Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract; such as through eating or drinking. In single-celled organisms ingestion takes place by absorbing a substance through the cell membrane. Ingestion can also refer to a mechanism picking up something and making it enter an internal hollow of that mechanism, e.g. "a grille was fitted to prevent the pump from ingesting driftwood".