Hard calcium carbonate structures are used as skeleton by
(a) Echinodermata
(b) Protochordata
(c) Arthropoda
(d) Nematoda
Answer- (a)
Solution- Sea urchin belongs to phylum Echinodermata. These are spiny skinned organisms found in marine water. They are triploblastic and have a coelomic cavity. They produce calcium carbonate plates that fit together tightly.
The correct answer is- a)- Echinodermata