Question

Describe how sponges feed.

Short answer

The sponges feed by a unique method called filter-feeding. They filter out food particles present in the surrounding water when the water passes through the cavity in their body. This cavity is called a spongocoel.

The water then flows out of the body by an opening called an osculum. Complex sponges have more than one osculum and canals.

Step-by-step solution

Sponges

Sponges are multicellular organisms that belong to the phylum Porifera. Water is absorbed by the sponge through its ostium, which are minute pores on the sponge body surface.

Sponges consist of a jelly-like mesohyl between the thin layers of their cells. Sponges can be found in various environments, from shallow intertidal zone and coral reefs to the deep sea.

Cells employed for feeding in sponges

Sponges use choanocytes to trap microorganisms with a diameter of less than 0.5 microns. Sponge feeding is mainly carried out by choanocytes. The nutrient particles larger than ostia (pores) are then engulfed by the sponge by phagocytosis.

The amoebocytes cells receive food from the choanocytes and digest it, then transfer the nutrients to the respective cells.

Feeding process in sponges

To fulfill the nutrient supply, the sponges use the mechanism of filter-feeding to obtain nutrition from the water flowing through them. The sponge absorbs water through its ostium, which are microscopic pores on its body surface.

The water is drawn into the pores of the sponges with the help of collar cells that move like a flagellum. Collar cells line the sponge passages and chambers, creating a flow by swinging their back and forth in unison, causing the water to flow into the sponge.

The pores then absorb the nutrients flowing through the water and remove the excess water from the opening, called the osculum. Thus, sponges perform the feeding mechanism called filter-feeding and use cells like choanocytes to absorb nutrients from the water flowing through the ostia.