Order Euphausiacea refers to a group of marine animals commonly known as krill, which form a vital part of the ocean's food chain. Synonyms for Order Euphausiacea include euphausiids, krill shrimp, and simply krill. These tiny crustaceans are an important food source for many aquatic creatures, including whales, penguins, and various fish species. Krill are also commercially harvested for use in dietary supplements and as a source of food for humans. The ecological importance of krill cannot be overstated, as they play a crucial role in maintaining the balance of the world's oceans and the planet's overall biodiversity.