What is the cell in sponge that digest food?

The cell in sponges that digest food are called choanocytes (singular choanocyte). Choanocytes are specialized cells that line the internal canals and chambers of sponges. These cells have a collar of microvilli, which are tiny hair-like projections that help to capture food particles from the water.

Sponges are filter feeders, and they use their choanocytes to capture and digest food particles from the water. The choanocytes create a current of water through the sponge's body by beating their flagella, which are whip-like structures that project from the collar of microvilli. This current of water carries food particles, such as plankton and bacteria, into the sponge's body where they are captured by the choanocytes.

The choanocytes then engulf the food particles by phagocytosis, which is the process of engulfing solid particles by a cell. The food particles are then digested within the choanocytes' lysosomes, which are organelles that contain digestive enzymes. The nutrients from the digested food particles are then released into the sponge's body and used by the sponge to grow and repair its cells.