Question

Which one of the following is a matching set of a phylum and its three examples?
A) Porifera: Spongilla, Euplectella, Pennatula
B) Cnidaria: Bonellia, Physalia, Aurelia
C) Platyhelminthes: PLanaria, Schistosoma, Enterobius
D) Mollusca: Loligo, Teredo, Octopus

Answer 1

In order to classify organisms, the basic characteristics of each phylum and each organism must be known. Only then is it possible to decide whether or not they can be combined, sometimes to the point of one characteristic being different.

Complete answer:
The correct answer is (D). Mollusca contains animals with soft bodies, tentacles, often a shell which is internal or external, and a muscular foot. Squids, shipworms, and octopuses all belong to Mollusca, having several of these features.
Option A is incorrect because even though sponges and Euplectella do belong to Porifera, a phylum with irregular structures and the presence of a coelom, while Pennatula are classified as Coelenterata with radial symmetry and the absence of a coelom.
Similarly in option B, the examples physalia and Bonellia do belong to Cnidaria, Cnidarians are a very diverse group, but Aurelia is a true worm belonging to the phylum Annelida, segmented worms with a body cavity divided by rings or annulae.
Option C is also an incorrect answer. The pinworm Enterobius belongs to the phylum Ascelminthes. Planaria and Schistosoma are true Platyhelminthes. Platyhelminthes are flatworms with an incomplete digestive system; aschelminthes are cylindrical with a separate mouth and anus.

Hence the correct answer is OPTION(D)

Note: Even though most animals are well classified in one or the other phylum or family, there are instances where scientists find it difficult to come to an agreement. For instance, Euglena has a chloroplast an is single celled, and has been classified both as plant and animal