* Heterotrophs are organisms that cannot produce their own food. They must obtain their energy by consuming other organisms or organic matter.
* Animals are multicellular organisms that are classified as eukaryotes (having complex cells with a nucleus). They are incapable of photosynthesis, the process plants use to make food from sunlight.
Therefore, all groups of animals, from insects to mammals, are heterotrophs. They must eat plants, other animals, or organic matter to survive.