Question

Sponges have originated from

• A. Ciliate protozoans
• B. Sporozoan protozoans
• C. Sarcodine protozoans
• D. Choanoflagellate protozoans

Answer 1

The correct option is D Choanoflagellate protozoans

Sponges probably arose from flagellated protozoans. The choanocytes of sponges resemble the choanoflagellate protozoans. Choanoflagellate protozoan colonies, however, do not develop by way of embryological stages as do the sponges. The primitive structure of the Porifera indicates affinities with certain types of protozoan colonies, both lack integration of parts, mouth and digestive systems and both have a type of skeletal formation in which single elements are produced by a single cell or by a small group of cells.

Hence the correct option is D.