Final answer:
In sponges, water and nutrients enter through incurrent pores and exit along with waste through the osculum. The spongocoel is the large central cavity where filtering and digestion take place.
Step-by-step explanation:
In a sponge, water and nutrients enter through the incurrent pores, and water and waste exit through the osculum. Sponges pump water into their body through incurrent pores. This water, which contains dissolved oxygen and food particles, flows through a large central cavity called the spongocoel, where filter-feeding occurs thanks to specialized collar cells (choanocytes).
After food particles are trapped and digested, cells called amebocytes distribute the nutrients throughout the sponge. The water then exits the body through the osculum, carrying away waste products and carbon dioxide from cellular respiration. The entire process allows sponges to perform essential functions like gas exchange, circulation, and excretion through the diffusion of substances between their cells and the water passing through.