Antarctic krill
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Subphylum: Crustacea Class: Malacostraca Order: Euphausiacea Family: Euphausiidae Genus: Euphausia Species: E. superba
Binomial name
Euphausia superba Dana, 1850

Antarctic krill are eaten by penguins(Euphausia superba^[a]) is a species of krill found in the Antarctic waters of the Southern Ocean. Antarctic krill are shrimp-like invertebrates that live in large schools, called swarms, sometimes reaching densities of 10,000–30,000 individual animals per cubic meter.^[1] They feed directly on minute phytoplankton, thereby using the primary production energy that the phytoplankton originally derived from the sun in order to sustain their pelagic (open ocean) life cycle.^[2] They grow to a length of 6 cm, weigh up to 2 g, and can live for up to six years. They are a key species in the Antarctic ecosystem and are, in terms of biomass, probably the most successful animal species on the planet (approximately 500 million tonnes).^[3] Antarctic krill Euphausia superba (Photo by Uwe Kils) GFDL larger images http://www. ... For other uses, see Scientific classification (disambiguation). ... For other uses, see Animal (disambiguation). ... Subphyla and Classes Subphylum Trilobitomorpha Trilobita - trilobites (extinct) Subphylum Chelicerata Arachnida - spiders,scorpions, etc. ... Classes Remipedia Cephalocarida Branchiopoda Ostracoda Maxillopoda Malacostraca The crustaceans (Crustacea) are a large group of arthropods (55,000 species), usually treated as a subphylum. ... // Subclasses Eumalacostraca Hoplocarida Phyllocarida See text for orders. ... Common name. ... Genera Euphausia Dana, 1852 Meganyctiphanes Holt and W. M. Tattersall, 1905 Nematobrachion Calman, 1905 Nematoscelis G. O. Sars, 1883 Nyctiphanes G. O. Sars, 1883 Pseudeuphausia Hansen, 1910 Stylocheiron G. O. Sars, 1883 Tessarabrachion Hansen, 1911 Thysanoessa Brandt, 1851 Thysanopoda Latreille, 1831 The family of the Euphausiidae is the largest family... Species Many, see text. ... This article does not cite any references or sources. ... James Dwight Dana (February 12, 1813 - April 14, 1895) was an American geologist, mineralogist and zoologist. ... For other uses, see Species (disambiguation). ... Families Euphausiidae Euphausia Dana, 1852 Meganyctiphanes Holt and W. M. Tattersall, 1905 Nematobrachion Calman, 1905 Nematoscelis G. O. Sars, 1883 Nyctiphanes G. O. Sars, 1883 Pseudeuphausia Hansen, 1910 Stylocheiron G. O. Sars, 1883 Tessarabrachion Hansen, 1911 Thysanoessa Brandt, 1851 Thysanopoda Latreille, 1831 Bentheuphausiidae Bentheuphausia amblyops Krill are shrimp-like marine... For other uses, see Antarctica (disambiguation). ... Superfamilies Alpheoidea Atyoidea Bresilioidea Campylonotoidea Crangonoidea Galatheacaridoidea Nematocarcinoidea Oplophoroidea Palaemonoidea Pandaloidea Pasiphaeoidea Procaridoidea Processoidea Psalidopodoidea Stylodactyloidea True shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. ... Invertebrate is an English word that describes any animal without a spinal column. ... School of juvenile herring - many fish have the opercula wide open for ram feeding and you can see the red gills The term swarm (schooling or swarming) is applied to fish, birds and insects and describes a behavior of an aggregation (school) of animals of similar size and body orientation... The cubic meter (symbol m³) is the SI derived unit of volume. ... Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of plankton. ... Global oceanic and terrestrial photoautotroph abundance, from September 1997 to August 2000. ... The pelagic zone is the part of the open sea or ocean comprising the water column, i. ... Animated map exhibiting the worlds oceanic waters. ... A life cycle is a period involving one generation of an organism through means of reproduction, whether through asexual reproduction or sexual reproduction. ... A centimetre (American spelling centimeter, symbol cm) is a unit of length that is equal to one hundredth of a metre, the current SI base unit of length. ... BIC pen cap, about 1 gram. ... A coral reef near the Hawaiian islands is an example of a complex marine ecosystem. ... An Antarctic krill, whose species comprises roughly 0. ...

Systematics

All members of the krill order are shrimp-like animals of the crustacean superorder Eucarida. Their breastplate units, or thoracomers, are joined with the carapace. The short length of these thoracomers on each side of the carapace makes the gills of Antarctic krill visible to the human eye. The legs do not form a jaw structure, which differentiates this order from the crabs, lobsters and shrimp. Common name. ... Orders Decapoda Euphausiacea Amphionidacea Eucarida is a superorder of crustaceans, comprising the decapods, krill and Amphionides. ... Thoracomer is a part of crustacean morphology Categories: Biology stubs ... The term carapace refers to a dorsal section of an exoskeleton or shell, in a number of animal groups. ... For other uses, see Gill (disambiguation). ... Thoracopod is the leg of crustacean used for walking, swimming feeding or filtration. ... A gnathopod is any leg-like appendage, specifically from a crustacean, that is at least partially modified to serve as a jaw. ... Suborders Dendrobranchiata Pleocyemata See text for superfamilies. ...

