Krill

Krill are small, shrimp-like crustaceans in the order Euphausiacea. They typically range from about 1 to 6 centimeters in length and occur in oceans worldwide, with large populations in the Southern Ocean. Krill form vast swarms that can be visible from space and are a crucial link in marine food chains.

Most krill feed by filtering tiny phytoplankton and other microscopic particles from seawater, though some species consume small zooplankton or detritus. They perform diel vertical migration, rising toward the surface at night to feed and descending to deeper waters by day to avoid predators. Krill are known for their high fatty-acid content and play a major role in the transfer of energy from primary producers to higher trophic levels.

Reproduction in krill involves releasing eggs into the water, with fertilized eggs developing into free-swimming nauplius larvae that molt through several stages before reaching adulthood. Life spans vary by species and environmental conditions, and populations can respond to changes in sea temperature, ice cover, and food availability.

Ecologically, krill are a keystone species in many ecosystems. They provide essential prey for whales, seals, penguins, fish, and squid, supporting both natural communities and commercial fisheries. Humans harvest krill for products such as krill oil, animal feed, and aquaculture ingredients.

Notable species include the Antarctic krill (Euphausia superba) and the northern krill (Euphausia pacifica). Conservation and management of krill stocks are influenced by climate change and regional fisheries regulations, given their sensitivity to sea-ice dynamics and ocean productivity.