Question

Spongocoel is lined by
A. Porocytes
B. Choanocytes
C. Amoebocytes
D. Spicules

Answer 1

Hint: A spongocoel is the large, central cavity of sponges (Porifera). Water enters the spongocoel through hundreds of tiny pores and exits through the larger opening. The spongocoel is lined by a variety of cells: Porococytes, Choanocytes, and Amoebocytes.

Complete answer:
In this question we have asked about the lining of spongocoel. First we'll learn about spongocoel. As we already mentioned, a spongocoel is the large, central cavity of sponges (Porifera). The main function of spongocoel is nutrition. Water enters into this cavity by pores except the largest pore called osculum, from which, they separate food and then water leaves.

> Option A is porocytes. Porocytes are tubular cells which make up the pores of a sponge.

> Option B is choanocytes. Choanocytes are present at many locations, but mainly they line the inner portions of some spongocoel while pinacocytes line the outside of the sponge. It generates water current and traps the food.

> Option C is amoebocytes. As the name suggests, it is amoeba like cells, they can move to any location in the sponge, but they're usually found in the mesohyl (mesohyl is a gel-like substance found between a sponge's epithelial layers).

> Option D is spicules. Spicules are secreted by some sponges, which are composed of either calcium carbonate or silica.

Hence, The correct answer is option (B).

Note: Choanocytes or collar cells are distinctive cells. They have a central flagellum which is surrounded by a microvilli which are connected by a thin membrane. This cell is endodermal in origin.