A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton.[1][2] Planktivorous organisms encompass a range of some of the planet's smallest to largest multicellular animals in both the present day and in the past billion years; basking sharks and copepods are just two examples of giant and microscopic organisms that feed upon plankton.[3]
Planktivory can be an important mechanism of top-down control that contributes to trophic cascades in aquatic and marine systems.[4][5] There is a tremendous diversity of feeding strategies and behaviors that planktivores utilize to capture prey.[6][4][7] Some planktivores utilize tides and currents to migrate between estuaries and coastal waters;[8] other aquatic planktivores reside in lakes or reservoirs where diverse assemblages of plankton are present, or migrate vertically in the water column searching for prey.[9][5][10][11] Planktivore populations can impact the abundance and community composition of planktonic species through their predation pressure,[12] and planktivore migrations facilitate nutrient transport between benthic and pelagic habitats.[13]
Planktivores are an important link in marine and freshwater systems that connect primary producers to the rest of the food chain. As climate change causes negative effects throughout the global oceans, planktivores are often directly impacted through changes to food webs and prey availability.[14] Additionally, harmful algal blooms (HABs) can negatively impact many planktivores and can transfer harmful toxins from the phytoplankton, to the planktivores, and along up the food chain.[15] As an important source of revenue for humans through tourism and commercial uses in fisheries, many conservation efforts are going on globally to protect these diverse animals known as planktivores.[16][17][7][18]