Question

Which one of the following is a freshwater sponge?
A. Sycon
B. Euspongia
C. Spongilla
D. Euplectella

Answer 1

Hint: Phylum Porifera belongs to the sponges. Sponges are pore bearing animals. Sponges being aquatic either live in the marine or in the freshwater. They have a water transport system. These help in finding foods.

Complete answer: A water transport system or canal system is present in sponges. Ostia are minute pores present in the body wall through which water enters and goes into a central cavity called the spongocoel. Water goes out through the osculum. This transportation helps in gathering food, exchange of respiration, and waste removal.
-Sycon belongs to the Class Calcarea and is mostly found in shallow water.
-Euspongia belongs to the Class Demospongiae and has a skeleton made of spongin fibers. It is found in the marines and has commercial importance.
-Spongilla belongs to the Class Demospongiae and has a skeleton made of spongin fibers. It is extensively found in the freshwater. Due to the symbiotic algae present inside, it shows different shades of green colour.
-Euplectella is also known as venus flower basket. it lives in the deep-sea water.
Thus, the correct option is C, i.e., Spongilla.

Additional information: -
Hyalonema is a glass rope sponge. A root tuft of long, twisted spicules fixes Hyalonema in the mud. Cliona is a boring sponge that has the ability to penetrate rocks and break them into pieces. Chalina is a type of sponge that is popularly known as the deadman’s fingers because it has a shape similar to a hand with fingers perforated with oscula.

Note: The phylum porifera has advanced over the phylum protozoa and has a multicellular body. The presence of ostia, canal system and spicules make the phylum unique. They are extensively found in freshwater.