What Are Krill?

Antarctic krill are tiny, little-known crustaceans that serve as the "bread and butter" for hundreds of species. For many marine mammals and seabirds, from the blue whale to the albatross, krill are by far the most important food in their diet.

Encompassing more than 80 species of open-ocean creatures scientifically classified as Euphausiids, Antarctic krill are about 2 ½ inches long (6 centimeters) and weigh 0.07 ounces or roughly two grams. Yet these little creatures are distinctive on several scores. Krill are one of the world's most abundant multi-celled animals, producers of the most powerful enzymes yet discovered to break down proteins, and collectively thought to be one of the largest aggregations of marine life on the planet.

In the water, krill have an exotic appearance, with a translucent, reddish shell and large black eyes. Krill spend most of their 5-7 year life span in huge schools or "swarms," living in concentrations so dense and vast that they cover kilometers in every direction with as many as 30,000 krill per cubic meter. Estimates of the total weight of Antarctic krill range from 50 to 500 million metric tonnes.

Why Are We Concerned About Krill?

Increasingly, krill's natural predators, such as penguins and seals, must now compete for their prey with industrial fishing vessels that often trawl in coves and near-shore waters, close to rookeries and feeding grounds. Recent field research shows that the demand for krill by land-based species has begun to exceed supply in certain areas of the southwest Atlantic.

Some scientists warn that the potential now exists for localized depletion of krill at levels that could seriously impact the entire southern marine ecosystem. These concerns have been made more urgent by global warming and by new technology that allows krill to be caught and pumped continuously out of the water and onto a vessel, where it can be processed immediately to prevent spoilage.