EVERYDAY SCIENCE

Detailed explanation-1: -A dorsal hollow nerve tube is a common feature of all chordates, including humans, in both embryonic and mature stages. All chordates have a post-anal tail that is located posterior to the anal opening (Fig. 3.98).

Detailed explanation-2: -Animals in the phylum Chordata share four key features: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.

Detailed explanation-3: -The phylum chordata is named for the notochord, a longitudinal, flexible rod between the digestive tube and the nerve cord; in vertebrates, this is the spinal column. The chordates are also characterized by a dorsal nerve cord, which splits into the brain and spinal cord.

Detailed explanation-4: -Characteristics of Chordata The dorsal hollow nerve cord derives from ectoderm that rolls into a hollow tube during development. The nerve cord found in most chordate embryos develops into the brain and spinal cord, which comprise the central nervous system.

Detailed explanation-5: -Characteristics of Chordata Animals in the phylum Chordata share five key chacteristics that appear at some stage during their development: a notochord, a dorsal hollow (tubular) nerve cord, pharyngeal gill arches or slits, a post-anal tail, and an endostyle/thyroid gland (Figure).