What is a "krill"?

A krill is a small, shrimp-like crustacean that forms a vital part of the marine food chain. They are found in large numbers in cold ocean waters and serve as a key food source for many marine animals, including whales, seals, penguins, and fish. Krill play a significant role in the transfer of energy from phytoplankton (microscopic plants) to higher trophic levels. They feed on phytoplankton and zooplankton and, in turn, are consumed by larger predators. Krill are known for their swarming behavior, forming dense aggregations that can be seen from the surface of the water. They have a high nutritional value and are also harvested by humans for various purposes, including as a food source and as a source of omega-3 fatty acids.