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| {{Taxobox_end}} | {{Taxobox_end}} | ||
| '''Antarctic krill''' (''Euphausia superba''{{ref|spelling}}) is a species of ] found in ] waters |
The '''Antarctic krill''' (''Euphausia superba'' {{ref|spelling}}) is a ] of ] found in the ] waters of the ]. | ||
| Krill live in large |
Krill live in large, dense schools called ]s, or ], with up to 20,000 individual krill per cubic meter. An important factor in ], krill feed on ], converting the ] in order to sustain their ] ] . They grow to a length of 6 cm, weigh upto 2 ]s, and can live up to six years. | ||
| ==Geographical Distribution== | ==Geographical Distribution== | ||
| ⚫ | Krill are found thronging the surface waters of the ]; they have a circumpolar distribution, with the highest concentrations located in the ] sector. This Antarctic convergence defines more or less the northern boundary of the Southern Ocean. That is, the circumpolar front where the cold Antarctic surface water submerges below the warmer ] waters. | ||
| ⚫ | ] ] image]] | ||
| ⚫ | Krill |
||
| The Southern Ocean with its Atlantic, Pacific and Indian sectors stretches from the polarfront at ca. 55 degree South to the edge of the continent, covering 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 |
The Southern Ocean, with its Atlantic, ] and ] sectors, stretches from the polarfront at ca. 55 degree South to the edge of the continent, covering 32 million square kilometers. This is 65 times the size of the ]. In the ] season, more than three quarters of this area become covered by ice – compared to the 24 million square kilometers which become icefree in the ]. The water temperatures range between - 1.3 and 3 degree ]. | ||
| The waters of the Southern Ocean form a system of currents. |
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 ] develop, for example, in the ]. The krill schools drifts with these watermasses, to establish one single stock all around Antarctica, with gene exchange over the whole area. Currently, there is little knowledge of this migration patterns since it is not yet possible to place tags on krill for the purposes of tracking their movements. | ||
| <br style="clear:both"> <!-- force image to begin on new line --> | <br style="clear:both"> <!-- force image to begin on new line --> | ||
| ==Position in the Antarctic ecosystem== | ==Position in the Antarctic ecosystem== | ||
| ⚫ | ] ] image]] | ||
| Antarctic krill is the keystone species of the |
The Antarctic krill is the keystone species of the ] ecosystem , and provides an important food source for ]s, ], ]s, ]s, ]s, ], ], ]s, ]es and many other species of ]s. The size-step between krill and its prey is unusually large, normally taking three or four steps from the 20 ]-small ] for krill-sized organisms (via ]s and small ]){{ref|kils1}}. The next size-step in the ] of ]s, is also enormous, a ] only found in the ]. ''E. superba'' lives only in the Southern Ocean. In the North Atlantic, '']'' and in the Pacific, '']'' are the dominant species. | ||
| ==Systematic== | ==Systematic== | ||
| The order ] are shrimplike ]. All ]s are joined |
The order ] are shrimplike ]. All ]s are joined with the ]. The short length of the thoracomers on each side of the carapace, makes the gills of the Antartic krill visible to the human eye. The ]s do not form a ], which differentiates this order versus the ]. | ||
| ==Biomass== | ==Biomass== | ||
| The Antarctic Krill's biomass is estimated to be between ] ]s, making ''E. superba'' the most successful animal on the ]; for comparison, the total non-krill yield from all world fisheries is about 100 million tonnes per year. The reason krill are able to build up such a high biomass is due to the waters around the icy continent harbors exhibiting one of the the largest ] assemblages in ther world, possibly the largest. It is filled with ], as the water rises from the depths to the light flooded surface, bringing ]s from all the oceans back to the ]. | |||
| <br style="clear:both"> <!-- force image to begin on new line --> | <br style="clear:both"> <!-- force image to begin on new line --> | ||
| ==Decline with shrinking pack ice== | ==Decline with shrinking pack ice== | ||
| ] | ] | ||
| There are |
There are concerns that the Antarctic Krill's overall biomass 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 ] zone due to the consequence of ] (review in Gross 2005{{ref|gross}}). 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. Antartic Krill, especially in the early stages of development, seem to requiere the pack ice structures in order to have a fair chance of survival. The pack ice provides natural cave-like features, cave-like features which the Krill uses to evade their predators. In the years prior to the decline in the average amount of pack ice, the Krill's natural predators substituted it as a food source with ]s in order to feed. (Atkinson et. al., 2004{{ref|atkinson}}). | ||