See also: Wikispecies:Euphausia superba

Life cycle

The eggs are spawned close to the surface and start sinking. In the open ocean they sink for about 10 days: the nauplii hatch at around 3000 m depth

The main spawning season of Antarctic krill is from January to March, both above the continental shelf and also in the upper region of deep sea oceanic areas. In the typical way of all euphausiaceans, the male attaches a sperm package to the genital opening of the female. For this purpose, the first pleopods (legs attached to the abdomen) of the male are constructed as mating tools. Females lay 6,000–10,000 eggs at one time. They are fertilized as they pass out of the genital opening by sperm liberated from spermatophores which have been attached by the males.^[4] krill hatching drawing uwe kils after marr gfdl File links The following pages link to this file: Antarctic krill User:Kils/Antarctic krill User:Kils/Antarctic krill/frozen Virtual University/Antarctic krill ... krill hatching drawing uwe kils after marr gfdl File links The following pages link to this file: Antarctic krill User:Kils/Antarctic krill User:Kils/Antarctic krill/frozen Virtual University/Antarctic krill ... This article is about the unit of length. ... Frog spawn Spawning is the production or depositing of eggs in large numbers by aquatic animals. ...  Sediment  Rock  Mantle  The global continental shelf, highlighted in cyan The continental shelf is the extended perimeter of each continent, which is covered during interglacial periods such as the current epoch by relatively shallow seas (known as shelf seas) and gulfs. ... Antennules Pereiopods Carapace Pleopods Uropods Telson The body of a decapod crustacean is made up of nineteen body segments grouped into two main body parts, the cephalothorax and the abdomen. ... In most birds and reptiles, an egg (Latin ovum) is the zygote, resulting from fertilization of the ovum. ... A sperm cell fertilizing an ovum This article is about reproduction in organisms. ... A spermatophore is a capsule or mass created by males of various invertebrate species, containing spermatozoa and transferred in entirety to the female during sex. ...

According to the classical hypothesis of Marr,^[5] derived from the results of the expedition of the famous British research vessel RRS Discovery, egg development then proceeds as follows: gastrulation (development of egg into embryo) sets in during the descent of the 0.6 mm eggs on the shelf at the bottom, in oceanic areas in depths around 2,000–3,000 m. From the time the egg hatches, the 1^st nauplius (i.e., larval stage) starts migrating towards the surface with the aid of its three pairs of legs; the so-called developmental ascent. The RRS Discovery was the last wooden three-masted ship to be built in the British Isles, and was launched on 21 March 1901, designed for Antarctic research. ... It has been suggested that epiboly be merged into this article or section. ... A millimetre (American spelling: millimeter, symbol mm) is an SI unit of length that is equal to one thousandth of a metre. ... The nauplius larva of a prawn A nauplius is the larva of many kinds of crustaceans. ...

The next two larval stages, termed 2^nd nauplius and metanauplius, still do not eat but are nourished by the remaining yolk. After three weeks, the little krill has finished the ascent. They can appear in enormous numbers counting 2 per liter in 60 m water depth. Growing larger, additional larval stages follow (2^nd and 3^rd calyptopis, 1^st to 6^th furcilia). They are characterized by increasing development of the additional legs, the compound eyes and the setae (bristles). At 15 mm, the juvenile krill resembles the habitus of the adults. Krill reach maturity after two to three years. Like all crustaceans, krill must molt in order to grow. Approximately every 13 to 20 days, krill shed their chitinous exoskeleton and leave it behind as exuvia.
The egg yolk is the yellow inside an egg. ... The litre or liter (see spelling differences) is a unit of volume. ... For the Dutch band, see Crustacean (band). ... Ecdysis is the molting of the cuticula in arthropods and related groups (Ecdysozoa). ... Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ... An exoskeleton is an external anatomical feature that supports and protects an animals body, in contrast to the internal endoskeleton of, for example, a human. ... Exuvia of an Antarctic krill. ...

Food

The head of Antarctic krill. Observe the bioluminescent organ at the eyestalk and the nerves visible in the antennae, the gastric mill, the filtering net at the thoracopods and the rakes at the tips of the thoracopods.

