Question

Which of the following is not the character of chordata?
A)Dorsal tubular nerve cord
B)Pharyngeal gill slits
C)Presence of notochord
D)Presence of spinal cord

Answer 1

Phylum Chordata belongs to the Kingdom of Animalia and comprises all vertebrates, i.e. backbone animals, and some invertebrates, i.e. backbone-free organisms. They are divided into three distinct sub-phyla and have a bilaterally symmetrical skeleton.

Complete answer:
The following characteristic features are present in Phylum Chordata:

1.Notochord Notochord
It is a longitudinal, cartilaginous rod running between the digestive tract and the nerve cord. It functions as a nerve cord support and is replaced in all vertebrates by the vertebral column after the embryonic point.

2.Dorsal Nerve Cord
It is a group of nerves that flow along the "back" and divide into the brain and the spinal cord. It is hollow, and the notochord lies dorsally.

3.Pharyngeal Slits
They are the openings that make it possible for water to enter through the mouth without entering the digestive system. The mouth and throat are linked. At some stage of their lives, all chordates have these openings on the lateral sides of the pharynx.

4.Post and Tail
It is a body extension to the anus. In chordates, the tail consists of skeletal muscles that in fish-like species assist in locomotion. In the majority of adult chordates, it is absent.

5.Other features of chordates include:
Symmetrical, triploblastic, coelomic, and segmented body, bilaterally.
The body layout is diverse and well-differentiated.
The body has the organisational level of an organ system.

Hence, the correct answer is option (D)

Note: Phylum Chordata is divided into three subphyla, i.e.
1.Urochordata (tunicates)
2.Cephalochordata (lancelets)
3.Vertebrata, (vertebrates)
The Urochordata subphylum and Cephalochordata are collectively referred to as protochordates, which are aquatic animals. They are invertebrates, but chordates have characteristics that they share.