Amazing Antarctic Krill Fish – A Keystone Species

Krill fish

Last updated on September 15th, 2022 at 01:26 pm

Krill fish is the most abundant animal in the world. It is a shrimp-like crustacean that lives in the oceans and plays an important role in the food chain.

Over the last 20 years, krill populations have collapsed by 80% because of overfishing and climate change. The ecosystem is currently at risk as we’re seeing a large reduction in krill numbers. As krill are eaten by larger animals, they are converted into energy, biomass, and other resources that make their way through several levels of the food chain.

Krill fish are found in the world’s oceans, and they are rich in omega-3 fatty acids. They serve as food for other marine organisms like fish, whales, and seals. Most importantly, krill are a popular source of food for baleen whales such as blue whales, fin whales, and humpback whales.

What is a krill fish (Krill definition)?

Krill fish

Any member of the crustacean order Euphausiacea is known as a krill fish. Crabs, lobsters, crayfish, and shrimp are also in the same animal class as woodlice and crayfish. About 82 species of krill have been discovered. Their life expectancy is up to 5 years and they grow up to 6cm in length.

Origin and description

The name “krill” originates from the Norwegian word for shrimp. Krill consists of two main species: Antarctic krill (Euphausia superba) and Pacific krill (Euphausia pacifica).

Krill are small crustaceans found in the ocean and they feed on phytoplankton. They are a type of zooplankton, which means they live in the water column and cannot swim against a current.

Krill are a rich source of protein, oil, and vitamins for humans. Krill oil is rich in the omega-3 fatty acids EPA and DHA, which can be used as an alternative to fish oil due to the taste and smell of krill oil being less offensive

They are a major part of the food chain and an important food source for whales, birds, and seals.

Krill fish can grow to be about 5 inches (12.7 cm) long and weigh about 1 ounce (28 g). They are crustaceans and are related to crabs and lobsters.

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They live in the water, but they also come onto land at times, especially during the breeding season. When this happens, they leave a trail of green feces behind them. These trails are called “krill tracks”. They eat plant material and tiny animals like planktons.

Species profile

Krill fish

Krill are euphausiids, and the name is derived from the German word “krill” for “small fry” (diminutive of “krail”, meaning “sprinkle”), which is what this animal was called by fishermen in the 19th century. They are small, shrimp-like sea creatures that live in all of the world’s oceans. They are found in water as shallow as 10 centimeters (4 inches) and as deep as 5,000 meters (16,400 feet).

The Antarctic krill (Euphausia superba) is a large species of krill found in the Southern Ocean. It is a keystone species and an important food organism for whales, seals, leopard seals, fur seals, squid, and fish. The Antarctic krill fishery is one of the largest in the world, with annual catches exceeding one million tonnes.

However, it is not a sustainable fishery and the krill population has been declining for many years. The main reasons for this are thought to be climate change and overfishing.

Krill form the basis of the oceanic food chain as they are a primary food source for many of the ocean’s predators. Due to their abundance, krill make up a large part of the biomass of the oceans and are often referred to as “the whales’ lettuce”.

In German, “krill” is known as “Meeräsche”, which literally means “sea rabbit”. The name originates from the resemblance of their shape to that of a rabbit.

Scientific name of krill fish

Euphausiacea is the scientific name of krill fish. The term euphausia means light or illumination in Latin and Greek. Krill probably got its name for its bioluminescent glow.

These crustaceans are in the Malacostraca family, which has over 40,000 species

Where does krill live?

Krill lives in the ocean. They have a shell on their back to protect them from predators. There are other animals that live in the ocean too. One of them is the shark.

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When krill is young, it lives in the plankton, but as they grow they move towards the top of the water. Krill live in all oceans, seas, and freshwater lakes.

Krill fish size and weight

The largest krill can grow up to 6 centimeters in length. The smallest ones are just 0.004 inches long, and the average ones are about 1–2 centimeters (0.4–0.8 in) long as adults, it weighs up to 2 grams (0.071 oz), and can live for up to six years.

Krill fish tank size

Krill fish tanks sizes can vary depending on the amount of water you want to use in your tank and the size of the krill fish you wish to keep within your tank. A typical tank size would be around two to three gallons.

