Through a microscope, an Antarctic krill (Euphausia superba) resembles an alien creature from a science fiction movie. But in real-life size, these pink and semitransparent crustaceans are really small—measuring just 2 inches long on average. Their size belies their enormous role in the health of the Southern Ocean’s ecosystem, where krill are the undisputed center of the Antarctic marine food web. They travel in swarms—tens of thousands in a square yard—and are a main food source for a variety of the region’s best-known animals, from whales and seals to penguins. Even animals that don’t eat them directly, such as leopard seals and orcas, subsist on creatures that do. These relatives of shrimp also feed on carbon-capturing algae at the ocean’s surface, dropping their carbon-filled waste near the seafloor, which reduces carbon in the atmosphere and helps to reduce the effects of climate change. For all of these reasons, The Pew Charitable Trusts has worked for years to safeguard krill and their environment.