Krill Information
Antarctic Krill
Antarctic Krill (Euphausia Superba) is primarily composed of Water, Protein and Fat. However when the moisture has been removed from krill the leftover product is high in protein and lipids, making krill highly nutritious and beneficial as a food.
What are krill?
Krill are a small shrimp-like crustaceans that can be found in the Antarctic Ocean. It is the most important zooplankton species associated with the sea ice and plays a key role in the Antarctic food chain. Euphausia superba make up an estimated biomass of between 135 and 500 million tons, roughly twice that of humans.
Krill occur in all oceans of the world. They are considered keystone species near the bottom of the food chain because they feed on phytoplankton and to a lesser extent zooplankton, converting these into a form suitable for many larger animals for whom krill makes up the largest part of their diet. Of the krill, over half is eaten by whales, seals, penguins, squid and fish each year, and is replaced by growth and reproduction. Most krill species display large daily vertical migrations, thus providing food for predators near the surface at night and in deeper waters during the day.
Behaviour of Krill
Most krill are swarming animals; the size and density of such swarms vary greatly depending on the species and the region. Of Euphausia superba, there have been reports of swarms of up to 10,000 to 30,000 individuals per cubic meter. Swarming is a defensive mechanism, confusing smaller predators that would like to pick out single individuals. This behavior has given rise to the plural classification, a plague of krill.
Krill typically follow a diurnal vertical migration meaning that they spend the day at greater depths and rise during the night towards the surface. The deeper they go, the more they reduce their activity, apparently to reduce encounters with predators and to conserve energy. Some species, such as Antarctic krill also form surface swarms during the day for feeding and reproductive purposes even though such behaviour is dangerous because it makes them extremely vulnerable to predators. Dense swarms may elicit a feeding frenzy among fish, birds and mammal predators, especially near the surface.
Krill normally swim at pace of a few centimetres per second using their swimmerets for propulsion. Their larger migrations are subject to the currents in the ocean. When in danger, they show an escape reaction called lobstering—flicking their caudal structures, the telson and the uropods, they move backwards through the water relatively quickly, achieving speeds in the range of 10 to 27 body lengths per second, which for large krill such as E. superba means around 3 ft/s. Their swimming performance has led many researchers to classify adult krill as micro-nektonic lifeforms, i.e., small animals capable of individual motion against (weak) currents.