Biology · Animal Kingdom · NEET
NCERT says chordates are fundamentally characterised by THREE features: (1) a notochord, (2) a dorsal, hollow nerve cord, and (3) paired pharyngeal gill slits. These three define a chordate. Note the word 'fundamental' - only these three are the defining trio. Other traits like post-anal tail, closed circulation and ventral heart are also present but are usually listed as supporting features.
No. The notochord is a rod-like support structure present AT SOME STAGE of life. In Cephalochordata it stays head-to-tail for whole life. In Urochordata it is only in the larval tail. In Vertebrata (us, fishes, frogs) the notochord is present in the embryo only, and later it is replaced by the vertebral column (backbone). So 'present at some stage' is the safe answer for NEET.
In chordates the nerve cord is DORSAL (on the back side), HOLLOW (tube-like), and SINGLE. This is a top NEET trap. In non-chordates (like Annelida, Arthropoda) the nerve cord is VENTRAL (belly side), SOLID, and DOUBLE. So if a statement says 'mid-dorsal solid double nerve cord', it is WRONG for chordates.
The chordate heart is VENTRAL (on the belly side). In non-chordates, the heart is dorsal if present. NEET 2023 and NEET 2024 both tested this exact swap. Easy trick: chordate has nerve cord on TOP (dorsal) and heart on the BOTTOM (ventral) - they are on opposite sides.
Chordates are triploblastic, bilaterally symmetrical, TRUE COELOMATES with organ-system level of organisation and a CLOSED circulatory system. They are NOT pseudocoelomate (that is Aschelminthes/roundworms). NEET 2023 marked the statement 'triploblastic pseudocoelomate animals' as WRONG for chordates.
They are two different structures. The NOTOCHORD is a flexible rod that gives skeletal SUPPORT and lies below the nerve cord. The DORSAL HOLLOW NERVE CORD is part of the NERVOUS system and lies above the notochord, on the back. One supports the body (notochord), the other carries nerve signals (nerve cord). Do not mix them up.
Select the correct statements with reference to chordates. A. Presence of a mid-dorsal, solid and double nerve cord. B. Presence of closed circulatory system. C. Presence of paired pharyngeal gill slits. D. Presence of dorsal heart. E. Triploblastic pseudocoelomate animals.
The following are the statements about non-chordates: A. Pharynx is perforated by gill slits. B. Notochord is absent. C. Central nervous system is dorsal. D. Heart is dorsal if present. E. Post anal tail is absent. Choose the most appropriate answer.
Which of the following is not a characteristic of chordates?
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Notochord, dorsal hollow nerve cord, and paired pharyngeal gill slits. Remember the trio as 'N-N-G'.
A single, dorsal (back side), hollow (tube-like) nerve cord. Non-chordates have a ventral, solid, double nerve cord.
On the ventral (belly) side. Non-chordates have a dorsal heart if a heart is present.
No. All vertebrates are chordates, but not all chordates are vertebrates. Urochordata and Cephalochordata are chordates without a backbone.
Yes. Chordates are triploblastic, bilaterally symmetrical, true coelomates with organ-system level of organisation and a closed circulatory system.