| <br style="clear:both"> <!-- force image to begin on new line --> | <br style="clear:both"> <!-- force image to begin on new line --> | ||
| ==Fisheries== | ==Fisheries== | ||
| ] data]] | ] data]] | ||
| The fishery of Antarctic krill is on the order of 90,000 tonnes per year. The products are used in Japan |
The fishery of the Antarctic krill is on the order of 90,000 tonnes per year. The products are used largely in ] for feeds. Krill fisheries are difficult in two important respects: first, because a krill net needs to have very fine meshes as it has a very high drag, producing a bow wave, deflecting the krill to the sides. Second, fine meshes tend to clog very fast. Additionally, a fine net is also, by definition, a very delicate net, and the first krill nets designed literally exploded while fishing through the krill schools. Yet another problem is bringing the krill catch on board. | ||
| During hauling of the full net out of the water the organisms compress each other, |
During hauling of the full net out of the water, the organisms compress each other, resulting in great loss of the krill's moisture. Experiments have been carried out to pump krill, while still in water, through a large tube on board. As well, a special krill net is currently under development. | ||
| The processing of the krill |
The processing of the krill must be very rapid since the catch deteriorates within several hours. One aim, involves 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. | ||
| <br style="clear:both"> <!-- force image to begin on new line --> | <br style="clear:both"> <!-- force image to begin on new line --> | ||
| ==Food== | ==Food== | ||
| ] at the ] and the ]s visible in the ], the filtering net at the ]s and the rakes at the tips of the thoracopods.]] | ] at the ] and the ]s visible in the ], the filtering net at the ]s and the rakes at the tips of the thoracopods.]] | ||
| The gut of ''E. superba'' can often be seen shining in green through |
The gut of ''E. superba'' can often be seen to be shining in green, through it is a transparent skin, an indication that this species feeds predominantly on ] – especially very small ]s (20 micrometer), which it filters from the water with a "feeding basket" (see below), but they can also catch ]s, ]s and other small ]. In aquaria, they have been observed eating each other. When they are not fed in aquaria, they shrink in size after ], which, by nature, is exceptional for animals the size of krill. Likely this is an adaption for the seasonality of its food supply, which is mostly limited to the dark winter months under the ice. | ||
| <br style="clear:both"> <!-- force image to begin on new line --> | <br style="clear:both"> <!-- force image to begin on new line --> | ||
| ==Bioluminescence== | ==Bioluminescence== | ||
| ] | ] | ||
| Krill are often referred to as ''light-shrimp'' because they can emit light |
Krill are often referred to as ''light-shrimp'' because they can emit light. This is produced by light emitting organs – see: (]). These organs are located on various parts of the individual krill's body: one pair of organs at the ] (a high magnification image of the head can be accessed ), and another pair on the hips of the 2nd and 7th ]s and singlular organs are located on the four ]s. These lightorgans will emit a yellow-green light from time to time, for upto 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 lens in the front guide produce the light, and the whole organ is rotatable through muscles. The function of this light is not yet fully clear, 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 it plays a significant role in ] or ] at night. | ||
| <br style="clear:both"> <!-- force image to begin on new line --> | <br style="clear:both"> <!-- force image to begin on new line --> | ||
| ==Development== | ==Development== | ||
| ] | ] | ||
| The main spawning time of krill is from January |
The main spawning time of krill is from January through March, over the shelf, but also in oceanic areas over deep waters. As it is typical for euphausiaceans, the male attaches a sperm package to the genital opening of the female. For this purpose, the first pleopods of the male are constructed as tools. According to the classical hypothesis of MARR 1962{{ref|marr}}, which he derived from the results of the great Discovery-Expedition, the development is as follows: ] sets in during the descent of the 0.6 mm eggs on the shelf at the bottom, in oceanic areas in depths around 2000 m. From the time the egg hatches, the 1st ] starts the migration towards the surface with the aid of its three pairs of legs ("developmental ascent"). The next two larval stages, 2nd nauplius and metanauplius, do not eat but are nourished by the yolk. After three weeks, the little krill has finished the 1st calyptopis ascent. Growing larger, additional larval stages follow (2nd and 3rd calyptopis, 1st to 6th furcilia). They are characterized by increasing development of the additional legs, the compound eyes and the setae. At 15 mm, the juvenile krill resembles the habitus of the adults. After two to three years, krill reaches maturity. As characteristic of all crustaceans, krill must molt in order to grow. Approximately every 13 to 20 days krill ejects from its chitin skin and leaves it as exuvia behind. | ||
