#redirect Antarctic krill
#redirect Talk:Antarctic krill
The Antarctic krill (''Euphausia superba'' ) is a species of krill found in the Antarctica waters of the Southern Ocean. Antarctic krill (shrimp-like invertebrates) live in large schools, called swarms, sometimes reaching densities of 10,000–30,000 individual animals per cubic meter. They feed directly on minute phytoplankton, thereby using the primary production energy originally derived from the sun in order to sustain their pelagic life cycle. They grow to a length of 6 cm, weigh up to 2 grams, and can live for up to six years. They are the key species in the Antarctic ecosystem and are probably, in terms of biomass, the most successful animal species on the planet (~500 million tonnes). ==Systematics== All members of the euphausiacea 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 the Antartic krill visible to the human eye. The thoracopod do not form a gnathopod, which differentiates this order from the decapoda. (''See also [http://species.wikipedia.org/wiki/Euphausia_superba ''Euphausia superba'' at Wikispecies].'') ==Life history== The main spawning time of Antarctic krill is from January through 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 of the male are constructed as tools. Females lay 6,000–10,000 eggs at one time. They are fertilised as they pass out of the genital opening by sperm liberated from spermatophores which have been attached by the males. According to the classical hypothesis of Marr, derived from the results of the expedition of the famous British research vessel "Discovery", egg development then proceeds 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 2,000–3,000 m. From the time the egg hatches, the 1st Nauplius_(larva) (i.e., larval stage) starts migrating towards the surface with the aid of its three pairs of legs; the so-called ''developmental ascent''. The next two larval stages, termed 2nd nauplius and metanauplius, still do not eat but are nourished by the remaining yolk. After three weeks, the little krill has finished the 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 (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 ecdysis in order to grow. Approximately every 13 to 20 days krill shed their chitin skin and leave it behind as exuvia.
==Food== [[Image:Kilsheadkils.jpg|200px|right|thumb|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 to be shining in green through the animal's 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'' [http://www.ecoscope.com/krill/filter/index.htm]. The glass shells of the diatoms are cracked in the "gastric mill" and then digested in the hepatopancreas. They 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 left in the feces (see below). In aquaria, krill have been observed eating each other. When they are not fed in aquaria, they shrink in size after molting, which is exceptional for animals the size of krill. Likely this is an adaptation to the seasonality of their food supply, which is mostly limited in the dark winter months under the ice.
===Filter feeding=== :Image:Filterkrillkils2.gif_(from_300_frames/sec;_490kB)_is_also_available.">Image:Krill filter feeding.jpg|right|thumb|180px|Krill feeding under high phytoplankton concentration. A :Image:Filterkrillkils2.gif (from 300 frames/sec; 490kB) is also available. ''Main article: Filter feeder.'' The Antarctic krill manages to directly utilize the minute phytoplankton cells, which no other higher animal of krill size can do. This is accomplished through filter feeding, using the krill's highly developed front legs, providing for a very efficient filtering apparatus: the six thoracopods form a very effective "feeding basket" used to collect phytoplankton from the open water. In the finest areas the openings are only 1 micrometer. SEM images of this amazing stucture can be studied [http://en.wikipedia.org/wiki/Filter_feeder#Details_of_the_feeding_basket here]. In the movie linked to the right, 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, like in the ''in situ'' image below, and then the algae are combed to the mouth opening with special setae on the inner side of the thoracopods.
===Ice-algae raking=== [[Image:Krillicekils.jpg|right|thumb|200px|Antarctic Krill feeding off ice-algae - the surface of the ice on the left side is colored green - click in the image for larger views - this picture has been taken by a ROV]] Antarctic Krill can scrape off the green lawn of ice-algae from the underside of the pack ice [http://www.ecoscope.com/icecave2.htm]. The image to the right, taken via a ROV, 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. 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.
===The biological pump and carbon sequestration=== [[Image:Krillspitballkils3.jpg|thumb|200px|right|''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 middle (for higher resolution and history click into the image)]] 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 Carbon Sequestration it for about 1,000 years. 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=== Krill are often referred to as ''light-shrimp'' because they can emit light, produced by bioluminescence organs. These organs are located on various parts of the individual krill's body: one pair of organs at the eyestalk (c.f. the image of the head above), another pair on the hips of the 2nd and 7th 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. The krill's bioluminescent organs contain several fluorescent substances. The major component has a maximum fluorescence at an excitation of 355 Nanometre and emission of 510 nm.
===Escape reaction=== 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 per second. The trigger time to optical stimulus is, despite the low temperatures, only 55 milliseconds.
===The compound eye=== [[Image:Krilleyekils.jpg|right|thumb|200px|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. 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.
==Geographical distribution== [[Image:krilldistribution.jpg|thumb|200px|right|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 Ocean sector. The northern boundary of the Southern Ocean with its Atlantic, Pacific and Indian 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° Celsius. 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 eddy 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 be tagged yet to track 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, Seal (mammal), 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 Crabeater Seal 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; their diet consists to 98% of '' E. superba''. These seals consume over 63 million tonnes of krill each year. Leopard seals have developed similar teeth (45% krill in diet). All seals consume 63–130 million tonnes, all whales 34–43 million tonnes, the birds 15–20 million tonnes, the squids 30–100 million tonnes, and the fish 10–20 million tonnes, adding up to 152–313 million tonnes of krill consumption each year. The size step between krill and its prey is unusually large: generally it takes three or four steps from the 20 micrometer-tiny phytoplankton cells to a krill-sized organism (via small copepods, large copepods, mysids to 5 cm fish). 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. ===Biomass and Production=== The Antarctic krill's biomass is estimated to be between 1 E11 kg tonnes, making ''E. superba'' the most successful animal species on the Earth. 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. 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 the largest plankton assemblages in the world, possibly the largest. It 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. Thus primary production range between 1 and 2 g carbon per square meter, this, however, is not an outstanding production. Close to the ice it can reach 30–50 g carbon per square meter, but the area of good production is just enormous, and in the Austral summer there are many hours of daylight.
===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. 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 is substituted by Salps. ===Fisheries=== [[Image:krillcatch.gif|thumb|240px|right|Annual world catch of ''E. superba'', compiled from FAO data.]] ''Main article: Krill fishery.'' The fishery of the 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, as it has a very high Drag (physics), producing a bow wave that deflects 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 exploded while fishing through the krill schools. 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.
==Future visions and ocean engineering== Despite the scarce 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 [http://www.palomar.edu/oceanography/iron.htm]. 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 [http://www.chooseclimate.org/cleng/cleng.html]. 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 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.
