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What is Antarctic Krill?

Michael Anissimov
Michael Anissimov
Michael Anissimov
Michael Anissimov

Antarctic krill (Euphanasia superba) are a species of krill found in the Southern Ocean which surrounds Antarctica. They are distinct for being among the species with the world's greatest total biomass, probably just second to humanity, which surpassed them sometime around 2007. Their total biomass is approximately 500 million tonnes. Antarctic krill are omnipresent in the waters around Antarctica, where they enjoy relatively little competition from animals of similar size. Krill are small crustaceans.

Like many other planktonic crustaceans, krill make up their living by gobbling up little bits of phytoplankton, the plants of the sea. Whereas insects are the dominant arthropods on land, crustaceans such as Antarctic krill are the arthropod kings of the sea. They have numerous adaptations which have helped them secure their place as one of the world's species with the most biomass, including massive compound eyes, a "feeding basket" for filter feeding, a muscular telson (tail) that can be used to rapidly "lobster" away from predators, bioluminesence (the utility of which is not fully understood), swarming behavior, the ability to shrink in size from one molt to the next (to compensate for conditions of low nutrients), and many others.

Antarctic krill feed on the underside of icebergs.
Antarctic krill feed on the underside of icebergs.

In the Antarctic, Antarctic krill have been observed feeding on algae on the undersides of freezing cold icebergs or the ice sheet. Their density can approach 10,000-30,000 individuals per cubic meter. Living up to six years, Antarctic krill can grow as large as 6 cm (2.4 in), and weigh up to 2 g (0.7 oz). They are the most important prey item of the Antarctic ecosystem, consumed by fur seals, Leopard Seals, Crabeater Seals, whales, icefish, squid, penguins, albatross, and hundreds of other bird species. Due to their abundance and ecological importance, they are one of several planktonic species sometimes referred to as a "potato chip of the sea."

Antarctic krill are found in the frigid region after which they are named.
Antarctic krill are found in the frigid region after which they are named.

Unlike many other marine crustaceans, the legs of Antarctic krill do not form a jaw or claw-like structure, instead having greater similarity to the simplistic legs of many insects. To reproduce, males attach spermatophores to the area around the female genitals, which periodically releases 6,000 - 10,000 eggs. These fertilized eggs slowly descend, over the course of weeks, to kilometers below the surface, where they develop into juvenille Antarctic krill that swim back to the top. This general pattern has likely been the same for hundreds of millions of years.

Occasionally, Antarctic krill is captured by fisherman and compressed into blocks which can be used for cooking. However, yield is not nearly as high as many other crustaceans and fish, due partially to the fact that their shells contain fluorides, which can be toxic in high concentrations. Also, capturing them requires fine-grained meshes, which have high drag and frequently break. Though Antarctic krill are extremely numerous, most humans find them unexciting to eat. For now, they'll have to serve as dinner for hundreds of other species instead.

Frequently Asked Questions

What exactly is Antarctic krill and why is it important?

Antarctic krill are small, shrimp-like crustaceans found in the Southern Ocean. They play a crucial role in the Antarctic ecosystem as a key food source for whales, seals, penguins, and other marine species. Krill also help to sequester carbon by feeding on phytoplankton and then excreting it deep in the ocean.

How large is the Antarctic krill population?

The Antarctic krill population is vast, with estimates suggesting a biomass of around 379 million tonnes, according to a study published in the journal "Limnology and Oceanography." This makes them one of the most abundant animal species on the planet and a vital component of the ocean's food web.

What do Antarctic krill eat and how do they contribute to the carbon cycle?

Antarctic krill primarily feed on phytoplankton, microscopic plants that absorb carbon dioxide during photosynthesis. Krill contribute to the carbon cycle by consuming phytoplankton and then releasing carbon-rich waste at depth, which can be sequestered in the deep ocean for long periods, thus playing a role in mitigating climate change.

How is climate change affecting Antarctic krill populations?

Climate change poses a significant threat to Antarctic krill. Warming waters and decreasing sea ice affect krill habitat and food availability. Research indicates that changes in sea ice patterns can reduce the algae that krill feed on, potentially leading to declines in their populations and impacting the species that rely on them for food.

What methods are used to sustainably manage Antarctic krill fisheries?

Sustainable management of Antarctic krill fisheries involves setting precautionary catch limits and monitoring krill populations. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) oversees these efforts, using scientific data to adjust quotas and ensure the ecosystem remains balanced and the krill population remains healthy.

Can humans consume Antarctic krill, and what are the benefits?

Yes, humans can consume Antarctic krill, which are harvested for their oil and protein. Krill oil is rich in omega-3 fatty acids and antioxidants, offering potential health benefits such as reducing inflammation and improving heart health. However, it's essential to ensure that krill products come from sustainable sources to protect the Antarctic ecosystem.

Michael Anissimov
Michael Anissimov

Michael is a longtime AllThingsNature contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

Learn more...
Michael Anissimov
Michael Anissimov

Michael is a longtime AllThingsNature contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

Learn more...

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    • Antarctic krill feed on the underside of icebergs.
      By: Goinyk Volodymyr
      Antarctic krill feed on the underside of icebergs.
    • Antarctic krill are found in the frigid region after which they are named.
      By: axily
      Antarctic krill are found in the frigid region after which they are named.