The gut of E. superba can often be seen shining green through the animal's transparent skin, an indication that this species feeds predominantly on phytoplankton—especially very small diatoms (20 μm), which it filters from the water with a feeding basket.^[6] The glass-like shells of the diatoms are cracked in the "gastric mill" and then digested in the hepatopancreas. The krill can also catch and eat copepods, amphipods and other small zooplankton. The gut forms a straight tube; its digestive efficiency is not very high and therefore a lot of carbon is still present in the feces (see "the biological pump" below). Download high resolution version (2006x1811, 253 KB)for higher resolution click on the image The head of Antarctic krill. ... Download high resolution version (2006x1811, 253 KB)for higher resolution click on the image The head of Antarctic krill. ... Bioluminescence is the production and emission of light by a living organism as the result of a chemical reaction during which chemical energy is converted to light energy. ... Nerves (yellow) Nerves redirects here. ... Insects display a wide variety of antennal shapes. ... Gastric mill is a part of the digestive tract of crustaceans. ... Thoracopod is the leg of crustacean used for walking, swimming feeding or filtration. ... Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of plankton. ... Orders Centrales Pennales Diatoms (Greek: (dia) = through + (temnein) = to cut, i. ... A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ... Orders Centrales Pennales Diatoms (Greek: (dia) = through + (temnein) = to cut, i. ... Gastric mill is a part of the digestive tract of crustaceans. ... Histology section of hepatopancreas of slug Deroceras laeve. ... Orders Calanoida Cyclopoida Gelyelloida Harpacticoida Misophrioida Monstrilloida Mormonilloida Platycopioida Poecilostomatoida Siphonostomatoida Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. ... Families about 200 partial list Alpheidae Ampeliscidae Amphilochidae Ampithoidae Anisogammaridae Aoridae Artesiidae Bogideillidae Bosminidae Caprellidae Corophiidae Crangonyctidae Eusiridae Gammaridae Hadziidae Haustoriidae Iphimediidae Ischyroceridae Leucothoidae Liljeborgiidae Lysianassidae Melitidae Phoxocephalidae Sebidae Talitridae Amphipoda (amphipods) include about 4600 different species of small, shrimp_like crustaceans. ... Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. ... For other uses, see Carbon (disambiguation). ... Horse feces Feces, faeces, or fæces (see spelling differences) is a waste product from an animals digestive tract expelled through the anus (or cloaca) during defecation. ...

In aquaria, krill have been observed to eat each other. When they are not fed in aquaria, they shrink in size after molting, which is exceptional for animals the size of krill. It is likely that this is an adaptation to the seasonality of their food supply, which is limited in the dark winter months under the ice.
“Aquaria” redirects here. ... Ecdysis is the molting of the cuticula in arthropods and related groups (Ecdysozoa). ... For other uses, see Adaptation (disambiguation). ...

Filter feeding

Krill feeding under high phytoplankton concentration. A slow motion video (from 300 frame/s; 490 kB) is also available.

Main article: Filter feeder

Antarctic krill manages to directly utilize the minute phytoplankton cells, which no other animal of krill size can do. This is accomplished through filter feeding, using the krill's highly developed front legs, providing for an efficient filtering apparatus:^[7] the six thoracopods (legs attached to the thorax) form a very effective "feeding basket" used to collect phytoplankton from the open water. In the finest areas the openings in this basket are only 1 μm in diameter. In the movie linked to the left, the krill is hovering at a 55° angle on the spot. In lower food concentrations, the feeding basket is pushed through the water for over half a meter in an opened position, as in the in situ image below, and then the algae are combed to the mouth opening with special setae (bristles) on the inner side of the thoracopods.
Still image of a filter-feeding Antarctic krill produced by Lupo from one frame of the animated GIF at Image:Filterkrillkils2. ... Still image of a filter-feeding Antarctic krill produced by Lupo from one frame of the animated GIF at Image:Filterkrillkils2. ... A section of Image:Filterkrillkils. ... Filter feeders (also known as suspension feeders) are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized structure, such as the baleen of baleen whales. ... Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of plankton. ... Filter feeders (also known as suspension feeders) are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized structure, such as the baleen of baleen whales. ... Thoracopod is the leg of crustacean used for walking, swimming feeding or filtration. ... Diagram of a tsetse fly, showing the head, thorax and abdomen The thorax is a division of an animals body that lies between the head and the abdomen. ... A seta is a stiff hair, bristle, or bristle-like process or part of an organism. ...

Ice-algae raking

Antarctic krill feeding off ice algae. The surface of the ice on the left side is colored green by the algae.

Antarctic krill can scrape off the green lawn of ice-algae from the underside of the pack ice.^[8][9] The image to the right, taken via a ROV,^[10] shows how most krill swim in an upside-down position directly under the ice. Only a single animal (in the middle) can be seen hovering in the free water. Krill have developed special rows of rake-like setae at the tips of the thoracopods, and graze the ice in a zig-zag fashion, akin to a lawnmower. One krill can clear an area of a square foot in about 10 minutes (1.5 cm²/s). It is relatively new knowledge that the film of ice algae is very well developed over vast areas, often containing much more carbon than the whole water column below. Krill find an extensive energy source here, especially in the spring.
krill scraping icealgae in antarctica - Photo Uwe Kils and Peter Marschall GFDL higher resolution and links http://www. ... krill scraping icealgae in antarctica - Photo Uwe Kils and Peter Marschall GFDL higher resolution and links http://www. ... Ice-algae is a general term used to describe all the various types of algal communities encountered in annual and multi-year sea-ice. ... Ice-algae is a general term used to describe all the various types of algal communities encountered in annual and multi-year sea-ice. ... An icebreaker navigates some through young (1 year) sea ice Sea ice is formed from ocean water that freezes. ... Remotely operated vehicles (ROV) are mobile tools used in environments too dangerous for humans. ... Levitation is the process by which an object is suspended against gravity, in a stable position, by a force without physical contact. ... Thoracopod is the leg of crustacean used for walking, swimming feeding or filtration. ...