== Notes == This species is often misspelled ''Euphasia superba'' [http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&q=%22euphasia+superba%22&btnG=Google+Search] or ''Eupausia superba'' [http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&q=%22eupausia+superba%22&btnG=Google+Search]. ==References== * Atkinson, A.; Siegel, V.; Pakhomov, E.; Rothery, P.: ''[http://www.nature.com/nature/journal/v432/n7013/abs/nature02996_fs.html Long-term decline in krill stock and increase in salps within the Southern Ocean]''. In ''Nature (journal)'' 432:100-103; 2004. * Bonner, B.: ''Birds and Mammals - Antarctic Seals'', in Buckley, R.: ''Antarctica''; Pergamon Press 1995, pp. 202 – 222. * Everson, I.; Agnew D. J.; Miller, D. G. M.: ''Krill fisheries and the future.'' In Everson, I. (ed.): ''Krill: biology, ecology and fisheries.'' Oxford, Blackwell Science, 345-348; 2000. * FAO: [http://www.fao.org/figis/servlet/species?fid=3393 Species Fact Sheet ''Euphausia superba'']. Accessed Jun 16, 2005. * Gross, L.: ''[http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0030127 As the Antarctic Ice Pack Recedes, a Fragile Ecosystem hangs in the Balance]''. Public Library of Science; PLoS Biol 3(4):127; 2005. * Hamner, W. M.; Hamner, P. P.; Strand, S. W.; Gilmer, R. W.: ''Behavior of Antarctic Krill, ''Euphausia superba'': Chemoreception, Feeding, Schooling and Molting''; Science (journal) 220, pp. 433 – 435; 1983. * Harvey, H. R.; Se-Jong Ju: [http://www.ccpo.odu.edu/Research/globec/3sciinvest/harvey.htm ''Biochemical Determination of Age Structure and Diet History of the Antarctic Krill, ''Euphausia superba,'' during Austral Winter'']; [http://www.ccpo.odu.edu/Research/globec/3sciinvest/menu.html Third U.S. Southern Ocean GLOBEC Science Investigator Meeting]; Arlington, 2001. * Kils, U.; Klages, N: ''Der Krill''. Naturwissenschaftliche Rundschau 10:397-402, 1979. (English translation: ''[http://wikisource.org/wiki/Author:Uwe_Kils/klages/part1 The Krill]'') * Kils, U.: [http://wikisource.org/wiki/Author:Uwe_Kils/biomass3/part1 ''Swimming behavior, Swimming Performance and Energy Balance of Antarctic Krill ''Euphausia superba''.''] BIOMASS Scientific Series 3, BIOMASS Research Series, 1-122; 1982. * Kils, U.: [http://wikisource.org/wiki/Author:Uwe_Kils/polar/part1 ''Swimming and feeding of Antarctic Krill, ''Euphausia superba'' - some outstanding energetics and dynamics - some unique morphological details'']. In ''Berichte zur Polarforschung'', Alfred Wegener Institute for Polar and Marine Research, Special Issue 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.; Marshall, P.: ''[http://wikisource.org/wiki/Author:Uwe_Kils/hempel/part1 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 1995; pp. 201-210. ISBN 3-334-60950-2. * Loeb, V.; Siegel, V.; Holm-Hansen, O.; Hewitt, R.; Fraser, W., ''et al.'': ''Effects of sea-ice extent and krill or salp dominance on the Antarctic food web''. Nature 387:897-900; 1997. * Marr, J. W. S.: ''The natural history and geography of the Antarctic Krill ''Euphausia superba''.'' Discovery report 32:33-464; 1962. * Marschall, P.: ''The overwintering strategy of Antarctic krill under the pack ice of the Weddell Sea'', Polar Biol 9;129-135; 1988 * Miller, D. G. and Hampton, I.: ''Biology and Ecology of the Antarctic Krill (''Euphausia superba'' Dana): a review''. BIOMASS Scientific Series 9, pp. 1 – 66; 1989. * Nicol, S.; Endo, Y.: ''[http://www.fao.org/documents/show_cdr.asp?url_file=//DOCREP/003/W5911E/w5911e00.htm Krill Fisheries of the World]'', FAO Fisheries Technical Paper 367; 1997. * Ross, R. M.; Quetin, L. B.: ''How Productive are Antarctic Krill?'' Bioscience 36, pp. 264 – 269; 1986. * Hyoung-Chul Shin; Nicol, S.: [http://www.int-res.com/abstracts/meps/v239/p157-167.html ''Using the relationship between eye diameter and body length to detect the effects of long-term starvation on Antarctic krill ''Euphausia superba''.''] Mar Ecol Progress Series (MEPS) 239:157-167; 2002. ==Further reading== * Hempel, I.; Hempel, G.: ''Field observations on the developmental ascent of larval ''Euphausia superba'' (Crustacea)''. Polar Biol 6; pp. 121 – 126; 1986. * Hempel, G.: ''Antarctic marine food webs''. In Siegfried, W. R.; Condy, P. R.; Laws, R. M. (eds): ''Antarctic nutrient cycles and food webs''. Springer-Verlag, Berlin, pp. 266 – 270; 1985. * Hempel, G.: ''The krill-dominated pelagic system of the Southern Ocean''. Envir. Inter. 13, pp. 33 – 36; 1987. * Hempel, G.: ''Life in the Antarctic sea ice zone''. Polar Record 27(162); pp. 249 – 253; 1991 * Hempel, G.; Sherman, K.: ''Large marine ecosystems of the world: trends in exploitation, protection, and research''. Elsevier, Amsterdam: Large marine ecosystems 12, 423 pp; 2003 * Mauchline, J.; Fisher, L.R.: ''The biology of euphausiids.'' Adv. Mar. Biol. 7; 1969. * Nicol, S.; Foster, J.: ''[http://www.edpsciences.org/articles/alr/pdf/2003/01/alr3065.pdf?access=ok Recent trends in the fishery for Antarctic krill]'', Aquat. Living Resour. 16, pp. 42 – 45; 2003. * Quetin, L. B., Ross, R. M. and Clarke, A.: ''Krill energetics: seasonal and environmental aspects of the physiology of ''Euphausia superba. In El-Sayed, S. Z. (ed.): ''Southern Ocean Ecology: the BIOMASS perspective'', pp. 165 – 184. Cambridge University Press, 1994. * Sahrhage, D.: ''Antarctic Krill Fisheries: Potential Resources and Ecological Concerns.'' In Caddy, J. F. (ed.): ''Marine Invertebrate Fisheries; their assessment and management''; pp. 13 – 33. Wiley, 1989. == External links == * [http://www.marinebio.com/species.asp?id=518 ''Euphausia superba''] from ''MarineBio''. * [http://www.ecoscope.com/krill "Virtual microscope"] of Antarctic krill for an interactive tour of their morphology and behavior, along with other peer-reviewed information. * [http://wikisource.org/wiki/Author:Uwe_Kils High resolution images] at Wikisource. * [http://earthobservatory.nasa.gov/Study/UpperCrust/ "Krill fights for survival as sea ice melts"] from the NASA's "Earth Observatory". * [http://news.nationalgeographic.com/news/2003/08/0805_030805_antarctic.html "Antarctic Wildlife at Risk From Overfishing, Experts Say"], from ''National Geographic'' News, August 5, 2003. * [http://www.antarctica.ac.uk/Living_and_Working/Diaries/RRS_James_Clark_Ross/antarctic2002_2003/jrupdate12_16.html Diary] of the RRS ''James Clark Ross'', giving a popular introduction to the Antarctic krill. *[http://www.antarctica.ac.uk/BAS_Science/Highlights/2000/less_krill.html "Less krill for predators in the Southern Ocean"] from the British Antarctic Survey. See also [http://news.bbc.co.uk/1/hi/sci/tech/1445754.stm "Climate row touches blue whales"], from the BBC, July 19, 2001. * [http://www.aad.gov.au/default.asp?casid=1143 A time to krill] * [http://wikisource.org/wiki/Miscellaneous_material/krill_literature Extensive bibliography]. Crustaceans