| <br style="clear:both"> <!-- force image to begin on new line --> | <br style="clear:both"> <!-- force image to begin on new line --> | ||
| ==]== | ==]== | ||
| ⚫ | The Antarctic krill manages to utilize directly the minute ] cells (which no other higher animal of krill size can do such). This is accomplished with the krill's developed front legs, providing for a very efficient filtering apparatus (Kils 1983{{ref|kils3}}): Slow motion movie (300 frames per second) of ] of the feeding basket, formed by the six ]s shown by krill collecting ] from the open water. The krill is hovering at a 55 degree angle at the spot. This process takes place under very high phytoplankton concentrations. In lower food concentrations, the feeding basket is pushed through the water for over half a meter in an opened position, like in the ''in situ'' image below, and then they comb the algae to the mouth opening with special setae on the inner side of the thoracopods. The fine structure of the feeding basket on ] images can be seen . | ||
| ] | |||
| ⚫ | |||
| <br style="clear:both"> <!-- force image to begin on new line --> | <br style="clear:both"> <!-- force image to begin on new line --> | ||
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| ] | ] | ||
| Krill can scrape off the green lawn of ] from the underside of the ] (Marschall 1988{{ref|marschall}}). |
Krill can scrape off the green lawn of ] from the underside of the ] (Marschall 1988{{ref|marschall}}). The image to the right, taken via a ] (image from Kils & Marschall 1995{{ref|kils4}}), features how most krill swim in an upside-down position directly under the ice. Only a single animal (in the middle) can be seen ]ing in the free water. Krill have developed special rows of rake, like setae at the tips of the ]s, and graze the ice in a zig-zak fashion, akin to a lawnmower. | ||
| <br style="clear:both"> | <br style="clear:both"> | ||
| ==]== | ==]== | ||
| ⚫ | Krill ]s ]s with the aid of very fast backward swimming (]), flipping its ]. They can reach speeds of over 60 cm per second (Kils 1982{{ref|kils2}}). The ] time to optical ] is, despite the low temperatures, only 55 milliseconds. | ||
| ] | |||
| ⚫ | Krill ]s ]s |
||
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| Line 88: | Line 85: | ||
| ==The Biological Pump and Carbon Sequestration== | ==The Biological Pump and Carbon Sequestration== | ||
| ] - a green ] is visible in the lower right of the image and a green ] in the lower middle (for higher resolution and history click into the image)]] | ] - a green ] is visible in the lower right of the image and a green ] in the lower middle (for higher resolution and history click into the image)]] | ||
| The krill is a highly untidy feeder, and it often spits out ]s of ] (]s) containing thousands of cells sticking together. Also it produces ]s, which still contain plenty of ] and the ] shells of the ]s. Both are heavy and sink very fast into the abyss. This process is called ]. As the waters around ] are very deep (2000 - 4000 m), this process exports large quantities of carbon (fixed ]) from the biosphere and sequesters it for about 1000 years (], ]). If the phytoplankton is consumed by other components of the pelagic ecosystem, most of the carbon retains in the upper strata. There are speculations that this process is one of the largest ]s of the planet, maybe the most sizable of them all, driven by a gigantic biomass. Still, plenty of additional research needs to be carried out for a in order to verify this claim. | |||
| <br style="clear:both"> <!-- force image to begin on new line --> | <br style="clear:both"> <!-- force image to begin on new line --> | ||
| ==Future visions and Ocean Engineering== | ==Future visions and Ocean Engineering== | ||
| Regardless of the diminished available knowledge, there are large scale experiments 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 coined ] (high nutrient, low carbon). The phenomenon is called ]. The reason is that ] is missing . Relatively small injections of iron from research vessels trigger very large blooms covering many miles. The hope is that such |
