How do animal sponges obtain food from water?

Sponges (phylum Porifera) are primarily filter feeders that obtain nutrients by processing large volumes of water through a specialized internal system.1

The Feeding Process

• Water Circulation: Sponges maintain a continuous flow of water using the movement of flagella located on specialized cells called choanocytes (collar cells). This current draws water in through small pores (ostia) and expels it through larger openings called oscula.12
• Food Capture: As water passes through the sponge, choanocytes capture suspended food particles, including bacteria, microorganisms, and organic debris. Sponges may also absorb dissolved organic substances directly.1
• Digestion: Once captured, food particles are transferred by specialized amoebocytes (thesocytes) throughout the sponge body. Digestion occurs intracellularly within both the choanocytes and thesocytes.1

While most sponges rely on this filter-feeding mechanism, some deep-water cladorhizid sponges are exceptions; they lack a water-current system and instead function as carnivores, capturing prey using filaments that cover their bodies.12