after much discussion I want to re-enter this article. All [http://en.wikipedia.org/wiki/Wikipedia:Featured_article_candidates/Antarctic_krill objections and suggestions and language] have been worked on, references added, some images moved to other places. An academic group from Australia, USA, Germany, Japan and Norway found no errors. Thanks go especially to user:lupo, User:Yakuzai and in Scandinavia to User:Salleman. The article covers the basic biology, ecology, geography, fisheries and some unique bio-features of this key species of Antarctica, which is probably (in terms of biomass) the most successfull animal of the planet, and gives an outlook for future ventures of Ocean Engineering. ''Uwe_Kils''">User:Kils 21:57, Jun 20, 2005 (UTC) ---- ==POV?== Is the statement :''In the North Atlantic, Meganyctiphanes norvegica and in the Pacific, Euphausia pacifica are important krill species.'' specifically the word "important", not POV? -- User:Timwi 15:34, 15 Feb 2004 (UTC) == Vote: move == This page is ''de facto'' about Antarctic Krill rather than krill in general. I updated the intro paragraph, but I propose to move this article to Antarctic krill and have krill redirect to either Euphausiid or krill (disambiguation). Quick vote: * Yes, move the page. User:One-dimensional Tangent (User talk:One-dimensional Tangent) 01:54, 20 May 2005 (UTC) * Yes, but move it to Antarctic Krill (note capitalization). - User:UtherSRG 03:04, May 20, 2005 (UTC) *Move to Antarctic K/krill, and move Krill (disambiguation to Krill. User:Sjorford User talk:Sjorford 11:48, 21 May 2005 (UTC) == Hard to understand== Really like what you have done with the article, i think it could be really good but i have difficulty understanding some of it. As a native English speaker i found some of the grammar quite poor which made some of the content unintelligable. Also the choice and the way you word the sentences has made it difficult for me to understand what is being conveyed. I have made some minor edits to some of the wording but i still think it needs a bit of work. Again i think this is a good article but with better elucidation and grammar it could be a fantastic article. User:Yakuzai 21:14, 12 Jun 2005 (UTC) ::hallo Yakuzai! thank you for your comment. Please help us and change bad language. I am German and know my English is rotten - take care User:Kils 21:20, Jun 12, 2005 (UTC) Hi Kils. Have read through your article more thoroughly and have done some further editing. Will go through it systematically over the next week or two, really want this to be a featured article! Here are some initial thoughts on the introduction: 1. The bit about the step between prey and predator is hard to understand maybe you could write this up more thouroughly in the ecosystem section and erase it from introduction. 2. In the section Systematic are you trying to give an account of what distinguishes the Antartic Krill from others of the same order? If so i Think you need to state that and also have a link for the meaning of carapax and gnathapod. Peolple who don't have knowledge of technical terms like these will find it hard to understand this section. I made an edit of this section myself but i need to clarify whether you are trying to say that the visibility of the gills is due to the thoracomers on each side of the carapax being so short? Also whether the visibility of the gills is another distinguishing feature of this order? updated by User:193.115.13.66 12:01, 13 Jun 2005 (UTC) Hopefully this is helpful for you. User:Yakuzai 22:45, 12 Jun 2005 (UTC) ::thank you, Yakuzai, I will work on it User:Kils 23:27, Jun 12, 2005 (UTC) The article needs to be restructured. I suggest reducing the number of top-level sections by grouping most of current sections under "Biology" and "Ecology". I believe the re-sorting would also make the text flow more naturally. Another thing, which would be helpful for editors and readers alike, would be short explanations of specialized terms in ()'s, when those are first used (especially for those that are now red links). User:Zocky 20:51, 13 Jun 2005 (UTC) == The filter-feeding movie == I've gone ahead and implemented my own suggestion: replacing the movie with a still image plus a link to the full movie. I hope you can live with that, but having the full animation inline made editing very tedious for me due to the long load time, and I also find animations distracting when I want to read the text. The caption says "slow motion" at 300 frames/sec. The GIF contains 10 frames, each displaying for 40 ms. That is, it replays 25 frames/sec. Why not say "slowed down by a factor of 12"? User:Lupo 14:39, 14 Jun 2005 (UTC) == The eye == Some ideas on how to expand that section: How large is the eye? What's the size of the individual components (or whatever they're called)? How many of them are there? Is its light sensitivity known? Do rely krill on their vision much?`Is that known at all? or do they start their escape reaction based on sensing changes in the microcurrents around them? User:Lupo 15:48, 14 Jun 2005 (UTC) == Small points == Just a few small points that are causing me a few problems when i read this article, they are, 1: the prose in the section "Position in Antartic Ecosystem" is quite awkward, i think maybe this could be worded better and grammar improved. 2: The overall feel that the article sometimes reads as though it is about Krill in general as oppose to Antartic Krill specifically. 3: I am in agreement with Lupo that the section on the compound eye should be expanded, as at the moment it just seems like an after thought that has been tagged on to fill up space. Other than that i think evereyone involved has done a fantastic job! User:Yakuzai 21:33, 14 Jun 2005 (UTC) ==thank you everybody== I would like to express my thanks to everybody helping in the nomination. I think 3 1/2 supports and a long long discussion are an unexpected and great outcome for a critter so remote and unknown - you should see how little and poor Antarctic krill is represented in Encarta and Britannica - this is the best reviewed and resourced general article of krill we know of - it is impossible to fullfill all wishes at the same time - this is what we did with our all product [http://en.wikipedia.org/w/index.php?title=Antarctic_krill&oldid=15197713 peer review stamp] to qualify this stage of the article for academic exercises, especially for our dreams of a Virtual university within Wikiversity - good luck to you all User:Kils 21:48, Jun 14, 2005 (UTC) == Vertical migration == Northern krill seems to move down during the day and up again at night (see [http://www.le.ac.uk/biology/gat/krill.html]). Is this a behavior common to all krill? If yes, I think this should be added to the article on krill in general. (That article, BTW, needs expansion!) In no, does the Antarctic krill also show this behavior? If so, what is known about the causes? Is it just that their food sinks and rises, or are there other factors? User:Lupo 07:27, 15 Jun 2005 (UTC) ::yes, they also do that User:Kils 12:12, Jun 15, 2005 (UTC) == The MarineBio page == at [http://www.marinebio.com/species.asp?id=518] looks like a good source. Has a description that is probably more accessible to laypeople, and some facts we might add. Three points: ::good idea to do that User:Kils 12:12, Jun 15, 2005 (UTC) *The image they have seems to be essentially the same as our top image. Theirs looks a bit sharper; did they post-process it? Also, they say © Alfred Wegener Institute for Polar and Marine Research! ::I gave them the image for their sci and edu collection, not the copyright (I worked there as a Heisenberg Fellow for a while). If people ask the AWI for the krill image they charge high royalties (and the new administration about always forgets to share them with me), at Wikipedia everybody gets it free since 16:58, Apr 1, 2003. I took this quantitative sci picture long before the AWI was founded. You can contact Gotthilf Hempel about the copyright or [http://maps.google.com/maps?ll=39.48080778121948,-74.5048463344574&spn=0.0054931640625,0.00685572624206543&t=k&hl=en visit] me and I show you my original 60 mm film (I pick you up at the airport, than we can talk wiki). This picture and the revenue from it and the Maier Leinitz Prize upon it helped raise the political motion for hatching the AWI and instrumentation for the ''in situ'' images and videos (developed at the ATOLL laboratory). We are the only ones in the world with such high res ''in situ'' material, invited all over the world to talk about it. The high resolution image you can view via my [http://www.ecoscope.com//krill/krill6/index.htm eco''SCOPE''.com] server. This image was the first critter on the web ever, hatching from the first NeXT in Kiel University. :::Hey, I wasn't questioning ''your'' copyright. I rather had the impression that ''their'' attribution was wrong! User:Lupo 13:09, 15 Jun 2005 (UTC) ::::I ask them occasionaly to take the C sign out of the image (some overeager administrator put it there) and link the image to the virtual microscope, but they are slow (and in the small group of Antarctic scientists all over the world we are all friends) - and who cares? *They say swarms can be as dense as 10,000 individuals per m³; our article claims 20,000. Which number is correct, and what's the source for our number? ::lets write 10 000 to 30 000 - there is a lot of discussion and just about no knowledge about the issue, that is not so easy to measure User:Kils 12:12, Jun 15, 2005 (UTC) *They say that Poland and Ukraine are active in krill fishery, too. ::would be nice if you would add itUser:Kils 12:12, Jun 15, 2005 (UTC) User:Lupo 08:17, 15 Jun 2005 (UTC) == Things to move over to krill == I agree with User:Yakuzai that some sections are probably better moved over to krill. In particular, I have the impression that the "Fisheries" and "Future visions of ocean engineering" sections should go there. User:Lupo 08:44, 15 Jun 2005 (UTC) ::no, this is only about E. superba User:Kils 12:12, Jun 15, 2005 (UTC) ==image request== As requested I uploaded a translated graph Image:Krillanatomykils.jpg (by Kils & Klages) (It was available as gfdl all the time on the wikisource links, where i put some of our publications with full res images, just click on the names in the refs - nobody aparently noticed that (thats the way we work: short articles with lots of attached original material for in depth readings) User:Kils 12:12, Jun 15, 2005 (UTC) :Thanks a lot! (Hmmm... I had been visiting the Wikisource pages, but also the pages on your own site. Must have missed that one.) User:Lupo 13:12, 15 Jun 2005 (UTC) ::Very intelligable. Nicely done! User:El C ==response from London== Uwe wants to share this with you (from his talk page): ===Hello Kils=== Just would like to state that i have very much enjoyed being involved in a project of this nature. To see the speed of co-operation between various people was (Uwe, Lupo and Salleman and all others) fantastic. It was a complete buzz to go off researching about a scientific subject and coming to some understanding and appreciation of a creature that i would have no knowledge or interest in otherwise. I would like to say that it takes a damn good teacher to get others interested in what they teach and i for one, if only in a rudimentary and general way have found the subject of Krill and sorrounding issues of ecology and environment fascinating. I think that says a lot about your willingness to let others participate in something which you obviously have great knowledge in and could easily have been a lot less humble with. At some point i will put up some informtion on my home page so at least people know a little more about me. Am going to try to extend the article on Ice-algae so any info you may have would be good. I hope the article on Antartic Krill gets featured as i think it is now very good. Wikiversity sounds like a good idea but will need more time to go through the proposal (not too sure what help i could be). Once again thanks Uwe! User:Yakuzai 22:50, 20 Jun 2005 (UTC) that feels good ''Uwe_Kils''">User:Kils 03:25, Jun 21, 2005 (UTC) ===Biomass=== Just looked over the expanded biomass section and have made some edits but their are a few sentences that i think need clarifying. "The total non-krill yield from all world fisheries is about 100 million tonnes per year whilst estimates of annual Antarctic krill production are between 13 million to several billion tonnes per year". 1. By "Antarctic Krill production" do you mean the annual yield of antarctic krill from fisheries? :::no, it is the growth of biomass over a year - amazingly high, isn't it - what I read over my life about krill and our in situ imaging of schools my personal oppinion is that the biomass numbers are even an underestimation. ''Uwe_Kils''">User:Kils 20:10, Jun 21, 2005 (UTC) If this is not the case then is the above comparison valid? 2. "Several billion tonnes per year" would seem to contradict the opening paragraph's claim of a total biomass of 500 million tonnes. "Thus primary production falls within 1 -2 g carbon per square meter, this however is not a very high concentration if compared to the 30 - 50 g carbon per square meter close to the ice. but the area is just enormous, and in the summer there are many hours of daylight". 3. I think these last few sentences need work, wish i could be more specific. User:Yakuzai 19:32, 21 Jun 2005 (UTC)
See other meanings of words starting from letter:
Words begining with Antarctic_krill:
Antarctic_Krill
Antarctic_Krill
Antarctic_krill
Antarctic_krill
Antarctic_krill_filter
Antarctic_krill_head
Antarctic Krill
#redirect Antarctic krill
Antarctic Krill
#redirect Talk:Antarctic krill
Antarctic krill
The Antarctic krill (''Euphausia superba'' ) is a species of krill found in the Antarctica waters of the Southern Ocean. Antarctic krill (shrimp-like invertebrates) live in large schools, called swarms, sometimes reaching densities of 10,000–30,000 individual animals per cubic meter. They feed directly on minute phytoplankton, thereby using the primary production energy originally derived from the sun in order to sustain their pelagic life cycle. They grow to a length of 6 cm, weigh up to 2 grams, and can live for up to six years. They are the key species in the Antarctic ecosystem and are probably, in terms of biomass, the most successful animal species on the planet (~500 million tonnes). ==Systematics== All members of the euphausiacea 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 the Antartic krill visible to the human eye. The thoracopod do not form a gnathopod, which differentiates this order from the decapoda. (''See also [http://species.wikipedia.org/wiki/Euphausia_superba ''Euphausia superba'' at Wikispecies].'') ==Life history== The main spawning time of Antarctic krill is from January through 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 of the male are constructed as tools. Females lay 6,000–10,000 eggs at one time. They are fertilised as they pass out of the genital opening by sperm liberated from spermatophores which have been attached by the males. According to the classical hypothesis of Marr, derived from the results of the expedition of the famous British research vessel "Discovery", egg development then proceeds 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 2,000–3,000 m. From the time the egg hatches, the 1st Nauplius_(larva) (i.e., larval stage) starts migrating towards the surface with the aid of its three pairs of legs; the so-called ''developmental ascent''. The next two larval stages, termed 2nd nauplius and metanauplius, still do not eat but are nourished by the remaining yolk. After three weeks, the little krill has finished the 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 (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 ecdysis in order to grow. Approximately every 13 to 20 days krill shed their chitin skin and leave it behind as exuvia.
