Question

1. why are ostia important to sponges?

they pull water into the sponge through the beating of their flagella.
they are what the gel is composed of that connects all the different cells of the sponge together.
they are the pores through which water, sperm, and food enter the sponge.
they are large openings in the sponge that allow the waste to exit.

Explanation:

To determine the correct answer, we analyze each option:

• The first option describes the function of choanocytes (cells with flagella), not ostia.
• The second option refers to the mesohyl (the gel - like substance), not ostia.
• The third option: Ostia are indeed the pores in sponges through which water, sperm, and food enter the sponge. This matches the definition and function of ostia.
• The fourth option describes the osculum (the opening for waste exit), not ostia.

Answer:

C. They are the pores through which water, sperm, and food enter the sponge.