Question

‘Basket star’ belongs to class of
A. Ophiuroidea
B. Echinoidea
C. Crinoidea
D. Asteroidea

Answer 1

Hint:- ‘Basket star’ is also known as ‘Shetland Argus’. They possess typical repeated branched arms. They are found in deep-sea habitats. Blood is not present in these organisms and the gas exchange in their body occurs through the water vascular system.

Complete step-by-step solution:-
The structure of basket stars is similar to that of brittle stars, but basket stars are generally larger. The bodies of basket stars have a central disk from which multiple branched arms protrude out producing thousands of branchlets. Their arms are long and flexible. The largest arm measured was up to 70 cm in length with a disk having a diameter of 14 cm. Their arms are supported with an internal structure made up of calcium carbonate. Their arms also bear soft spines. They possess a single digestive system. They filter-feed on the planktons with the help of their arms.
Basket stars are mostly found in marine habitats with shallow water. They come under the order Euryalina and order Euryalida. They belong to class Ophiuroidea. They are the largest group of ophiuroids.
So the correct option is (A) Ophiuroidea.

Additional information:- Ophiuroids is a large group under Echinoderms having more than 1600 species. Because of the flexibility of their arms, they are given the name ‘snake stars’. They can move very quickly with the help of these arms. The internal structure of arms made of calcium carbonate looks similar to vertebrae and thus are called vertebral ossicles.
Ophiuroids are found all over the world. They are dominant over the deep seas. Mostly they are scavengers and detritus feeders.

Note:- The lifespan of basket stars is about 35 years. They weigh approximately 5 kilograms when fully grown. They are also seen to be mutually associated with other organisms, mostly, sponges.