The transfer of energy from organism to organism forms a series called a food chain. All the possible feeding relationships that exist in a biome make up its food web. In the ocean, as elsewhere, the food web consists of producers, consumers, and decomposers. These three types of organisms transfer energy within the oceanic environment.

Phytoplankton are the primary producers in the oceans. They produce organic materials from inorganic chemicals and outside sources of energy, primarily the Sun.

Zooplankton and other animals are consumers. Zooplankton that eat only plants are primary consumers in the oceanic food web. Secondary consumers eat the plant-eaters. They include the baleen whale and zooplankton that eat other zooplankton. Tertiary consumers are the predators, like tunas and sharks. Humans also fall into this category. Humans are also omnivores, organisms that eat both plants and animals.

Decomposers feed on dead organic...