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Krill

*** Shopping-Tip: Krill
{{otheruses}} {{Taxobox | color = pink | name = Euphausiacea | image = Meganyctiphanes norvegica2.jpg | image_width = 250px | image_caption = A Northern krill (''Meganyctiphanes norvegica'') | regnum = Animalia | phylum = Arthropoda | subphylum = Crustacea | classis = Malacostraca | superordo = Eucarida | ordo = '''Euphausiacea''' | ordo_authority = James Dwight Dana Dana, 1852 | subdivision_ranks = Family (biology) Families | subdivision = *Euphausiidae **''Euphausia'' Dana, 1852 **''Meganyctiphanes'' Ernest William Lyons Holt Holt and Walter Medley Tattersall W. M. Tattersall, 1905 **''Nematobrachion'' William Thomas Calman Calman, 1905 **''Nematoscelis'' Georg Sars G. O. Sars, 1883 **''Nyctiphanes'' G. O. Sars, 1883 **''Pseudeuphausia'' Hans Jacob Hansen Hansen, 1910 **''Stylocheiron'' G. O. Sars, 1883 **''Tessarabrachion'' Hansen, 1911 **''Thysanoessa'' Johann Friedrich von Brandt Brandt, 1851 **''Thysanopoda'' Pierre André Latreille Latreille, 1831 *Bentheuphausiidae **''Bentheuphausia amblyops'' }} '''Krill''' are shrimp-like marine invertebrate animals. These small crustaceans are important organisms of the zooplankton, particularly as food for baleen whales, Manta_ray Mantas, whale sharks, Crabeater seals and other pinniped seals, and a few seabird species that feed almost exclusively on them. Their scientific name is '''Euphausiids''', after their taxonomic Order (biology) order '''Euphausiacea'''. The name ''Krill'' comes from the Norwegian word ''krill'' meaning "young fry of fish". Krill occur in all oceans of the world. They are considered a keystone species near the bottom of the food chain because they feed on phytoplankton and zooplankton, converting these into a form suitable for many larger animals for whom krill makes up the largest part of their diet. Most of the species display large daily vertical migrations making a significant amount of biomass available as food for predators near the surface at night and in deeper waters during the day. Commercial fishing of krill is done in the Southern Ocean and in the waters around Japan. The total global production amounts to 150 – 200,000 tonnes annually. Most krill is used for aquaculture and aquarium feeds, as bait in sport fishing, or in the pharmaceutical industry. In Japan and Russia, krill is also used for human consumption and known as ''okiami'' (オキアミ){{fn|1}} in Japan.

Taxonomy
The order ''Euphausiacea'' is split into two families. The family Bentheuphausiidae has only one species, ''Bentheuphausia amblyops'', a bathypelagic krill living in deep waters below 1,000 m. It is considered the most primitive living species of all krill.{{mn.html">Euphausiidae — contains ten different Genus genera.html" title="Meaning of Brin62}}_The other family — the genera">genera_with a total of 85 species. Of these, the genus ''Euphausia'' is the largest, with 31 species.{{mn|itis|ITIS}} Well-known species—mainly because they are subject to commercial krill fishery—include Antarctic krill (''Euphausia superba''), Pacific krill (''Euphausia pacifica'') and Northern krill (''Meganyctiphanes norvegica''). {{-}}

Distribution
Image:Krill_swarm.jpg right|thumb|300px|A krill swarm Krill occur worldwide in all oceans; most species have transoceanic distribution and several species have endemic (ecology) endemic or neritic restricted distribution. Species of the genus ''Thysanoessa'' occur in both the Atlantic and the Pacific Ocean, which is also home to ''Euphausia pacifica''. Northern krill occurs across the Atlantic, from the north to the Mediterranean Sea. The four species of the genus ''Nyctiphanes'' are highly abundant along the upwelling regions of the California, Humbolt, Benguela, and Canarias Current Systems, where occur most of the largest fisheries activities of fish, molluscs and crustaceans. In the Antarctica Antarctic, seven species are known:{{mn|brueggeman|Bru}} one of the genus ''Thysanoessa'' (''T. macrura'') and six species of the genus ''Euphausia''. The Antarctic krill (''Euphausia superba'') commonly lives at depths up to 100 m,{{mn.html">Ice krill (''Euphausia crystallorophias'') has been recorded at a depth of 4,000 m but commonly lives in depths at most 300 to 600 m deep.{{mn kirkwood|Kir84}} Both are found at latitudes south of 55° S; with ''E. crystallorophias'' dominating south of 74° S{{mn|sala|SAR02}} and in regions of pack ice. Other species known in the Southern Ocean are ''E. frigida'', ''E. longirostris'', ''E. triacantha'', and ''E. vallentini''.{{mn|survey|HFK03}} {{-}}

