Question

Give three major differences between chordates and non-chordates and draw a schematic sketch of a chordate showing those features.

Answer 1

Animals belonging to phylum Chordata are fundamentally characterised by the presence of a notochord, a dorsal hollow nerve cord and paired pharyngeal gill slits. These are bilaterally symmetrical, triploblastic and coelomate with the organ-system level of organisation. They possess a post-anal tail and a closed circulatory system.

S.No.	Chordates	Non - chordates
1.	Notochord present.	Notochord absent.
2.	Central nervous system is dorsal, hollow and single.	Central nervous system is ventral, solid and double.
3.	Pharynx perforated by gill slits.	Gill slits are absent.
4.	Heart is ventral.	Heart is dorsal (if present).
5.	A post-anal part (tail) is present.	Post-anal tail is absent.

                  Chordata characteristics