Amoeba catches food particles from the surrounding water by using its

Amoeba catches food particles from the surrounding water by using its pseudopodia.
 

Nutrition in Amoeba: Amoeba consumes food with the help of pseudopodia. Pseudopodia are temporary finger-like projections of the cell surface, which fuse over the food particle. This results in the formation of a food vacuole.

It is inside this food vacuole that complex substances are broken down into simpler ones. These are then diffused into the cell cytoplasm. The remaining undigested material is thrown out of the cell surface