are living beings that are classified in the kingdom Animalia. It is a group of animals or phylum, which includes three subphyla, namely, Vertebrata, Urochordata (tunicates), and Cephalochordata (lancelets). Chordates possess a notochord, pharyngeal gill arches, thyroid gland, post-anal tail, and tubular nerve cord.Inthe animal kingdom, the Chordata is the third-largest phylum.

Complete answer:

                                       Fig: Classification of Phylum Chordata into its Subphyla
Vertebrates contribute the vast majority of chordates. There are eight classes of vertebrates. Four are aquatic and four are terrestrial or semi-terrestrial (amphibians). The four aquatic subphyla can be grouped as superclass fishes or Pisces. They are grouped as superclass Tetrapoda or four-footed animals.
Vertebrata is the largest and most diverse subphylum of chordates, with its evolution supported by efficient respiration, advanced nervous system, paired limbs, and the living endoskeleton.
The largest subphyla of chordates are vertebrates, which are inclusive of $66000$ species. Vertebrate is often equivalent to an animal. Vertebrate is named after the vertebral column, which is a common feature for almost all members.
Vertebrates include all animals, which possess a central nervous system, gills, and backbones, during at least one phase of development. They include reptiles, mammals, birds, amphibians, jawless fishes, sharks, rays, and bony fishes.
All the vertebrates are built along with a vertebral column running throughout the length of the animal with a spinal cord or tube of nerve tissue, gastrointestinal tract below it, and a basic chordate body plan. The cord is generally made of bones.

Note:
The blue whale is the world’s biggest chordate. It is even larger than the dinosaurs. The population of the blue whale is less than $1$% now due to the higher rate of hunting before $1960$. A notochord is a flexible rod, which runs along the dorsal side of the animal. In humans, notochord develops into the spinal cord, providing the identity as a chordate. In some chordates, the notochord is replaced by a backbone at some parts of life.