Regardless of the diminished available knowledge, there are large scale experiments 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 coined ] (high nutrient, low carbon). The phenomenon is called ]. The reason for this is that ] is missing . 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 ] as compensation for the burning of ]s . Krill is the key player in collecting the minute plankton cells so as to sink faster, in the form of spit balls and fecal strings. The general idea is that in the future a fleet of tankers would be able to circle the Southern Seas, injecting iron, so this relatively unknown animal might help keep cars and airconditioners running. | ||
| <br style="clear:both"> <!-- force image to begin on new line --> | <br style="clear:both"> <!-- force image to begin on new line --> | ||
Revision as of 02:47, 14 June 2005
Template:Taxobox begin Template:Taxobox image Template:Taxobox begin placement Template:Taxobox regnum entry Template:Taxobox phylum entry Template:Taxobox subphylum entry Template:Taxobox classis entry Template:Taxobox ordo entry Template:Taxobox familia entry Template:Taxobox genus entry Template:Taxobox species entry Template:Taxobox end placement Template:Taxobox section binomial Template:Taxobox end
The Antarctic krill (Euphausia superba ) is a species of krill found in the Antarctic waters of the Southern Ocean.
Krill live in large, dense schools called swarms, or clouds, with up to 20,000 individual krill per cubic meter. An important factor in primary production, krill feed on phytoplankton, converting the energy in order to sustain their pelagic life cycle . They grow to a length of 6 cm, weigh upto 2 grams, and can live up to six years.
Geographical Distribution
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. This Antarctic convergence defines more or less the northern boundary of the Southern Ocean. That is, the circumpolar front where the cold Antarctic surface water submerges below the warmer subantarctic waters.
The Southern Ocean, with its Atlantic, Pacific Ocean and Indian Ocean sectors, stretches from the polarfront at ca. 55 degree South to the edge of the continent, covering 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 – compared to the 24 million square kilometers which become icefree in the summer. The water temperatures range between - 1.3 and 3 degree Centigrade.
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 drifts with these watermasses, to establish one single stock all around Antarctica, with gene exchange over the whole area. Currently, there is little knowledge of this migration patterns since it is not yet possible to place tags on krill for the purposes of tracking their movements.
Position in the Antarctic ecosystem
The 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. The size-step between krill and its prey is unusually large, normally taking three or four steps from the 20 micrometer-small phytoplankton for krill-sized organisms (via copepods and small fish). The next size-step in the food chain of 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.
Systematic
The order euphausiacea are shrimplike eucarida. All thoracomers are joined with the carapace. The short length of the thoracomers on each side of the carapace, makes the gills of the Antartic krill visible to the human eye. The thoracopods do not form a gnathopod, which differentiates this order versus the decapoda. Wikispecies
Biomass
The Antarctic Krill's biomass is estimated to be between 100 and 800 million tonnes, making E. superba the most successful animal on the planet; for comparison, the total non-krill yield from all world fisheries is about 100 million tonnes per year. The reason krill are able to build up such a high biomass is due to the waters around the icy continent harbors exhibiting one of the the largest plankton assemblages in ther world, possibly the largest. It is filled with phytoplankton, as the water rises from the depths to the light flooded surface, bringing nutrients from all the oceans back to the photic zone.
Decline with shrinking pack ice
There are concerns that the Antarctic Krill's overall biomass 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 the consequence of global warming (review in Gross 2005). 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. Antartic Krill, especially in the early stages of development, seem to requiere the pack ice structures in order to have a fair chance of survival. The pack ice provides natural cave-like features, cave-like features which the Krill uses to evade their predators. In the years prior to the decline in the average amount of pack ice, the Krill's natural predators substituted it as a food source with Salps in order to feed. (Atkinson et. al., 2004).
