planktonfeeding

Planktonfeeding describes the feeding strategies of organisms that rely primarily on plankton for nourishment. Plankton includes phytoplankton, which are photosynthetic, and zooplankton, which are small animals and protozoa. Planktivores may consume one or both components, depending on availability and habitat. In aquatic systems, plankton is often suspended in the upper water column, providing a concentrated food source for many species.

The main modalities of plankton feeding are filter feeding, suction feeding, and ambush or ram feeding. Filter feeders draw in water and strain out plankton using specialized structures such as baleen plates in baleen whales, gill rakers in many fish and crustaceans, or mucus nets produced by some tunicates and larvaceans. Suction feeders rapidly expand their mouths to draw in water and prey, then trap the prey with their mouthparts or teeth. Ambush feeders, including some jellyfish and gelatinous zooplankton, capture passing plankton with tentacles or filtering appendages as they drift.

Adaptations for plankton feeding include specialized mouthparts, filtering membranes, and techniques to manage buoyancy and swimming speed. These adaptations allow organisms to exploit the abundant but distributed resource of plankton, often in nutrient-rich surface waters or convergent feeding zones created by currents and tides.

Ecologically, plankton feeders play a crucial role in transferring energy from primary production to higher trophic levels. They influence plankton community structure, drive seasonal cycles, and connect a wide range of marine and freshwater food webs. Notable plankton-feeding groups include baleen whales, small pelagic fish, krill, copepods, jellyfish, and larvacean filter feeders.