Animal · Antarctica, South Georgia
Antarctic krill
Euphausia superba — the name this animal has in the language scientists everywhere share.
Antarctic krill is a shrimp-like animal about six centimetres long that swims in swarms so dense the water turns pink. Almost everything that lives in the Southern Ocean depends on this one small creature.
Picture credit: Krill666.jpg (CC BY-SA 3.0) · Dr. Wayne Trivelpiece (Public domain) · Wikimedia Commons
Where does the Antarctic krill live?
Home: the cold open water and the under-ice world of the Southern Ocean.
In the wild it lives in these countries: Antarctica, South Georgia.
Conservation status from the IUCN: not in danger.
The short profile
Fully grown: up to 6 cm long. It weighs about 0 002 kilograms. On the menu: tiny creatures it filters out of the water.
The story behind it
A single krill weighs no more than two grams, but they gather in swarms with tens of thousands of animals in every cubic metre of water, and a swarm can stretch for kilometres. They feed with a basket of bristly legs that strains tiny algae out of the seawater, and in spring they scrape the green film of algae off the underside of the sea ice with the same comb. Blue whales, crabeater seals, penguins and albatrosses all eat them, which is why people call krill the food that holds the Southern Ocean together. Krill glow: small organs on the body send out a blue-green light that probably helps them stay together in the dark. Because their shell cannot stretch, they moult again and again, and when food is short they can moult into a smaller body instead of a bigger one. Each summer, fishing boats take krill for fish farms and food supplements, so catches are limited by an international agreement. Scientists watch krill closely, because sea ice that forms later in the year leaves the young with less to eat.
Find it on the globe
Antarctic krill is there as a tiny animated figure that breathes and looks around. From far away the planet is only a blue ball; detail arrives as you zoom in, and this one appears once you are close enough. Open it on the globe.
It sits at its real coordinates, not near them — the same numbers listed in the facts above. Switch off the layer for this kind of place and it disappears again; the buttons for that are down the right-hand edge.
Questions children ask
What does Antarctic krill look like?
It looks like a small, see-through shrimp with black eyes and a green line inside, which is the algae it has just eaten. Grown animals reach about six centimetres and weigh around two grams.
Where does Antarctic krill live?
It lives all the way around Antarctica in the Southern Ocean, with especially large swarms in the Scotia Sea near South Georgia. The animals move up and down through the water each day and often stay close to the sea ice.
Why is krill so important?
Krill turns the tiny algae of the sea into food that bigger animals can catch, so whales, seals, penguins and seabirds all eat it. Add every krill in the Southern Ocean together and their weight runs into the hundreds of millions of tonnes.
Where these numbers come from
Every figure on this page was checked against public reference sources before publication. Where sources genuinely disagree, the text says so.
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