The biological pump and carbon sequestration

In situ image taken with an ecoSCOPE. A green spit ball is visible in the lower right of the image and a green fecal string in the lower left.

The krill is a highly untidy feeder, and it often spits out aggregates of phytoplankton (spit balls) containing thousands of cells sticking together. It also produces fecal strings that still contain significant amounts of carbon and the glass shells of the diatoms. Both are heavy and sink very fast into the abyss. This process is called the biological pump. As the waters around Antarctica are very deep (2,000–4,000 m), they act as a carbon dioxide sink: this process exports large quantities of carbon (fixed carbon dioxide, CO₂) from the biosphere and sequesters it for about 1,000 years. in situ image spit ball and fecal string of Antarctic krill image Uwe Kils. ... in situ image spit ball and fecal string of Antarctic krill image Uwe Kils. ... This article needs cleanup. ... Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of plankton. ... For other uses, see Carbon (disambiguation). ... This article is about the material. ... Orders Centrales Pennales Diatoms (Greek: (dia) = through + (temnein) = to cut, i. ... In oceanic biogeochemistry, the biological pump is the sum of a suite of biologically-mediated processes that transport carbon from the surface euphotic zone to the oceans interior. ... It has been suggested that this article or section be merged with Carbon capture and storage. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Carbon sequestration from a fossil-fuel power station A carbon dioxide sink or CO2 sink is a carbon reservoir that is increasing in size, and is the opposite of a carbon source. The main sinks are the oceans and growing vegetation. ...

If the phytoplankton is consumed by other components of the pelagic ecosystem, most of the carbon remains in the upper strata. There is speculation that this process is one of the largest biofeedback mechanisms of the planet, maybe the most sizable of all, driven by a gigantic biomass. Still more research is needed to quantify the Southern Ocean ecosystem.

Biological peculiarities

Bioluminescence

Watercolor of bioluminescent krill

Krill are often referred to as light-shrimp because they can emit light, produced by bioluminescent organs. These organs are located on various parts of the individual krill's body: one pair of organs at the eyestalk (cf. the image of the head above), another pair on the hips of the 2^nd and 7^th thoracopods, and singular organs on the four pleonsternites. These light organs emit a yellow-green light periodically, for up to 2 to 3 seconds. They are considered so highly developed that they can be compared with a torchlight: a concave reflector in the back of the organ and a lens in the front guide the light produced, and the whole organ can be rotated by muscles. The function of these lights is not yet fully understood; some hypotheses have suggested they serve to compensate the krill's shadow so that they are not visible to predators from below; other speculations maintain that they play a significant role in mating or schooling at night. bioluminescence antarctic krill - watercolor by Uwe Kils GFDL more images and information: http://www. ... bioluminescence antarctic krill - watercolor by Uwe Kils GFDL more images and information: http://www. ... Bioluminescence is the production and emission of light by a living organism as the result of a chemical reaction during which chemical energy is converted to light energy. ... Thoracopod is the leg of crustacean used for walking, swimming feeding or filtration. ... Pleonsternite is a part of crustacean morphology Categories: Biology stubs ... IT FEELS REALLY GOOD IF YOU IMATATE THE ANIMALS. LOL! “Mounting” redirects here. ... This article is about swarms in biology. ...

Krill anre tiny and eaten by penguins The krill's bioluminescent organs contain several fluorescent substances. The major component has a maximum fluorescence at an excitation of 355 nm and emission of 510 nm.^[11]
Fluorescence induced by exposure to ultraviolet light in vials containing various sized Cadmium selenide (CdSe) quantum dots. ... A nanometre (American spelling: nanometer, symbol nm) is a unit of length in the metric system, equal to one thousand-millionth of a metre, which is the current SI base unit of length. ...

Escape reaction

Lobstering krill

Krill use an escape reaction to evade predators, swimming backwards very quickly by flipping their telson. This swimming pattern is also known as lobstering. Krill can reach speeds of over 60 cm/s.^[12] The trigger time to optical stimulus is, despite the low temperatures, only 55 ms.
krill escape flight - animation by Uwe Kils GFDL more links on http://www. ... krill escape flight - animation by Uwe Kils GFDL more links on http://www. ... Escape reaction (startle reaction) is a term used in behavior physiology to describe the details of the flight of attacked animals (predator/prey relationship). ... This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ... The telson is the last division of the body of a crustacean. ... Animated representation of lobstering. ... Induction IS retarded This page is a candidate for speedy deletion. ... In physiology, a stimulus is a detectable change in the internal or external environment. ... One millisecond is one-thousandth of a second. ...

