Question

Which phylum of animals were earlier placed under chordates but now are considered as non-chordates?

• A. Urochordates
• B. Cephalochordates
• C. Hemichordates
• D. Protochordate

Answer 1

The correct option is C Hemichordates

Hemichordates were earlier placed under the chordates due to certain chordate characters like

• presence of stomochord in the anterior region of the body, a structure similar to the notochord
• presence of dorsal nerve cord, though ventral nerve cord also present
• presence of gill slits

But in the recent classification systems, they are considered as non-chordates. Recent DNA based studies show that the hemichordates are more closely related to echinoderms. The larva of hemichordates is very much similar to echinoderms.

Protochordate is an informal category which consists of the phylum Hemichordata and subphyla Urochordata and Cephalochordata. It includes animals that resemble vertebrates, but are not.