Krill are small, shrimp-like crustaceans that are a vital part of the marine food web, serving as a primary food source for many species of whales, seals, fish, and birds. They are found in all the world's oceans and are particularly abundant in the Southern Ocean around Antarctica. Krill are filter feeders, using their distinctive legs to collect phytoplankton and other microscopic organisms from the water. They are also known for the bright red pigments in their bodies, which come from the tiny algae they consume. Krill are harvested commercially for their oil and as a source of protein in animal feed.