Morphology
Image:Krillanatomykils.jpg Euphausia superba.html" title="Meaning of right right|thumb|300px|Krill anatomy explained, using ''[[Euphausia superba'' as a model.html" title="Meaning of thumb|300px|Krill anatomy explained, using ''[[Euphausia superba">right|thumb|300px|Krill anatomy explained, using ''[[Euphausia superba'' as a model">thumb|300px|Krill anatomy explained, using ''[[Euphausia superba">right|thumb|300px|Krill anatomy explained, using ''[[Euphausia superba'' as a model Krill are crustaceans and have a chitinous exoskeleton made up of three segments: the cephalon (head), thorax, and the abdomen. The first two segments are fused into one segment, the cephalothorax. This outer shell of krill is transparent in most species. Krill feature intricate compound eyes; some species can adapt to different lighting conditions through the use of screening pigments.{{mn.html">antenna (biology) antennae and several pairs of thoracic legs called pereiopods or thoracopods (so named because they are attached to the thorax; their number varies among genera and species). These thoracic legs include the feeding legs and the grooming legs. Additionally all species have five swimming legs called pleopods or "swimmerets," very similar to those of the common freshwater lobster. Most krill are about 1 to 2 cm long as adults, a few species grow to sizes of the order of 6 to 15 cm. The largest krill species is the mesopelagic ''Thysanopoda spinicauda''.{{mn|brin53|Brin53}} Krill can be easily distinguished from other crustaceans such as true shrimps by their externally visible gills. Image:Euphausia gills.jpg gill.html" title="Meaning of left left|thumb|200px|The [[gills of krill are externally visible..html" title="Meaning of thumb|200px|The [[gill">left|thumb|200px|The [[gills of krill are externally visible.">thumb|200px|The [[gill">left|thumb|200px|The [[gills of krill are externally visible. Many krill are filter feeding filter feeders: their front-most extremities, the thoracopods, form very fine combs with which they can filter out their food from the water. These filters can be very fine indeed in those species (such as ''Euphausia spp.'') that feed primarily on phytoplankton, in particular on diatoms, which are unicellular algae. However, it is believed that all krill species are mostly omnivorous and some few species are carnivorous preying small zooplankton and fish larvae. Except for the ''Bentheuphausia amblyops'' species, krill are Bioluminescence bioluminescent animals having organs called photophores that are able to emit light. The light is generated by an enzyme-catalyzed chemoluminescence reaction, wherein a luciferin (a kind of pigment) is activated by a luciferase enzyme. Studies indicate that the luciferin of many krill species is a fluorescence fluorescent Polypyrrole tetrapyrrole similar but not identical to dinoflagellate luciferin{{mn.html">mating, social interaction or in orientation. Some researchers (e.g. Lindsay & Latz{{mn camouf|LL99}}_or Johnsen{{mn|camouf2|John05}}) have proposed that krill use the light as a form of counter-illumination camouflage to compensate their shadow against the ambient light from above to make themselves more difficult to be seen by predators from below. {{-}}

Behaviour
Most krill are swarming animals; the size and density of such swarms vary greatly depending on the species and the region. Of ''Euphausia superba'', swarms containing up to 10,000 to 30,000 individuals per cubic meter have been reported.{{mn|kils4|KM95}} Swarming is a defensive mechanism, confusing smaller predators that would like to pick out single individuals. Krill typically follow a diel diurnal vertical migration. They spend the day at greater depths and rise during the night towards the surface. The deeper they go, the more they reduce their activity,{{mn|jaffe|JODR99}} apparently to reduce encounters with predators and to conserve energy. Some species (e.g. ''Euphausia superba'', ''E. pacifica'', ''E. hanseni'', ''Pseudeuphausia latifrons'', or ''Thysanoessa spinifera'') also form surface swarms during the day for feeding and reproductive purposes even though such behaviour is dangerous because it makes them extremely vulnerable to predators. Image:Pleopods euphausia superba.jpg pleopod.html" title="Meaning of right right|thumb|200px|Beating [[pleopods of a swimming Antarctic krill..html" title="Meaning of thumb|200px|Beating [[pleopod">right|thumb|200px|Beating [[pleopods of a swimming Antarctic krill.">thumb|200px|Beating [[pleopod">right|thumb|200px|Beating [[pleopods of a swimming Antarctic krill. Dense swarms may elicit a feeding frenzy among predators such as fish or birds, especially near the surface, where escape possibilities for the krill are limited. When disturbed, a swarm scatters, and some individuals have even been observed to molt instantaneously, leaving the exuvia behind as a decoy.{{mn|howard|How05}} Krill normally swim at pace of a few centimetres per second (0.2 – 10 body lengths per second{{mn.html">escape reaction called lobstering: flipping their caudal appendages, i.e. the telson and uropods, they move backwards through the water relatively quickly, achieving speeds in the range of 10 to 27 body lengths per second,{{mn ign|Ign99}} which for large krill such as ''E. superba'' means around 0.8 m/s.{{mn|kils2|Kils82}} Their swimming performance has led many researchers to classify adult krill as nekton|micro-nektonic lifeforms, i.e. small animals capable of individual motion against (weak) currents. Larval forms of krill are generally considered zooplankton.{{mn|nicol|NE97, ch. 2}} {{-}}

Life cycle
Image:Nauplius_Hatching.jpg nauplius (larva) right|thumb|200px|A [[nauplius (larva)|nauplius of ''Euphausia pacifica'' hatching, emerging backwards from the egg..html" title="Meaning of nauplius.html" title="Meaning of right|thumb|200px|A [[nauplius (larva)|nauplius">right|thumb|200px|A [[nauplius (larva)|nauplius of ''Euphausia pacifica'' hatching, emerging backwards from the egg.">nauplius.html" title="Meaning of right|thumb|200px|A [[nauplius (larva)|nauplius">right|thumb|200px|A [[nauplius (larva)|nauplius of ''Euphausia pacifica'' hatching, emerging backwards from the egg. The general life-cycle of krill has been the subject of several studies (e.g. Guerny 1942,{{mn|guerny|Gue42}} or Mauchline & Fisher 1969{{mn|mauchline|MF69}}) performed on a variety of species and is thus relatively well understood, although there are minor variations in details from species to species. When krill hatch from the eggs, they go through several larval stages called the ''nauplius (larva) nauplius'', ''pseudometanauplius'', ''metanauplius'', ''calyptopsis'', and ''furcilia'' stages, each of which is sub-divided into several sub-stages. The pseudometanauplius stage is exclusive of species that lay their eggs within an ovigerous sac (so-called sac-spawners). The larvae grow and ecdysis molt multiple times during this process, shedding their rigid exoskeleton and growing a new one whenever it becomes too small. Smaller animals molt more frequently than larger ones. Until and including the metanauplius stage, the larvae nourish on yolk reserves within their body. Only by the calyptopsis stages, cellular differentiation differentiation has progressed far enough for them to develop a mouth and a digestive tract, and they begin to feed upon phytoplankton. By that time, the larvae must have reached the photic zone, the upper layers of the ocean where algae flourish, for their yolk reserves are exhausted by then and they would starve otherwise. During the furcilia stages, segments with pairs of swimmerets are added, beginning at the frontmost segments. Each new pair becomes functional only at the next molt. The number of segments added during any one of the furcilia stages may vary even within one species depending on environmental conditions.{{mn|knight|Kn84}} After the final furcilia stage, the krill emerges in a shape similar to an adult, but is still immature. During the mating season, which varies depending on the species and the climate, the male deposits a spermatophore sperm package at the genital opening (named ''thelycum'') of the female. The females can carry several thousand eggs in their ovary, which may then account for as much as one third of the animal's body mass.{{mn|ross|RQ86}} Krill can have multiple broods in one season, with interbrood periods of the order of days. Image:Nematoscelis difficilis female.jpg Nematoscelis difficilis.html" title="Meaning of right right|thumb|200px|The head of a female krill of the sac-spawning species ''[[Nematoscelis difficilis'' with her brood sac. The eggs have a diameter of 0.3 – 0.4 Millimetre mm..html" title="Meaning of thumb|200px|The head of a female krill of the sac-spawning species ''[[Nematoscelis difficilis">right|thumb|200px|The head of a female krill of the sac-spawning species ''[[Nematoscelis difficilis'' with her brood sac. The eggs have a diameter of 0.3 – 0.4 Millimetre mm.">thumb|200px|The head of a female krill of the sac-spawning species ''[[Nematoscelis difficilis">right|thumb|200px|The head of a female krill of the sac-spawning species ''[[Nematoscelis difficilis'' with her brood sac. The eggs have a diameter of 0.3 – 0.4 Millimetre mm. There are two types of spawning mechanisms.{{mn|gomez2a|Gom02a}} The 57 species of the genera ''Bentheuphausia'', ''Euphausia'', ''Meganyctiphanes'', ''Thysanoessa'', and ''Thysanopoda'' are "broadcast spawners": the female eventually just releases the fertilized eggs into the water, where they usually sink into deeper waters, disperse, and are on their own. These species generally hatch in the nauplius 1 stage, but recently have been discovered to hatch sometimes as metanauplius or even as calyptopis stages.{{mn|gomez2b|Gom02b}} The remaining 29 species of the other genera are "sac spawners", where the female carries the eggs with her attached to its rearmost pairs of thoracopods until they hatch as metanauplii, although some species like ''Nematoscelis difficilis'' may hatch as nauplius or pseudometanauplius.{{mn|brinton|B+2000}} Some high latitude species of krill can live up to more than six years (e.g. ''Euphausia superba''); others, such as the as mid-latitude species ''Euphausia pacifica'', live only for two years.{{mn|nicol|NE97}} Subtropical or tropical species' longevity is still smaller, like e.g. ''Nyctiphanes simplex'' that usually lives only for six to eight months.{{mn|gomez|Gom05}} Molting occurs whenever the animal outgrows its rigid exoskeleton. Young animals, growing faster, therefore molt more often than older and larger ones. The frequency of molting varies wildly from species to species and is, even within one species, subject to many external factors such as the latitude, the water temperature, or the availability of food. The subtropical species ''Nyctiphanes simplex'', for instance, has an overall intermolt period in the range of two to seven days: larvae molt on the average every three days, while juveniles and adults do so on the average every five days. For ''E. superba'' in the Antarctic sea, intermolt periods ranging between 9 and 28 days depending on the temperature between -1°Celsius C to 4°C have been observed, and for ''Meganyctiphanes norvegica'' in the North Sea the intermolt periods range also from 9 and 28 days but at temperatures between 2.5°C to 15°C.{{mn|buch03|Buch03}} ''E. superba'' is known to be able to reduce its body size when there is not enough food available, molting also when its exoskeleton becomes too large.{{mn|shin|SN02}} Similar shrinkage has also been observed for ''E. pacifica'' (a species occurring in the Pacific Ocean from polar to temperate zones) as an adaptation to abnormally high water temperatures, and has been postulated for other temperate species of krill, too.{{mn|shrink|MM99}} {{-}}

