Antarctic krill are small shrimp-like crustaceans at the heart of the Southern Ocean food web. Changes in sea ice and a growing krill fishery are major concerns for the ecosystem.
Interesting facts
- Krill swarms can be so dense they turn the sea red and are visible from space.
- They glow with bioluminescent organs.
- Krill can shrink when food is scarce.
- They feed on algae scraped from the underside of sea ice.
- Whales, seals, penguins, fish and seabirds all depend on them.
- Krill faecal pellets carry carbon to the deep sea.
Behaviour
Krill form huge swarms and migrate vertically, rising to feed at night and sinking by day.
Breeding and young
Females release thousands of eggs, which sink to depth before larvae rise to the surface.
Threats and conservation
Sea-ice loss due to climate change, ocean acidification and fishing for fishmeal and supplements.
Where to see it
- Visible in swarms on Antarctic expedition cruises, and in whale feeding areas
Status source: IUCN Red List. Profile last reviewed September 2026.
Antarctica Cruise Guide: Penguins, Whales and the Drake Passage