A krill fish tank is a great addition to any home. Most people choose to put their krill fish tank in their living room. This is because the living room is the place where most of us spend most of our time at home, so it is easier for us to take care of them.

You should consider using a tank that has a capacity of up to 2 gallons for each krill fish. The size is proportional to the number of krill fish you are going to put in your tank.

Krill fish tankmates

Krill are a perfect choice for any home aquarium. They are ideal tank mates due to their low maintenance and good compatibility with other fishes. They don’t need a lot of swimming space, and they live longer than most fish.

They feed on the leftovers in the tank, preferably algae wafers that are easy to find in the store. The dark color of their meat is easily covered with decorations, so they are good in any scale.

A trio of krill fish can live together in an aquarium. Koi fish and koi carp are considered highly recommended tank mates.


Krill fish

The male deposits a sperm sack at the genital opening (thelycum) of the female during the mating season, which varies by species. Several thousand eggs may be laid by the females in their ovary, accounting for up to one-third of their total body mass. A Krill can have several broods during a single breeding season, with the interbrood interval lasting for some weeks.

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There are two forms of spawning mechanism used by Krill. A total of 57 species are known from the genera Bentheuphausia, Euphausia, Meganyctiphanes, Thysanoessa, and Thysanopoda that broadcast their eggs into the water, where they disperse and live on their own.

In general, these species hatch at the nauplius 1 stage, but recently, there have been reports that these species can also hatch at the metanauplius or even the calyptopis stages.

The other 29 species of other genera spawn in sacs, where the ovaries are attached to the rearmost pairs of thoracopods until they hatch as metanauplii, although in some species, such as Nematoscelis difficilis, the eggs may hatch as nauplius or pseudometanauplii.

Krill fish life span

Krill from high-latitude areas can live up to six years (e.g. Euphausia superba), whereas those from mid-latitude areas (e.g. Euphausia pacifica) only live for two years.

Species in subtropics or the tropics live shorter than tropical species. A good example is Nyctiphanes simplex, which usually lives for six to eight months.

Moulting in krill fish

A specimen becomes moulded when its rigid exoskeleton can no longer support it. Moulting occurs more often in young animals since they grow faster. Moulting occurs at varying rates according to species, and even within a species, it is influenced by external factors such as latitude, water temperature, and food availability.

Subtropical species, like Nyctiphanes simplex, moult every four to seven days on average: larvae change every four days, while juveniles and adults change every six days on average. The inter-moult period for E. superba in the Antarctic sea varies from 9 to 28 days, depending on the actual temperature level between 1 and 4 degrees Celsius (30 and 39 degrees Fahrenheit).

For Meganyctiphanes norvegica in the North Sea, the inter-moult period also varies between 9 and 28 days, but at a temperature between 2.5 and 15 degrees Celsius (36.5 and 59.0 degrees Fahrenheit).Molting is also an option when the exoskeleton becomes too large; E. superba reduces its body size when enough food is not available.

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As an adaptation to abnormally high water temperatures, E. pacifica has also shown shrinkage as well, a species that occurs in the Pacific Ocean from polar to temperate zones. Species of krill from temperate zones have also been predicted to shrink.

Role of krill fish in the food chain

Krill fish

Krill feed on phytoplankton, which is a microscopic, single-celled plant that drifts near the ocean’s surface and lives by absorbing carbon dioxide and solar radiation from the sun.

As a result, they are ingested by literally hundreds of different species, from fish to birds to baleen whales.

In simplicity, krill fish plays an imperative role in ocean life.

Importance of krill to the Antarctic Ecosystem

Among the 85 species of known krill, Antarctic krill (Euphausia superba) are pink and opaque. In the waters around Antarctica, they are thought to number between 125 million tons and 6 billion tons.

During certain times of the year, krill swarms can be seen from space since they are so dense and widespread. Despite being heavily hunted, Antarctic krill can live up to 10 years.

The Antarctic Ocean belongs to a diverse community of species that spend most of their time avoiding predators, some 320 feet below the surface. They drift upwards from the bottom of the water column toward the surface at night in search of phytoplankton.

Recent studies have found that Antarctic krill stocks may have declined by 80 percent since the 1970s. Global warming is believed to be responsible for these declines in part. As a consequence, ice-algae, which is a primary source of food for krill, is removed.