What Are Krill?

Krill are small shrimp like crustaceans that live in the ocean with large black eyes and are usually around only 2 inches (5 centimetres) on average in length. The digestive system of many species of krill is transparent and visible to the human eye. They can survive up to 200 days without food, and typically, they can live between 5 and 10 years. Krill are one of the most abundant and successful animal species on earth. Scientists estimate that the total weight of all the Antarctic krill is more than the total weight of all humans on Earth! Which is why although tiny creatures they are, they represent a giant role in our global marine food chain and ecosystem. These small, shrimp-like crustaceans are essentially the fuel that runs the engine of the Earth’s marine ecosystems.

Krill feed on algae, phytoplankton, microscopic, single-celled plants that drift near the ocean’s surface and live off carbon dioxide and the sun’s rays where some krill have even been observed eating other krill. They in turn are the primary diets of literally hundreds of different animals and species from fish, birds, squids and whales.

Without the existence of krill, most of the life forms in the Antarctic would disappear.

There are 85 known species of Krill. Euphausia superba are the most common species of krill and are found swimming in the Antarctic. Krills are broken down into two families: Euphausiidae and Bentheuphausia ampblyops.

Euphausiidae are found swimming closer to the surface of the ocean (which make them easier for biologist to study) while the lesser known primitive Bentheuphausia ampblyops are found living in deeper waters (below 3,000 feet).

Female krill can lay thousands of eggs seasonally and again depending on species will either carry her eggs (which can take up to 1/3 her body mass) or drop them at which they sink leaving the baby krill to swim up on its own once it hatches.

Today, between 200,000 to 400,000 tons of Krill are caught annually. Krill are not common food for many people although in Japan and Russia, krill is used for human consumption and is known as okiami (オキアミ) in Japan. Krill has also been harvested as a source of nutritional food for both humans and domestic animals, and sold as krill oil, which contains high amounts of Omega-3 fatty acids which some says are better than fish oil.

Alarmingly, like many other sea dwelling creatures, the number of Krill is declining. There are recent studies (November 2004) that show their numbers may have dropped by 80percent since the 1970s. Scientists believe that the primary reason for this is likely to be caused by ice cover loss caused by global warming. This ice loss removes a primary source of food for krill - ice-algae and phytoplankton. Also, the thinning of our ozone layer increases the amount of ultraviolent light that reaches the Antarctic and serves as another threat to the Krill’s survival. 

Some believe that the decline in Krill is one of the reasons many Antarctic animals such as penguins and Baleen whales are also declining in number.