Question

How do pores or holes present over the body of poriferans important?
A. The pores or holes present all over the body of poriferans lead to a canal system that helps in circulating water throughout the body to bring food and oxygen throughout.
B. The pores or holes present all over the body of poriferans lead to endocrine that helps in circulating water throughout the body to bring food and oxygen throughout.
C. The pores or holes present all over the body are just for beatification.
D. Both A and B

Answer 1

Hint: The presence of holes all over the body uses a distinguishing feature of all types of sponges. The function of these numerous pores is entry and exit of water. The pores through which water enters are known as ostia and pores through which water goes out are known as osculum. Members of porifera are commonly known as sponges.

Complete answer:
The inhalant pores ostia leads to a single, central cavity known as spongocoel either directly or through small canals. From the spongocoel water go out through the exhalant pores osculum.
The canals and spongocoel are internally lined by flagellated cells known as choanocytes.
The body of sponges have a complex system of pores and canals known as canal system.
Functions of canal system:
> Waste removal: The undigested residue and metabolic waste chiefly ammonia eliminated with the help of water through the osculum.
> Exchange of gases: Exchange of gases like oxygen and carbon dioxide occur through water entering and going out of the canal system.
> Food gathering: The food is gathered with the help of canal system and after entering the body food is captured by collar cells for digestion.
> Sperm transfer: Sperm from one sponge enter the other sponge with the help of water.

So, the correct options (A).

Note:
In sponges canal system is of three types these are:
> Ascon type
> Sycon type
> Leucon type
Choanocytes also known as collar cells as they contain a central flagellum surrounded by rings of microvilli. These microvilli help filter nutrients from the water entering the fungus. With the help of these choanocytes, the sponge receives microscopic nutrients as filter food for the microvilli. Hence sponges are the filter-feeders. Most sponges are marine but Spongilla is a freshwater sponge.