NEET BIOLOGY

Detailed explanation-1: -These pores are sometimes also referred to as ostia, and they provide openings for water, which carries planktonic food and oxygen, to enter the sponge body (Fig. 3.19). Simple vase-like sponges have a single large top opening, called the osculum through which water leaves the sponge.

Detailed explanation-2: -The osculum is a large opening that forms the excretory tract of the sponge. The size of the osculum opening is determined by contractile myocytes as the size regulates the volume of water expelled from the sponge.

Detailed explanation-3: -The osculum (plural “oscula") is an excretory structure in the living sponge, a large opening to the outside through which the current of water exits after passing through the spongocoel.

Detailed explanation-4: -Calcareous sponges of the genus Scypha are shaped like tubular sacs, with an opening (osculum) at the tip.

Detailed explanation-5: -Ostia are the inhalant pores in the body of sponges. Water enters the body of sponges through ostia and reaches the spongocoel. It then flows out of the body through osculum. Ostia is present only in sponges i.e. phylum Porifera as sponges have a porous body.