EVERYDAY SCIENCE

Detailed explanation-1: -osculum. / (ˈɒskjʊləm) / noun plural-la (-lə) zoology a mouthlike aperture, esp the opening in a sponge out of which water passes.

Detailed explanation-2: -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.

Detailed explanation-3: -Water enters through pores called ostia, flows through canals to a spacious chamber called a spongocoel, and finally exits through large openings called oscula. Often, sponges are distinguished by the level of complexity exhibited by their bodies.

Detailed explanation-4: -Sponges are perforated by many tiny pores called ostia that permit water to enter one or more oscula (singular osculum) that let the water exit. These openings are connected by a series of canals, some of which are lined by collar cells called choanocytes whose flagella maintain a flow of water through the sponge.