Question

In sponges, which structure is used for excretion?
A. Contractile vacuole
B. Flame cells
C. Nephridia
D. Osculum

Answer 1

Hint: Sponges are aquatic organisms that have a dense porous exoskeleton. They have various pores in their skeleton that help in the exchange of various materials between the organism’s body and
the environment.

Complete answer:
Sponges are multicellular organisms that belong to the phylum Porifera. They have a dense skeleton that is adapted to the environmental conditions. They have an exterior porous structure that helps in the uptake of various substances such as nutrients, oxygen, and food. They also have a single large opening which is known as osculum. Osculum helps in the removal of excretory products. The small pores are known as ostia. In sponges, the nitrogenous wastes are produced as a byproduct of protein metabolism. The excretory waste produced is removed by the individual cell in the organism by the process of diffusion. The water enters into the sponges through minute pores or ostia and exits through the osculum or large opening.

Hence, the correct option is Option D-Osculum.

Note: In sponges, the osculum is an excretory structure. It is an opening to the outside through
which water exits after passing through the spongocoel. The excretory waste diffuses into the water
entering the spongocoel and is pumped away from the osculum, thus removing the wastes from the
sponge’s body. It is a large opening that helps in water absorption and release. It is an important
component of the water-current system.