Fisheries
The fishery of the Antarctic krill is on the order of 90,000 tonnes per year. The products are used largely in Japan for feeds. Krill fisheries are difficult in two important respects: first, because a krill net needs to have very fine meshes as it has a very high drag, producing a bow wave, deflecting the krill to the sides. Second, fine meshes tend to clog very fast. Additionally, a fine net is also, by definition, a very delicate net, and the first krill nets designed literally exploded while fishing through the krill schools. Yet another problem is bringing the krill catch on board.
During hauling of the full net out of the water, the organisms compress each other, resulting in great loss of the krill's moisture. Experiments have been carried out to pump krill, while still in water, through a large tube on board. As well, a special krill net is currently under development.
The processing of the krill must be very rapid since the catch deteriorates within several hours. One aim, involves 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.
Food
The gut of E. superba can often be seen to be shining in green, through it is a transparent skin, an indication that this species feeds predominantly on phytoplankton – especially very small diatoms (20 micrometer), which it filters from the water with a "feeding basket" (see below), but they can also catch copepods, amphipods and other small zooplankton. In aquaria, they have been observed eating each other. When they are not fed in aquaria, they shrink in size after molting, which, by nature, is exceptional for animals the size of krill. Likely this is an adaption for the seasonality of its food supply, which is mostly limited to the dark winter months under the ice.
Bioluminescence
Krill are often referred to as light-shrimp because they can emit light. This is produced by light emitting organs – see: (bioluminescence). These organs are located on various parts of the individual krill's body: one pair of organs at the eyestalk (a high magnification image of the head can be accessed here), and another pair on the hips of the 2nd and 7th thoracopods and singlular organs are located on the four pleonsternites. These lightorgans will emit a yellow-green light from time to time, for upto 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 lens in the front guide produce the light, and the whole organ is rotatable through muscles. The function of this light is not yet fully clear, 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 it plays a significant role in mating or schooling at night.
Development
The main spawning time of krill is from January through March, over the shelf, but also in oceanic areas over deep waters. As it is typical for euphausiaceans, the male attaches a sperm package to the genital opening of the female. For this purpose, the first pleopods of the male are constructed as tools. According to the classical hypothesis of MARR 1962, which he derived from the results of the great Discovery-Expedition, the development is as follows: Gastrulation sets in during the descent of the 0.6 mm eggs on the shelf at the bottom, in oceanic areas in depths around 2000 m. From the time the egg hatches, the 1st nauplius starts the migration towards the surface with the aid of its three pairs of legs ("developmental ascent"). The next two larval stages, 2nd nauplius and metanauplius, do not eat but are nourished by the yolk. After three weeks, the little krill has finished the 1st calyptopis ascent. Growing larger, additional larval stages follow (2nd and 3rd calyptopis, 1st to 6th furcilia). They are characterized by increasing development of the additional legs, the compound eyes and the setae. At 15 mm, the juvenile krill resembles the habitus of the adults. After two to three years, krill reaches maturity. As characteristic of all crustaceans, krill must molt in order to grow. Approximately every 13 to 20 days krill ejects from its chitin skin and leaves it as exuvia behind.
Filter feeding
The Antarctic krill manages to utilize directly the minute phytoplankton cells (which no other higher animal of krill size can do such). This is accomplished with the krill's developed front legs, providing for a very efficient filtering apparatus (Kils 1983): Slow motion movie (300 frames per second) of pump filtering of the feeding basket, formed by the six thoracopods shown by krill collecting phytoplankton from the open water. The krill is hovering at a 55 degree angle at the spot. This process takes place under very high phytoplankton concentrations. In lower food concentrations, the feeding basket is pushed through the water for over half a meter in an opened position, like in the in situ image below, and then they comb the algae to the mouth opening with special setae on the inner side of the thoracopods. The fine structure of the feeding basket on electron microscope images can be seen here.
