Question

Heterocoelus calcareous sponge is

• A. Grantia
• B. Euplectella
• C. Hyalonema
• D. Pheronema

Answer 1

Answer: (A)

Grantia

• In the biological classification of the phylum Porifera, the sponge Grantia is placed under the class Calcarea and the order Heterocoela. The skeleton of Calcareous sponges comprises of a large number of minute, crystalline, calcareous spicules. The Heterocoelus sponges are mainly characterized by the Syconoid type of canal system. Grantia possesses both of these features and thus, is recognized as a Heterocoelus Calcareous sponge.
• The sponges Euplectella, Hyalonema and Pheronema fall under the class Hexatinellida. The skeleton of Hexactinellid sponges comprises of a large number of crystalline, siliceous spicules. The siliceous spicules of the Euplectella are 6-rayed and star-like in shape while the spicules of Hyalonema and Pheronema are shaped like amphidiscs.
• Hence the correct option is A.