Euphausiids, commonly known as krill, are small, shrimp-like crustaceans found in oceans worldwide. They play a crucial role in marine ecosystems, serving as a primary food source for various species, including whales, seals, and fish. Euphausiids are typically transparent and can grow up to 6 centimeters in length. These organisms thrive in cold, nutrient-rich waters, often forming large swarms. They feed on phytoplankton and are vital for the ocean's food web. Euphausiids also contribute to carbon cycling, as their waste helps transport carbon to deeper ocean layers, playing a role in regulating global climate.