When an organism is unable to make its own food and must rely on plants or other organisms for sustenance, it is said to be heterotrophic.
Heterotrophic nutrition comes in a variety of forms.
Internalization (ingestion) and internal digestion of liquids or solid food particles are features of holozoic nutrition, which is a kind of heterotrophic nutrition.
Saprophytic feeding is a chemoheterotrophic extracellular digesting process in which deteriorated (dead or waste) organic molecules are broken down.
It's present in saprotrophs and is often associated with fungi (like Mucor) and soil bacteria.
In parasitic nutrition, an organism lives on the surface of another organism's body or inside its body.
The parasite gets its nutrients directly from the host's body.