Question 59 of 75
Q.Differentiate Chordates and Non-Chordates.
Tamil Nadu DgeTamil Nadu HSC First Year (DGE) Board 2023Subjective· 3mImportance★★★★★
79% · 59/75 Questions
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Start your 14-day free trial to unlock the full solution →The defining differences are the presence of a notochord, dorsal tubular nerve cord and pharyngeal gill slits in chordates, all of which are absent in non-chordates.
Chordates:
- Possess a notochord (a flexible rod-like axial support structure) at some stage of life, replaced by the vertebral column in most adult vertebrates.
- Have a single, dorsal, hollow (tubular) nerve cord running above the notochord.
- Possess pharyngeal gill slits at some stage (even if only in the embryo, as in mammals).
- Have a post-anal tail at some stage.
- Circulatory system is closed, with a ventral, contractile heart.
- Examples: fishes, amphibians, reptiles, birds, mammals (and simpler chordates like Amphioxus).
Non-chordates:
- Never develop a true notochord.
- If a nerve cord is present, it is ventral and typically solid (not dorsal and hollow), e.g., the ventral nerve cord of earthworms and insects.
- Lack pharyngeal gill slits and a post-anal tail. …
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