The compound eye

Electron microscope image of the compound eye — the eyes are deep black in the living animal

Although the uses for and reasons behind the development of their massive black compound eyes remain a mystery, there is no doubt that Antarctic krill have one of the most fantastic structures for vision seen in nature^{[citation needed]}. Download high resolution version (1574x1505, 252 KB)Antarctic krill Euphausia superba (Photo by Gerd Alberti and Uwe Kils) GFDL goto large resolution File links The following pages link to this file: Scanning electron microscope Antarctic krill User talk:Jimbo Wales Eye Compound eye Image:Krilleyekils. ... Download high resolution version (1574x1505, 252 KB)Antarctic krill Euphausia superba (Photo by Gerd Alberti and Uwe Kils) GFDL goto large resolution File links The following pages link to this file: Scanning electron microscope Antarctic krill User talk:Jimbo Wales Eye Compound eye Image:Krilleyekils. ... An electron microscope is a type of microscope that uses electrons to illuminate and create an image of a specimen. ... Compound eye of a dragonfly Compound eye of Antarctic krill as imaged by an electron microscope A compound eye is a visual organ found in certain arthropods such as insects and crustaceans. ... In psychology, visual perception is the ability to interpret visible light information reaching the eyes which is then made available for planning and action. ...

As mentioned above, krill can shrink in size from one molt to the next, which is generally thought to be a survival strategy to adapt to scarce food supplies (a smaller body needs less energy, i.e., food). However, the animal's eyes do not shrink when this happens. The ratio between eye size and body length has thus been found to be a reliable indicator of starvation.^[13]

Geographical distribution

Krill distribution on a NASA SeaWIFS image — the main concentrations are in the Scotia Sea at the Antarctic Peninsula

Antarctic krill are found thronging the surface waters of the Southern Ocean; they have a circumpolar distribution, with the highest concentrations located in the Atlantic sector. distribution of krill on NASA image composed by uwe kils GFDL File links The following pages link to this file: Antarctic krill User:Kils/Antarctic krill User:Kils/Antarctic krill/frozen Virtual University/Antarctic krill ... distribution of krill on NASA image composed by uwe kils GFDL File links The following pages link to this file: Antarctic krill User:Kils/Antarctic krill User:Kils/Antarctic krill/frozen Virtual University/Antarctic krill ... This article is about the American space agency. ... SeaWiFS stands for Sea-viewing Wide Field-of-view Sensor. ... The Scotia Sea ( 57°30′ S 040°00′ W) is the portion of the Southern Ocean between Tierra Del Fuego, the Antarctic Peninsula, and South Georgia. ... Antarctic Peninsula map Booth Island and Mount Scott flank the narrow Lemaire Channel on the west side of the Antarctic Peninsula. ... “Atlantic” redirects here. ...

The northern boundary of the Southern Ocean with its Atlantic, Pacific Ocean and Indian Ocean sectors is defined more or less by the Antarctic convergence, a circumpolar front where the cold Antarctic surface water submerges below the warmer subantarctic waters. This front runs roughly at 55° South; from there to the continent, the Southern Ocean covers 32 million square kilometers. This is 65 times the size of the North Sea. In the winter season, more than three quarters of this area become covered by ice, whereas 24 million square kilometers become ice free in summer. The water temperatures range between −1.3 and 3°C. The subantarctic is a region in the Southern Hemisphere immediately north of the true Antarctic. ... Square kilometre (US spelling: Square kilometer), symbol km², is an SI unit of surface area. ... The North Sea is a sea of the Atlantic Ocean, located between the coasts of Norway and Denmark in the east, the coast of the British Isles in the west, and the German, Dutch, Belgian and French coasts in the south. ... Winter is one of the four seasons of temperate zones. ... For other uses, see Summer (disambiguation). ... Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ...

The waters of the Southern Ocean form a system of currents. Whenever there is a West Wind Drift, the surface strata travels around Antarctica in an easterly direction. Near the continent, the East Wind Drift runs counterclockwise. At the front between both, large eddies develop, for example, in the Weddell Sea. The krill schools drift with these water masses, to establish one single stock all around Antarctica, with gene exchange over the whole area. Currently, there is little knowledge of the precise migration patterns since individual krill cannot yet be tagged to track their movements.
The Antarctic Circumpolar Current (ACC) is an ocean current that flows from west to east around Antarctica. ... In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid flows past an obstacle. ... The Weddell Sea is part of the Southern Ocean. ...