Ice-algae raking
Krill can scrape off the green lawn of ice-algae from the underside of the pack ice (Marschall 1988). The image to the right, taken via a ROV (image from Kils & Marschall 1995), features 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-zak fashion, akin to a lawnmower.
Escape reaction
Krill evades predators with the aid of very fast backward swimming (lobstering), flipping its telson. They can reach speeds of over 60 cm per second (Kils 1982). The trigger time to optical stimulus is, despite the low temperatures, only 55 milliseconds.
The compound eye
Although the uses 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.
The Biological Pump and Carbon Sequestration
The krill is a highly untidy feeder, and it often spits out aggregates of phytoplankton (spit balls) containing thousands of cells sticking together. Also it produces fecal strings, which still contain plenty of carbon and the glass shells of the diatoms. Both are heavy and sink very fast into the abyss. This process is called Biological pump. As the waters around Antarctica are very deep (2000 - 4000 m), this process exports large quantities of carbon (fixed ]) from the biosphere and sequesters it for about 1000 years (Carbon Sequestration, Carbon dioxide sink). If the phytoplankton is consumed by other components of the pelagic ecosystem, most of the carbon retains in the upper strata. There are speculations that this process is one of the largest bio-feedbacks of the planet, maybe the most sizable of them all, driven by a gigantic biomass. Still, plenty of additional research needs to be carried out for a in order to verify this claim.
Future visions and Ocean Engineering
Regardless of the diminished available knowledge, there are large scale experiments 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 coined HNLC (high nutrient, low carbon). The phenomenon is called Antarctic Paradoxon. The reason for this is that iron is missing . 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 . Krill is the key player in collecting the minute plankton cells so as to sink faster, in the form of spit balls and fecal strings. The general idea is that in the future a fleet of tankers would be able to circle the Southern Seas, injecting iron, so this relatively unknown animal might help keep cars and airconditioners running.
References
Atkinson A, Siegel V, Pakhomov E, Rothery P 2004 Long-term decline in krill stock and increase in salps within the Southern Ocean. Nature 432:100-103
Gross L 2005 As the Antarctic Ice Pack Recedes, a Fragile Ecosystem Hangs in the Balance. PLoS Biol 3(4):127
Kils U & Klages N 1979 Der Krill. Naturwissenschaftliche Rundschau 10:397-402 (English translation: The Krill)
Kils U 1982 Swimming behavior, Swimming Performance and Energy Balance of Antarctic Krill Euphausia superba. BIOMASS Scientific Series 3, BIOMASS Research Series, 1-122
Kils U 1983 Swimming and feeding of Antarctic Krill, Euphausia superba - some outstanding energetics and dynamics - some unique morphological details. In: Berichte zur Polarforschung, Alfred Wegener Institut fuer Polarforschung, Sonderheft 4 (1983) On the biology of Krill Euphausia superba, Proceedings of the Seminar and Report of Krill Ecology Group, Editor S. B. Schnack, 130-155 and title page image
Kils U & Marschall P 1995 Der Krill, wie er schwimmt und frisst - neue Einsichten mit neuen Methoden (The antarctic krill - feeding and swimming performances - new insights with new methods) In Hempel I, Hempel G, Biologie der Polarmeere - Erlebnisse und Ergebnisse (Biology of the polar oceans) Fischer Jena - Stuttgart - New York, 201-207 (and images p 209-210)
Loeb V, Siegel V, Holm-Hansen O, Hewitt R, Fraser W, et al. 1997 Effects of sea-ice extent and krill or salp dominance on the Antarctic food web. Nature 387:897-900
Marr J W S 1962 The natural history and geography of the Antarctic Krill Euphausia superba - Discovery report 32:33-464
Marschall P 1988 The overwintering strategy of Antarctic krill under the pack ice of the Weddell Sea - Polar Biol 9:129-135
External links
- "Virtual microscope" of Antarctic krill for interactive dives into their morphology and behavior, along with other peer-reviewed information
- high resolution images on Wikisource
Notes
This species is often misspelled Euphasia superba or Eupausia superba .
Category: