Q.Mention the characters shared between Chordata and Echinodermata.

[!TLDR] Chordata and Echinodermata share deuterostome development: blastopore → anus, radial cleavage, enterocoelous coelom.

[!ANSWER] Chordata and Echinodermata are both deuterostomes: in both, the embryonic blastopore develops into the anus (not the mouth), cleavage is radial and indeterminate, and the coelom forms enterocoelously, as outpocketings of the embryonic gut.

[!ANSWER] Chordata shares its most fundamental developmental characters with phylum Echinodermata, despite the two phyla looking completely different as adults.

Both phyla are deuterostomes: the blastopore, the first opening formed during gastrulation, develops into the anus rather than the mouth (with the mouth forming secondarily); early cleavage of the embryo is radial rather than spiral, and indeterminate rather than determinate (the fate of each cell is not fixed as early as in protostomes); and the coelom forms by enterocoely, arising as outpocketings of the wall of the embryonic gut (archenteron), rather than by the schizocoelous splitting of a solid mesodermal mass seen in protostome phyla such as Annelida and Arthropoda.

This shared developmental pattern is why Chordata and Echinodermata (along with the smaller phylum Hemichordata) are grouped together as the deuterostome phyla, even though the adult echinoderm body plan (radially symmetrical, water-vascular system, calcareous ossicles) looks nothing like the adult chordate body plan.

[!ANSWER] Chordata and Echinodermata share the deuterostome pattern of development: blastopore → anus, radial/indeterminate cleavage, and enterocoelous coelom formation — the basis for grouping them, with Hemichordata, as the three deuterostome phyla.

• Assuming the two phyla are similar because of adult body plan — the shared features are strictly developmental (embryonic), not seen in the adult form.
• Confusing enterocoely (Deuterostomia) with schizocoely (Protostomia).