Position in the Antarctic ecosystem

Antarctic krill is the keystone species of the Antarctica ecosystem, and provides an important food source for whales, seals, Leopard Seals, fur seals, Crabeater Seals, squid, icefish, penguins, albatrosses and many other species of birds. Crabeater seals have even developed special teeth as an adaptation to catch this abundant food source: its most unusual multilobed teeth enable this species to sieve krill from the water. Its dentition looks like a perfect strainer, but how it operates in detail is still unknown. Crabeaters are the most abundant seal in the world; 98% of their diet is made up of E. superba. These seals consume over 63 million tonnes of krill each year.^[14] Leopard seals have developed similar teeth (45% krill in diet). All seals consume 63–130 million tonnes, all whales 34–43 million tonnes, birds 15–20 million tonnes, squid 30–100 million tonnes, and fish 10–20 million tonnes, adding up to 152–313 million tonnes of krill consumption each year.^[15] This article is about the animal. ... subfamilies Otariidae Phocidae Odobenidae Pinnipeds are large marine mammals belonging to the Pinnipedia, a family (sometimes a suborder or superfamily, depending on the classification scheme) of the order Carnivora. ... Binomial name (Blainville, 1820) Hydrurga leptonyx range map. ... Genera Callorhinus Arctocephalus Fur seals, or Arctocephalinae make up one of the two distinct groups of marine mammals called seals. Fur seals are usually smaller than sea lions and have a coat of dense fur intermixed with guard hairs. ... Binomial name Hombron & Jacquinot, 1842 Distribution of Crabeater Seal The Crabeater Seal, Lobodon carcinophagus, is one of the most remarkable, though least known, of the mammals of the world. ... For other uses, see Squid (disambiguation). ... Species Chaenocephalus aceratus (16 more) The icefishes (or white-blooded fishes) are a family (Channichthyidae) of perciform fish found in the cold waters around Antarctica and southern South America. ... Modern genera Aptenodytes Eudyptes Eudyptula Megadyptes Pygoscelis Spheniscus For prehistoric genera, see Systematics Some penguins are curious. ... Genera Diomedea Thalassarche Phoebastria Phoebetria Albatrosses, of the biological family Diomedeidae, are large seabirds allied to the procellariids, storm-petrels and diving-petrels in the order Procellariiformes (the tubenoses). ... For other uses, see Bird (disambiguation). ... Binomial name Hombron & Jacquinot, 1842 Distribution of Crabeater Seal The Crabeater Seal, Lobodon carcinophagus, is one of the most remarkable, though least known, of the mammals of the world. ... A tonne or metric ton (symbol t), sometimes referred to as a metric tonne, is a measurement of mass equal to 1,000 kilograms. ... Binomial name (Blainville, 1820) Hydrurga leptonyx range map. ...

The size step between krill and its prey is unusually large: generally it takes three or four steps from the 20 μm small phytoplankton cells to a krill-sized organism (via small copepods, large copepods, mysids to 5 cm fish).^[2] The next size step in the food chain to the whales is also enormous, a phenomenon only found in the Antarctic ecosystem. E. superba lives only in the Southern Ocean. In the North Atlantic, Meganyctiphanes norvegica and in the Pacific, Euphausia pacifica are the dominant species. Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of plankton. ... Orders Calanoida Cyclopoida Gelyelloida Harpacticoida Misophrioida Monstrilloida Mormonilloida Platycopioida Poecilostomatoida Siphonostomatoida Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. ... Any of various small, shrimplike, chiefly marine crustaceans of the order Mysidacea, the females of which carry their eggs in a pouch beneath the thorax. ... For other uses, see Fish (disambiguation). ... This article does not cite any references or sources. ... This article is about the animal. ... For other uses, see Phenomena (disambiguation). ... The Antarctic ecosystem is one of the largest in the world. ... Binomial name Meganyctiphanes norvegica Northern Krill (Meganyctiphanes norvegica) is a crustacean that lives in the North Atlantic Ocean. ... Euphausia pacifica is small zooplankton organism in the Pacific. ...

Biomass and production

The biomass of Antarctic krill is estimated to be between 125 to 725 million tonnes,^[16] making E. superba the most successful animal species on the planet. It should be noted that of all animals visible to the naked eye some biologists speculate that ants provide the largest biomass (but this speculation adds up hundreds of different species) whilst others speculate that it could be the copepods, but this too would be the sum of many hundreds of species that exist over the planet. To get an impression of the biomass of E. superba against that of other species: The total non-krill yield from all world fisheries, finfish, shellfish, cephalopods and plankton is about 100 million tonnes per year whilst estimates of the Antarctic krill production are between 13 million to several billion tonnes per year. (Redirected from 1 E11 kg) Categories: Orders of magnitude (mass) ... A tonne or metric ton (symbol t), sometimes referred to as a metric tonne, is a measurement of mass equal to 1,000 kilograms. ... This article is about Earth as a planet. ... For other uses, see Ant (disambiguation). ... Orders Calanoida Cyclopoida Gelyelloida Harpacticoida Misophrioida Monstrilloida Mormonilloida Platycopioida Poecilostomatoida Siphonostomatoida Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. ... Cooked mussels Shellfish is a term used to describe shelled molluscs and crustaceans used as food. ... Orders Subclass Nautiloidea †Plectronocerida †Ellesmerocerida †Actinocerida †Pseudorthocerida †Endocerida †Tarphycerida †Oncocerida †Discosorida Nautilida †Orthocerida †Ascocerida †Bactritida Subclass †Ammonoidea †Goniatitida †Ceratitida †Ammonitida Subclass Coleoidea †Belemnoidea †Aulacocerida †Belemnitida †Hematitida †Phragmoteuthida Neocoleoidea (most living cephalopods) ?†Boletzkyida Sepiida Sepiolida Spirulida Teuthida Octopoda Vampyromorphida The cephalopods (Greek plural (kephalópoda); head-foot) are the mollusk class...

