How do sponges process their food?

Sponges are simple multicellular organisms belonging to the phylum Porifera. They are known for their unique and efficient food processing mechanism called filter feeding. Here's a detailed explanation of how sponges process their food:

1. Water Flow:

- Sponges have a unique body structure with numerous pores called ostia that allow water to enter the sponge's body.

- The beating of specialized flagellated cells called choanocytes creates a water current that draws water through the ostia into the sponge's internal cavity.

2. Trapping Food Particles:

- As water flows through the sponge's body, it passes through a complex network of internal channels and chambers.

- Specialized cells called collar cells or choanocytes line these channels and chambers. Each choanocyte has a collar and a long whip-like flagellum.

- The beating of the flagellum creates a water current that draws food particles toward the choanocyte's collar.

- The collar is covered in mucus that traps food particles, such as plankton, bacteria, and other microorganisms, from the water.

3. Digestion:

- The trapped food particles are then engulfed by the choanocytes through phagocytosis.

- Inside the choanocytes, the food particles are digested in vacuoles.

- Some sponges also have symbiotic relationships with bacteria living within their tissues. These bacteria assist in the digestion of food particles.

4. Absorption and Distribution:

- The digested food particles are absorbed and distributed throughout the sponge's body by specialized cells called amoebocytes.

- Amoebocytes move freely within the sponge's mesohyl (the gelatinous layer between the outer and inner cell layers) and transport nutrients to different parts of the sponge.

5. Expulsion of Waste:

- Undigested waste materials and excess water are expelled from the sponge through larger openings called oscula (singular osculum).

- The oscula are located at the top or sides of the sponge's body and allow the outflow of waste.

By continuously filtering water through their bodies, sponges obtain a constant supply of food and oxygen while simultaneously expelling waste. This unique feeding strategy enables sponges to survive in various aquatic environments, including shallow coastal waters, deep sea floors, and even in freshwater habitats.