Antarctic Krill

Antarctic krill is a small, shrimp-like crustacean found in the Southern Ocean surrounding Antarctica, and despite its small individual size, typically only a few centimetres long, it is one of the most abundant animal species on Earth by total biomass, forming massive swarms that can stretch for kilometres and contain billions of individuals. It feeds mainly on microscopic phytoplankton that bloom in the nutrient-rich waters around Antarctica, and in turn it forms the foundation of the Southern Ocean food web, serving as the primary food source for a huge range of animals including baleen whales, seals, penguins and many fish species. Antarctic krill undertake daily vertical migrations, moving toward the surface to feed at night and retreating to deeper, darker water during the day to avoid predators, and populations can fluctuate significantly depending on sea ice conditions, which affect the algae the krill depend on. The species is also commercially harvested in large quantities for fishmeal, aquaculture feed and dietary supplements, raising ongoing concern among scientists about the effect of that harvest on the wider Southern Ocean ecosystem.