The reason Antarctic krill are able to build up such a high biomass and production is that the waters around the icy Antarctic continent harbor one of the largest plankton assemblages in the world, possibly the largest. The ocean is filled with phytoplankton; as the water rises from the depths to the light-flooded surface, it brings nutrients from all of the world's oceans back into the photic zone where they are once again available to living organisms. Photomontage of plankton organisms Plankton are any drifting organism that inhabits the water column of oceans, seas, and bodies of fresh water. ... Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of plankton. ... A nutrient is either a chemical element or compound used in an organisms metabolism or physiology. ... The photic zone is the depth of the water, whether in a lake or an ocean, that is exposed to sufficient sunlight for photosynthesis to occur. ...

Thus primary production — the conversion of sunlight into organic biomass, the foundation of the food chain — has an annual carbon fixation of between 1 and 2 g/m² in the open ocean. Close to the ice it can reach 30–50 g/m². These values are not outstandingly high, compared to very productive areas like the North Sea or upwelling regions, but the area over which it takes place is just enormous, even compared to other large primary producers such as rainforests. In addition, during the Austral summer there are many hours of daylight to fuel the process. All of these factors make the plankton and the krill a critical part of the planet's ecocycle.
Global oceanic and terrestrial photoautotroph abundance, from September 1997 to August 2000. ... The North Sea is a sea of the Atlantic Ocean, located between the coasts of Norway and Denmark in the east, the coast of the British Isles in the west, and the German, Dutch, Belgian and French coasts in the south. ... Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water. ... The Daintree Rainforest in Queensland, Australia. ...

Decline with shrinking pack ice

after data compiled by Loeb et al. 1997^[17] — temperature and pack ice area — the scale for the ice is inverted to demonstrate the correlation — the horizontal line is the freezing point — the oblique line the average of the temperature — in 1995 the temperature reached the freezing point

There are concerns that the overall biomass of Antarctic krill has been declining rapidly over the last few decades. Some scientists have speculated this value being as high as 80%. This could be caused by the reduction of the pack ice zone due to global warming.^[18] The graph on the right depicts the rising temperatures of the Southern Ocean and the loss of pack ice (on an inverted scale) over the last years 40 years. Antarctic krill, especially in the early stages of development, seem to need the pack ice structures in order to have a fair chance of survival. The pack ice provides natural cave-like features which the krill uses to evade their predators. In the years of low pack ice conditions the krill tend to give way to salps,^[19] a barrel-shaped free-floating filter feeder that also grazes on plankton. ice reduction southern ocean graph uwe kils after data from Loeb V, Siegel V, Holm-Hansen O, Hewitt R, Fraser W, et al. ... ice reduction southern ocean graph uwe kils after data from Loeb V, Siegel V, Holm-Hansen O, Hewitt R, Fraser W, et al. ... An icebreaker navigates some through young (1 year) sea ice Sea ice is formed from ocean water that freezes. ... Global warming refers to the increase in the average temperature of the Earths near-surface air and oceans in recent decades and its projected continuation. ... A salp is a barrel-shaped, free-floating tunicate that moves by pumping water through its gelatinous bodies by means of contraction, and strains the water, feeding on phytoplankton. ... Filter feeders (also known as suspension feeders) are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized structure, such as the baleen of baleen whales. ...

Fisheries

Annual world catch of E. superba, compiled from FAO data.^[16]

Main article: Krill fishery

The fishery of Antarctic krill is on the order of 100,000 tonnes per year. The major catching nations are Japan and Poland. The products are used largely in Japan as a delicacy and worldwide as animal food and fish bait. Krill fisheries are difficult to operate in two important respects. First, a krill net needs to have very fine meshes, producing a very high drag, which generates a bow wave that deflects the krill to the sides. Second, fine meshes tend to clog very fast. Additionally, fine nets also tend to be very delicate, and the first krill nets tore apart while fishing through krill schools. catch of krill from FAO data composed by uwe kils GFDL File links The following pages link to this file: Antarctic krill User:Kils/Antarctic krill User:Kils/Antarctic krill/frozen Virtual University/Antarctic krill ... catch of krill from FAO data composed by uwe kils GFDL File links The following pages link to this file: Antarctic krill User:Kils/Antarctic krill User:Kils/Antarctic krill/frozen Virtual University/Antarctic krill ... The Food and Agriculture Organization of the United Nations (FAO) is a specialized agency of the United Nations that leads international efforts to defeat hunger. ... Krill fishery is the commercial fishery of krill, small shrimp-like marine animals that live in the oceans world-wide. ... This is a List of delicacies. ... An object falling through a gas or liquid experiences a force in direction opposite to its motion. ... A bow wave is the wave that forms at the bow of a boat when it moves through the water. ...

