Question

Consider the following features.
a. Water vascular system
b. Radial symmetry in adults
c. Organ system level of organization
Select the correct set of animals which possess all the above characteristics.

A Loligo, Octopus, Sepia B Asterias, Echinus, Ophiura C Limulus, Locusta, Aedes D Physalia, Adamsia, Pennatula

Answer 1

The correct answer is option B.

All the given characteristics are present in Asterias, Echinus, and Ophiura.

• All the there organisms belong to the phylum, Echinodermata.

• The important features of Echinodermata are given below:

1. Triploblastic

2. Unsegmented body without any head.

3. Larval forms have bilateral symmetry whereas adult forms have radial symmetry.

4. No true coelom.

5. Calcareous spicules present on the body surface.

6. A nervous system with radial nerve cords are present.

7. Respiration takes place with the help of gills and tube feet.

8. External fertilisation.

Answer 2

B) Asterias, Echinus, Ophiura

Explanation:

Asterias, Echinus and Ophiura belong to the Phylum Echinodermata. These are exclusively marine animals, so they possess water vascular system. These animals exhibit bilateral symmetry in larva stage. But adult animals of this phylum exhibit radial symmetry like humans. Echinodermata exhibit organ system grade of organization and have a true coelom. So all the 3 features mentioned in the question is commonly found in these three animals.

Option B is the answer.