==Food== [[Image:Kilsheadkils.jpg|200px|right|thumb|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 to be shining in green through the animal's 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'' [http://www.ecoscope.com/krill/filter/index.htm]. The glass shells of the diatoms are cracked in the "gastric mill" and then digested in the hepatopancreas. They 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 left in the feces (see below). In aquaria, krill have been observed eating each other. When they are not fed in aquaria, they shrink in size after molting, which is exceptional for animals the size of krill. Likely this is an adaptation to the seasonality of their food supply, which is mostly limited in the dark winter months under the ice.
===Filter feeding=== :Image:Filterkrillkils2.gif_(from_300_frames/sec;_490kB)_is_also_available.">Image:Krill filter feeding.jpg|right|thumb|180px|Krill feeding under high phytoplankton concentration. A :Image:Filterkrillkils2.gif (from 300 frames/sec; 490kB) is also available. ''Main article: Filter feeder.'' The Antarctic krill manages to directly utilize the minute phytoplankton cells, which no other higher animal of krill size can do. This is accomplished through filter feeding, using the krill's highly developed front legs, providing for a very efficient filtering apparatus: the six thoracopods form a very effective "feeding basket" used to collect phytoplankton from the open water. In the finest areas the openings are only 1 micrometer. SEM images of this amazing stucture can be studied [http://en.wikipedia.org/wiki/Filter_feeder#Details_of_the_feeding_basket here]. In the movie linked to the right, 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, like in the ''in situ'' image below, and then the algae are combed to the mouth opening with special setae on the inner side of the thoracopods.
===Ice-algae raking=== [[Image:Krillicekils.jpg|right|thumb|200px|Antarctic Krill feeding off ice-algae - the surface of the ice on the left side is colored green - click in the image for larger views - this picture has been taken by a ROV]] Antarctic Krill can scrape off the green lawn of ice-algae from the underside of the pack ice [http://www.ecoscope.com/icecave2.htm]. The image to the right, taken via a ROV, 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. 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.
===The biological pump and carbon sequestration=== [[Image:Krillspitballkils3.jpg|thumb|200px|right|''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 middle (for higher resolution and history click into the image)]] 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 Carbon Sequestration it for about 1,000 years. 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=== Krill are often referred to as ''light-shrimp'' because they can emit light, produced by bioluminescence organs. These organs are located on various parts of the individual krill's body: one pair of organs at the eyestalk (c.f. the image of the head above), another pair on the hips of the 2nd and 7th 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. The krill's bioluminescent organs contain several fluorescent substances. The major component has a maximum fluorescence at an excitation of 355 Nanometre and emission of 510 nm.
===Escape reaction=== 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 per second. The trigger time to optical stimulus is, despite the low temperatures, only 55 milliseconds.
===The compound eye=== [[Image:Krilleyekils.jpg|right|thumb|200px|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. 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.
==Geographical distribution== [[Image:krilldistribution.jpg|thumb|200px|right|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 Ocean sector. The northern boundary of the Southern Ocean with its Atlantic, Pacific and Indian 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° Celsius. 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 eddy 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 be tagged yet to track 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, Seal (mammal), 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 Crabeater Seal 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; their diet consists to 98% of '' E. superba''. These seals consume over 63 million tonnes of krill each year. Leopard seals have developed similar teeth (45% krill in diet). All seals consume 63–130 million tonnes, all whales 34–43 million tonnes, the birds 15–20 million tonnes, the squids 30–100 million tonnes, and the fish 10–20 million tonnes, adding up to 152–313 million tonnes of krill consumption each year. The size step between krill and its prey is unusually large: generally it takes three or four steps from the 20 micrometer-tiny phytoplankton cells to a krill-sized organism (via small copepods, large copepods, mysids to 5 cm fish). 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. ===Biomass and Production=== The Antarctic krill's biomass is estimated to be between 1 E11 kg tonnes, making ''E. superba'' the most successful animal species on the Earth. 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. 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 the largest plankton assemblages in the world, possibly the largest. It 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. Thus primary production range between 1 and 2 g carbon per square meter, this, however, is not an outstanding production. Close to the ice it can reach 30–50 g carbon per square meter, but the area of good production is just enormous, and in the Austral summer there are many hours of daylight.
===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. 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 is substituted by Salps. ===Fisheries=== [[Image:krillcatch.gif|thumb|240px|right|Annual world catch of ''E. superba'', compiled from FAO data.]] ''Main article: Krill fishery.'' The fishery of the 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, as it has a very high Drag (physics), producing a bow wave that deflects 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 exploded while fishing through the krill schools. 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.
==Future visions and ocean engineering== Despite the scarce 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 [http://www.palomar.edu/oceanography/iron.htm]. 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 [http://www.chooseclimate.org/cleng/cleng.html]. 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 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.
== Notes == This species is often misspelled ''Euphasia superba'' [http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&q=%22euphasia+superba%22&btnG=Google+Search] or ''Eupausia superba'' [http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&q=%22eupausia+superba%22&btnG=Google+Search]. ==References== * Atkinson, A.; Siegel, V.; Pakhomov, E.; Rothery, P.: ''[http://www.nature.com/nature/journal/v432/n7013/abs/nature02996_fs.html Long-term decline in krill stock and increase in salps within the Southern Ocean]''. In ''Nature (journal)'' 432:100-103; 2004. * Bonner, B.: ''Birds and Mammals - Antarctic Seals'', in Buckley, R.: ''Antarctica''; Pergamon Press 1995, pp. 202 – 222. * Everson, I.; Agnew D. J.; Miller, D. G. M.: ''Krill fisheries and the future.'' In Everson, I. (ed.): ''Krill: biology, ecology and fisheries.'' Oxford, Blackwell Science, 345-348; 2000. * FAO: [http://www.fao.org/figis/servlet/species?fid=3393 Species Fact Sheet ''Euphausia superba'']. Accessed Jun 16, 2005. * Gross, L.: ''[http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0030127 As the Antarctic Ice Pack Recedes, a Fragile Ecosystem hangs in the Balance]''. Public Library of Science; PLoS Biol 3(4):127; 2005. * Hamner, W. M.; Hamner, P. P.; Strand, S. W.; Gilmer, R. W.: ''Behavior of Antarctic Krill, ''Euphausia superba'': Chemoreception, Feeding, Schooling and Molting''; Science (journal) 220, pp. 433 – 435; 1983. * Harvey, H. R.; Se-Jong Ju: [http://www.ccpo.odu.edu/Research/globec/3sciinvest/harvey.htm ''Biochemical Determination of Age Structure and Diet History of the Antarctic Krill, ''Euphausia superba,'' during Austral Winter'']; [http://www.ccpo.odu.edu/Research/globec/3sciinvest/menu.html Third U.S. Southern Ocean GLOBEC Science Investigator Meeting]; Arlington, 2001. * Kils, U.; Klages, N: ''Der Krill''. Naturwissenschaftliche Rundschau 10:397-402, 1979. (English translation: ''[http://wikisource.org/wiki/Author:Uwe_Kils/klages/part1 The Krill]'') * Kils, U.: [http://wikisource.org/wiki/Author:Uwe_Kils/biomass3/part1 ''Swimming behavior, Swimming Performance and Energy Balance of Antarctic Krill ''Euphausia superba''.''] BIOMASS Scientific Series 3, BIOMASS Research Series, 1-122; 1982. * Kils, U.: [http://wikisource.org/wiki/Author:Uwe_Kils/polar/part1 ''Swimming and feeding of Antarctic Krill, ''Euphausia superba'' - some outstanding energetics and dynamics - some unique morphological details'']. In ''Berichte zur Polarforschung'', Alfred Wegener Institute for Polar and Marine Research, Special Issue 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.; Marshall, P.: ''[http://wikisource.org/wiki/Author:Uwe_Kils/hempel/part1 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 1995; pp. 201-210. ISBN 3-334-60950-2. * Loeb, V.; Siegel, V.; Holm-Hansen, O.; Hewitt, R.; Fraser, W., ''et al.'': ''Effects of sea-ice extent and krill or salp dominance on the Antarctic food web''. Nature 387:897-900; 1997. * Marr, J. W. S.: ''The natural history and geography of the Antarctic Krill ''Euphausia superba''.'' Discovery report 32:33-464; 1962. * Marschall, P.: ''The overwintering strategy of Antarctic krill under the pack ice of the Weddell Sea'', Polar Biol 9;129-135; 1988 * Miller, D. G. and Hampton, I.: ''Biology and Ecology of the Antarctic Krill (''Euphausia superba'' Dana): a review''. BIOMASS Scientific Series 9, pp. 1 – 66; 1989. * Nicol, S.; Endo, Y.: ''[http://www.fao.org/documents/show_cdr.asp?url_file=//DOCREP/003/W5911E/w5911e00.htm Krill Fisheries of the World]'', FAO Fisheries Technical Paper 367; 1997. * Ross, R. M.; Quetin, L. B.: ''How Productive are Antarctic Krill?'' Bioscience 36, pp. 264 – 269; 1986. * Hyoung-Chul Shin; Nicol, S.: [http://www.int-res.com/abstracts/meps/v239/p157-167.html ''Using the relationship between eye diameter and body length to detect the effects of long-term starvation on Antarctic krill ''Euphausia superba''.''] Mar Ecol Progress Series (MEPS) 239:157-167; 2002. ==Further reading== * Hempel, I.; Hempel, G.: ''Field observations on the developmental ascent of larval ''Euphausia superba'' (Crustacea)''. Polar Biol 6; pp. 121 – 126; 1986. * Hempel, G.: ''Antarctic marine food webs''. In Siegfried, W. R.; Condy, P. R.; Laws, R. M. (eds): ''Antarctic nutrient cycles and food webs''. Springer-Verlag, Berlin, pp. 266 – 270; 1985. * Hempel, G.: ''The krill-dominated pelagic system of the Southern Ocean''. Envir. Inter. 13, pp. 33 – 36; 1987. * Hempel, G.: ''Life in the Antarctic sea ice zone''. Polar Record 27(162); pp. 249 – 253; 1991 * Hempel, G.; Sherman, K.: ''Large marine ecosystems of the world: trends in exploitation, protection, and research''. Elsevier, Amsterdam: Large marine ecosystems 12, 423 pp; 2003 * Mauchline, J.; Fisher, L.R.: ''The biology of euphausiids.'' Adv. Mar. Biol. 7; 1969. * Nicol, S.; Foster, J.: ''[http://www.edpsciences.org/articles/alr/pdf/2003/01/alr3065.pdf?access=ok Recent trends in the fishery for Antarctic krill]'', Aquat. Living Resour. 16, pp. 42 – 45; 2003. * Quetin, L. B., Ross, R. M. and Clarke, A.: ''Krill energetics: seasonal and environmental aspects of the physiology of ''Euphausia superba. In El-Sayed, S. Z. (ed.): ''Southern Ocean Ecology: the BIOMASS perspective'', pp. 165 – 184. Cambridge University Press, 1994. * Sahrhage, D.: ''Antarctic Krill Fisheries: Potential Resources and Ecological Concerns.'' In Caddy, J. F. (ed.): ''Marine Invertebrate Fisheries; their assessment and management''; pp. 13 – 33. Wiley, 1989. == External links == * [http://www.marinebio.com/species.asp?id=518 ''Euphausia superba''] from ''MarineBio''. * [http://www.ecoscope.com/krill "Virtual microscope"] of Antarctic krill for an interactive tour of their morphology and behavior, along with other peer-reviewed information. * [http://wikisource.org/wiki/Author:Uwe_Kils High resolution images] at Wikisource. * [http://earthobservatory.nasa.gov/Study/UpperCrust/ "Krill fights for survival as sea ice melts"] from the NASA's "Earth Observatory". * [http://news.nationalgeographic.com/news/2003/08/0805_030805_antarctic.html "Antarctic Wildlife at Risk From Overfishing, Experts Say"], from ''National Geographic'' News, August 5, 2003. * [http://www.antarctica.ac.uk/Living_and_Working/Diaries/RRS_James_Clark_Ross/antarctic2002_2003/jrupdate12_16.html Diary] of the RRS ''James Clark Ross'', giving a popular introduction to the Antarctic krill. *[http://www.antarctica.ac.uk/BAS_Science/Highlights/2000/less_krill.html "Less krill for predators in the Southern Ocean"] from the British Antarctic Survey. See also [http://news.bbc.co.uk/1/hi/sci/tech/1445754.stm "Climate row touches blue whales"], from the BBC, July 19, 2001. * [http://www.aad.gov.au/default.asp?casid=1143 A time to krill] * [http://wikisource.org/wiki/Miscellaneous_material/krill_literature Extensive bibliography]. Crustaceans
Antarctic krill