Yet another problem is bringing the krill catch on board. When the full net is hauled out of the water, the organisms compress each other, resulting in great loss of the krill's liquids. Experiments have been carried out to pump krill, while still in water, through a large tube on board. Special krill nets also are currently under development. The processing of the krill must be very rapid since the catch deteriorates within several hours. Processing aims are splitting the muscular hind part from the front part and separating the chitin armor, in order to produce frosted products and concentrate powders. Its high protein and vitamin content makes krill quite suitable for both direct human consumption and the animal-feed industry.^[20]
Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ...

Future visions and ocean engineering

Despite the lack of knowledge available about the whole Antarctic ecosystem, large scale experiments involving krill are already being performed to increase carbon sequestration: in vast areas of the Southern Ocean there are plenty of nutrients, but still, the phytoplankton does not grow much. These areas are termed HNLC (high nutrient, low carbon). The phenomenon is called the Antarctic Paradox, and occurs because iron is missing.^[21] Relatively small injections of iron from research vessels trigger very large blooms, covering many miles. The hope is that such large scale exercises will draw down carbon dioxide as compensation for the burning of fossil fuels.^[22] Krill is the key player in this process, collecting the minute plankton cells which fix carbon dioxide and converting the substance to rapidly-sinking carbon in the form of spit balls and fecal strings. The vision is that in the future a fleet of tankers would circle the Southern Seas, injecting iron, so this relatively unknown animal might help keep cars and air conditioners running.
Carbon sequestration from a fossil-fuel power station A carbon dioxide sink or CO2 sink is a carbon reservoir that is increasing in size, and is the opposite of a carbon source. The main sinks are the oceans and growing vegetation. ... HNLC stands for high nitrate, low carbon - a term used in marine ecology to describe areas in the ocean where the phytoplankton development is low in spite of high nutrient contents, caused by the lack of iron. ... Antarctic Paradox is a term in ecology that describes the phenomenon that in vast areas of the Southern Ocean there are plenty of nutrients for phytoplankton to thrive but still, the phytoplankton do not grow much. ... For other uses, see Iron (disambiguation). ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Fossil fuels are hydrocarbons, primarily coal and petroleum (fuel oil or natural gas), formed from the fossilized remains of dead plants and animals[1] by exposure to heat and pressure in the Earths crust over hundreds of millions of years[2]. The theory that hydrocarbons were formed from these...

Notes

References

Science is the journal of the American Association for the Advancement of Science (AAAS). ... The Food and Agriculture Organization of the United Nations (FAO) is a specialized agency of the United Nations that leads international efforts to defeat hunger. ... The Alfred Wegener Institute of Polar and Marine Research is a scientific organization located in Bremerhaven, Germany. ... Pergamon Press was a United Kingdom based publishing house, founded by Robert Maxwell, which published general science books. ... The Food and Agriculture Organization of the United Nations (FAO) is a specialized agency of the United Nations that leads international efforts to defeat hunger. ... Nature is a prominent scientific journal, first published on 4 November 1869. ... Nature is a prominent scientific journal, first published on 4 November 1869. ...

Further reading

Wikispecies has information related to:

Euphausia superba

Image File history File links Wikispecies-logo. ... Wikispecies is a wiki-based online project supported by the Wikimedia Foundation that aims to create a comprehensive free content catalogue of all species (including animalia, plantae, fungi, bacteria, archaea, and protista). ...

External links

Wikimedia Commons has media related to:

Euphausia superba

Listen to this article ( info/dl)

This audio file was created from an article revision dated 2005-09-03, and may not reflect subsequent edits to the article. (Audio help)

More spoken articles

   

• Euphausia superba from MarineBio.
• "Virtual microscope" of Antarctic krill for an interactive tour of their morphology and behavior, along with other peer-reviewed information.
• "Krill fights for survival as sea ice melts" from the NASA's "Earth Observatory".
• "Antarctic Wildlife at Risk From Overfishing, Experts Say", from National Geographic News, August 5, 2003.
• Diary of the RRS James Clark Ross, giving a popular introduction to the Antarctic krill.
• "Climate row touches blue whales", from the BBC, July 19, 2001.
• A time to krill
• Extensive bibliography.
• Krill Count Project
• WIKIversity Lecture "Biology of Antarctica"

Image File history File links Commons-logo. ... Image File history File links Antarctic_krill. ... Image File history File links Sound-icon. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... is the 246th day of the year (247th in leap years) in the Gregorian calendar. ... Image File history File links Sound-icon. ... This article is about the American space agency. ... The National Geographic Society was founded in the USA on January 27, 1888, by 33 men interested in organizing a society for the increase and diffusion of geographical knowledge. ... is the 217th day of the year (218th in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... RRS may stand for: Racing Rules of Sailing Royal Research Ship This page concerning a three-letter acronym or abbreviation is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... For other uses, see BBC (disambiguation). ... is the 200th day of the year (201st in leap years) in the Gregorian calendar. ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ...