Question

Water current in a sponge/Leucosolenia is maintained by
A) Pinacocytes
B) Porocytes
C) Choanocytes
D) Amoebocytes

Answer 1

The animal kingdom consists of numerous organisms that are classified according to their characteristics like; cellular structure, body structure, habitat, tissue arrangement, etc. Sponges belong to Protista as they are multicellular heterotrophic animals.

Complete Answer:
- Sponges are the aquatic organisms found in marine water and sometimes in freshwater, they are found in warm water. They have pores in their body that are of two types; inhalant pore that is ostia and exhalant pore that is oscula.
- The body is asymmetrical and sometimes radially symmetrical. They are the first diploblastic animal that means they are formed from two germ layers called ectoderm and endoderm.

- Now, the body wall of the sponges consists of three layers; pinacoderm, choanoderm, and mesohyl layer.
- The pinacoderm is the outer covering that consists of porocytes and flattened pinacocytes, the choanoderm is the gastral layer, it is the cellular layer that comprise of specialized flagellated cells termed as collar cells or choanocytes this layer involved in the maintaining of water current inside the sponge, and the mesohyl layer is found between the choanoderm and pinacoderm, it consists of dispersed sponging fibres and many spicules. It also consists of amoebocytes of choanoderm and pinacoderm.
- The amoebocytes are modified into archaeocytes that is converted into undifferentiated cells, the trophocytes that provide food to the growing cells therefore, it is named as nurse cell, the thesocytes that involve in storage of food granules, the gland cells produce some slimy substance that involve in providing protection to the organism, collencytes produce spongin fibres, the sclerocytes produce spicules, and the germ cells are developed in the breeding season that form ova and sperm.

**Thus, the correct option is ‘C’. Choanocytes.

Note: Both the asexual and sexual reproduction takes place in sponges. By bud and gemmules formation asexual reproduction takes place. They are hermaphrodites and undergo internal fertilization.