Question

Hard calcium carbonate structures are used as skeleton by

• A. Echinodermata
• B. Protochordata
• C. Arthropoda
• D. Nematoda

Answer 1

The correct option is A

Echinodermata

An explanation for the correct answer.

Correct Option A:

1. As the term is indicating, they are spiny-skinned
2. The body cavity is modified into a unique water vascular system.
3. The body wall is covered by spiny hard calcareous (calcium carbonate) plates which makes the body rigid as well as flexible.

An explanation for the incorrect answer

Incorrect Option B:

Protochordates do not have such skeletons.

Incorrect Option C:

Calcium carbonate structure is not present in Arthropoda.

Incorrect Option D:

Calcium carbonate structure is not present in Nematoda.

Final answer: Hard calcium carbonate structures are used as skeletons by Echinodermata.