after much discussion I want to re-enter this article. All [http://en.wikipedia.org/wiki/Wikipedia:Featured_article_candidates/Antarctic_krill objections and suggestions and language] have been worked on, references added, some images moved to other places. An academic group from Australia, USA, Germany, Japan and Norway found no errors. Thanks go especially to user:lupo, User:Yakuzai and in Scandinavia to User:Salleman. The article covers the basic biology, ecology, geography, fisheries and some unique bio-features of this key species of Antarctica, which is probably (in terms of biomass) the most successfull animal of the planet, and gives an outlook for future ventures of Ocean Engineering. ''Uwe_Kils''">User:Kils 21:57, Jun 20, 2005 (UTC) ---- ==POV?== Is the statement :''In the North Atlantic, Meganyctiphanes norvegica and in the Pacific, Euphausia pacifica are important krill species.'' specifically the word "important", not POV? -- User:Timwi 15:34, 15 Feb 2004 (UTC) == Vote: move == This page is ''de facto'' about Antarctic Krill rather than krill in general. I updated the intro paragraph, but I propose to move this article to Antarctic krill and have krill redirect to either Euphausiid or krill (disambiguation). Quick vote: * Yes, move the page. User:One-dimensional Tangent (User talk:One-dimensional Tangent) 01:54, 20 May 2005 (UTC) * Yes, but move it to Antarctic Krill (note capitalization). - User:UtherSRG 03:04, May 20, 2005 (UTC) *Move to Antarctic K/krill, and move Krill (disambiguation to Krill. User:Sjorford User talk:Sjorford 11:48, 21 May 2005 (UTC) == Hard to understand== Really like what you have done with the article, i think it could be really good but i have difficulty understanding some of it. As a native English speaker i found some of the grammar quite poor which made some of the content unintelligable. Also the choice and the way you word the sentences has made it difficult for me to understand what is being conveyed. I have made some minor edits to some of the wording but i still think it needs a bit of work. Again i think this is a good article but with better elucidation and grammar it could be a fantastic article. User:Yakuzai 21:14, 12 Jun 2005 (UTC) ::hallo Yakuzai! thank you for your comment. Please help us and change bad language. I am German and know my English is rotten - take care User:Kils 21:20, Jun 12, 2005 (UTC) Hi Kils. Have read through your article more thoroughly and have done some further editing. Will go through it systematically over the next week or two, really want this to be a featured article! Here are some initial thoughts on the introduction: 1. The bit about the step between prey and predator is hard to understand maybe you could write this up more thouroughly in the ecosystem section and erase it from introduction. 2. In the section Systematic are you trying to give an account of what distinguishes the Antartic Krill from others of the same order? If so i Think you need to state that and also have a link for the meaning of carapax and gnathapod. Peolple who don't have knowledge of technical terms like these will find it hard to understand this section. I made an edit of this section myself but i need to clarify whether you are trying to say that the visibility of the gills is due to the thoracomers on each side of the carapax being so short? Also whether the visibility of the gills is another distinguishing feature of this order? updated by User:193.115.13.66 12:01, 13 Jun 2005 (UTC) Hopefully this is helpful for you. User:Yakuzai 22:45, 12 Jun 2005 (UTC) ::thank you, Yakuzai, I will work on it User:Kils 23:27, Jun 12, 2005 (UTC) The article needs to be restructured. I suggest reducing the number of top-level sections by grouping most of current sections under "Biology" and "Ecology". I believe the re-sorting would also make the text flow more naturally. Another thing, which would be helpful for editors and readers alike, would be short explanations of specialized terms in ()'s, when those are first used (especially for those that are now red links). User:Zocky 20:51, 13 Jun 2005 (UTC) == The filter-feeding movie == I've gone ahead and implemented my own suggestion: replacing the movie with a still image plus a link to the full movie. I hope you can live with that, but having the full animation inline made editing very tedious for me due to the long load time, and I also find animations distracting when I want to read the text. The caption says "slow motion" at 300 frames/sec. The GIF contains 10 frames, each displaying for 40 ms. That is, it replays 25 frames/sec. Why not say "slowed down by a factor of 12"? User:Lupo 14:39, 14 Jun 2005 (UTC) == The eye == Some ideas on how to expand that section: How large is the eye? What's the size of the individual components (or whatever they're called)? How many of them are there? Is its light sensitivity known? Do rely krill on their vision much?`Is that known at all? or do they start their escape reaction based on sensing changes in the microcurrents around them? User:Lupo 15:48, 14 Jun 2005 (UTC) == Small points == Just a few small points that are causing me a few problems when i read this article, they are, 1: the prose in the section "Position in Antartic Ecosystem" is quite awkward, i think maybe this could be worded better and grammar improved. 2: The overall feel that the article sometimes reads as though it is about Krill in general as oppose to Antartic Krill specifically. 3: I am in agreement with Lupo that the section on the compound eye should be expanded, as at the moment it just seems like an after thought that has been tagged on to fill up space. Other than that i think evereyone involved has done a fantastic job! User:Yakuzai 21:33, 14 Jun 2005 (UTC) ==thank you everybody== I would like to express my thanks to everybody helping in the nomination. I think 3 1/2 supports and a long long discussion are an unexpected and great outcome for a critter so remote and unknown - you should see how little and poor Antarctic krill is represented in Encarta and Britannica - this is the best reviewed and resourced general article of krill we know of - it is impossible to fullfill all wishes at the same time - this is what we did with our all product [http://en.wikipedia.org/w/index.php?title=Antarctic_krill&oldid=15197713 peer review stamp] to qualify this stage of the article for academic exercises, especially for our dreams of a Virtual university within Wikiversity - good luck to you all User:Kils 21:48, Jun 14, 2005 (UTC) == Vertical migration == Northern krill seems to move down during the day and up again at night (see [http://www.le.ac.uk/biology/gat/krill.html]). Is this a behavior common to all krill? If yes, I think this should be added to the article on krill in general. (That article, BTW, needs expansion!) In no, does the Antarctic krill also show this behavior? If so, what is known about the causes? Is it just that their food sinks and rises, or are there other factors? User:Lupo 