Consumer

An organism that eats another organism is a consumer.

A rabbit obtains food by eating the grass, so some of the producer’s biomass passes to a consumer. The fox obtains food by eating the rabbit. Food chains begin with producers because the consumers depend, directly or indirectly, on the food that producers make.

Animals and other consumers cannot photosynthesise, so they obtain organic material by eating other organisms. A herbivore gains food and biomass by eating a producer. A carnivore may eat that herbivore, so it depends on the producer indirectly.

A consumer cannot make its food by photosynthesis. It obtains organic molecules by eating a producer or by eating another consumer whose food ultimately came from producers. Digestion breaks biomass into smaller soluble molecules, which can be absorbed and used in respiration or rebuilt into the consumer's own biomass.