Question

Which one is sedentary Echinoderms?
A. Echinus
B. Ophiura
C. Starfish
D. Antedon

Answer 1

Hint:- Echinoderms is the phylum name given to marine animals. The adult species that come under echinoderms is found with radial symmetry that has five points, this phylum contains around seven thousand living species. They are important for both ecologically and geologically.

Complete answer: All echinoderms are marine and benthic that are found at the lowest bed of the ocean or sea. The larvae of all these echinoderms are usually bilaterally symmetrical as they grow and become adults they form radial symmetry. They keep themselves attached to the bed of the ocean or sea till they grow and become adults. They have the unique feature of giving rise to newborn from their five parts. Some of the examples of echinoderms are starfish, crinoid, sea cucumber etc. One of the characteristics of echinoderms is they have a special kind of tissue which is known as catch connective tissue which have the special feature of changing its mechanical property in a few seconds or minutes through their nervous control which makes them as flexible as water or as rigid as land to escape from predators. These all features from above mentioned options are found in “Antedon'' which is an echinoderm of all of the above. It is also known as a feather star that has ten pinnate arms with side branches like a feather. It is a sedentary deep-sea echinoderm; it is fixed in the ocean bed by the cirri and it feeds microscopic plankton and debris.
Hence the correct option is (D) Antedon

Note:- They possess a simple digestive system which varies in accordance with their diet. As star fish is carnivorous and has a mouth, oesophagus with two part stomach intestine and rectum with anus at the centre. They reproduce sexually and asexually both.