07:27, 15 Jun 2005 (UTC) ::yes, they also do that User:Kils 12:12, Jun 15, 2005 (UTC) == The MarineBio page == at [http://www.marinebio.com/species.asp?id=518] looks like a good source. Has a description that is probably more accessible to laypeople, and some facts we might add. Three points: ::good idea to do that User:Kils 12:12, Jun 15, 2005 (UTC) *The image they have seems to be essentially the same as our top image. Theirs looks a bit sharper; did they post-process it? Also, they say © Alfred Wegener Institute for Polar and Marine Research! ::I gave them the image for their sci and edu collection, not the copyright (I worked there as a Heisenberg Fellow for a while). If people ask the AWI for the krill image they charge high royalties (and the new administration about always forgets to share them with me), at Wikipedia everybody gets it free since 16:58, Apr 1, 2003. I took this quantitative sci picture long before the AWI was founded. You can contact Gotthilf Hempel about the copyright or [http://maps.google.com/maps?ll=39.48080778121948,-74.5048463344574&spn=0.0054931640625,0.00685572624206543&t=k&hl=en visit] me and I show you my original 60 mm film (I pick you up at the airport, than we can talk wiki). This picture and the revenue from it and the Maier Leinitz Prize upon it helped raise the political motion for hatching the AWI and instrumentation for the ''in situ'' images and videos (developed at the ATOLL laboratory). We are the only ones in the world with such high res ''in situ'' material, invited all over the world to talk about it. The high resolution image you can view via my [http://www.ecoscope.com//krill/krill6/index.htm eco''SCOPE''.com] server. This image was the first critter on the web ever, hatching from the first NeXT in Kiel University. :::Hey, I wasn't questioning ''your'' copyright. I rather had the impression that ''their'' attribution was wrong! User:Lupo 13:09, 15 Jun 2005 (UTC) ::::I ask them occasionaly to take the C sign out of the image (some overeager administrator put it there) and link the image to the virtual microscope, but they are slow (and in the small group of Antarctic scientists all over the world we are all friends) - and who cares? *They say swarms can be as dense as 10,000 individuals per m³; our article claims 20,000. Which number is correct, and what's the source for our number? ::lets write 10 000 to 30 000 - there is a lot of discussion and just about no knowledge about the issue, that is not so easy to measure User:Kils 12:12, Jun 15, 2005 (UTC) *They say that Poland and Ukraine are active in krill fishery, too. ::would be nice if you would add itUser:Kils 12:12, Jun 15, 2005 (UTC) User:Lupo 08:17, 15 Jun 2005 (UTC) == Things to move over to krill == I agree with User:Yakuzai that some sections are probably better moved over to krill. In particular, I have the impression that the "Fisheries" and "Future visions of ocean engineering" sections should go there. User:Lupo 08:44, 15 Jun 2005 (UTC) ::no, this is only about E. superba User:Kils 12:12, Jun 15, 2005 (UTC) ==image request== As requested I uploaded a translated graph Image:Krillanatomykils.jpg (by Kils & Klages) (It was available as gfdl all the time on the wikisource links, where i put some of our publications with full res images, just click on the names in the refs - nobody aparently noticed that (thats the way we work: short articles with lots of attached original material for in depth readings) User:Kils 12:12, Jun 15, 2005 (UTC) :Thanks a lot! (Hmmm... I had been visiting the Wikisource pages, but also the pages on your own site. Must have missed that one.) User:Lupo 13:12, 15 Jun 2005 (UTC) ::Very intelligable. Nicely done! User:El C ==response from London== Uwe wants to share this with you (from his talk page): ===Hello Kils=== Just would like to state that i have very much enjoyed being involved in a project of this nature. To see the speed of co-operation between various people was (Uwe, Lupo and Salleman and all others) fantastic. It was a complete buzz to go off researching about a scientific subject and coming to some understanding and appreciation of a creature that i would have no knowledge or interest in otherwise. I would like to say that it takes a damn good teacher to get others interested in what they teach and i for one, if only in a rudimentary and general way have found the subject of Krill and sorrounding issues of ecology and environment fascinating. I think that says a lot about your willingness to let others participate in something which you obviously have great knowledge in and could easily have been a lot less humble with. At some point i will put up some informtion on my home page so at least people know a little more about me. Am going to try to extend the article on Ice-algae so any info you may have would be good. I hope the article on Antartic Krill gets featured as i think it is now very good. Wikiversity sounds like a good idea but will need more time to go through the proposal (not too sure what help i could be). Once again thanks Uwe! User:Yakuzai 22:50, 20 Jun 2005 (UTC) that feels good ''Uwe_Kils''">User:Kils 03:25, Jun 21, 2005 (UTC) ===Biomass=== Just looked over the expanded biomass section and have made some edits but their are a few sentences that i think need clarifying. "The total non-krill yield from all world fisheries is about 100 million tonnes per year whilst estimates of annual Antarctic krill production are between 13 million to several billion tonnes per year". 1. By "Antarctic Krill production" do you mean the annual yield of antarctic krill from fisheries? :::no, it is the growth of biomass over a year - amazingly high, isn't it - what I read over my life about krill and our in situ imaging of schools my personal oppinion is that the biomass numbers are even an underestimation. ''Uwe_Kils''">User:Kils 20:10, Jun 21, 2005 (UTC) If this is not the case then is the above comparison valid? 2. "Several billion tonnes per year" would seem to contradict the opening paragraph's claim of a total biomass of 500 million tonnes. "Thus primary production falls within 1 -2 g carbon per square meter, this however is not a very high concentration if compared to the 30 - 50 g carbon per square meter close to the ice. but the area is just enormous, and in the summer there are many hours of daylight". 3. I think these last few sentences need work, wish i could be more specific. User:Yakuzai 19:32, 21 Jun 2005 (UTC)
See other meanings of words starting from letter:
A
AB | AC | AD | AE | AF | AG | AH | AI | AJ | AK | AL | AM | AN | AO | AP | AR | AS | AT | AU | AW | AX | AY | AZ |Words begining with Antarctic_krill:
Antarctic_Krill
Antarctic_Krill
Antarctic_krill
Antarctic_krill
Antarctic_krill_filter
Antarctic_krill_head
Sponsored links: praca.
These materials are based on Wikipedia and licensed under the GNU FDL
YouTube.com videos better site than Turbo Tax 2007