Ecology
Image:Coccolithophore bloom.jpg NASA.html"_title="Meaning of right right|thumb|200px|[[NASA_SeaWiFS satellite image of the large phytoplankton bloom in the Bering Sea in 1998..html" title="Meaning of thumb|200px|[[NASA">right|thumb|200px|[[NASA SeaWiFS satellite image of the large phytoplankton bloom in the Bering Sea in 1998.">thumb|200px|[[NASA">right|thumb|200px|[[NASA SeaWiFS satellite image of the large phytoplankton bloom in the Bering Sea in 1998. Krill are an important element of the food chain. Antarctic krill feed directly on phytoplankton, converting the primary production energy into a form suitable for consumption by larger animals that cannot feed directly on the minuscule algae, but that ''can'' feed upon krill. Some species like the Northern krill have a smaller feeding basket and hunt for copepods and larger zooplankton. Many other animals feed on krill, ranging from smaller animals like fish or penguins to larger ones like pinniped seal and even baleen whales. Disturbances of an ecosystem resulting in a decline of the krill population can have far-reaching effects. During a coccolithophore bloom in the Bering Sea in 1998,{{mn|weier|Wei99}} for instance, the diatom concentration dropped in the affected area. However, krill cannot feed on the smaller coccolithophores, and consequently, the krill population (mainly ''E. pacifica'') in that region declined sharply. This in turn affected other species: the shearwater population dropped, and the incident was even thought to have been a reason for salmon not returning to the rivers of western Alaska in that season.{{mn|brodeur|Br+98}} Other factors besides predators and food availability also can influence the mortality rate in krill populations. There are several single-celled endoparasitoidic ciliates of the genus ''Collinia'' that can infect different species of krill and cause mass dying in affected populations. Such diseases have been reported for ''Thysanoessa inermis'' in the Bering Sea, but also for ''E. pacifica'', ''Thysanoessa spinifera'', and ''T. gregaria'' off the North-American Pacific coast.{{mn|roach|Roa03}} There are also some ectoparasites of the family ''Dajidae'' that afflict krill (and also shrimps and mysids); one such parasite is ''Oculophryxus bicaulis'' which has been found on the krill ''Stylocheiron affine'' and ''S. longicorne''. It attaches itself to the eyestalk of the animal and sucks blood from its head; it is believed that it inhibits the reproduction of its host as none of the afflicted animals found reached maturity.{{mn|dajid|SG96}} See also: Carbon sequestration, biological pump. {{-}}

Economy
''Main article: Krill fishery.'' Image:Krillmeatkils.jpg Antarctic krill.html" title="Meaning of right right|thumb|200px|Deep frozen plates of [[Antarctic krill for use as animal feed and raw material for cooking.html" title="Meaning of thumb|200px|Deep frozen plates of [[Antarctic krill">right|thumb|200px|Deep frozen plates of [[Antarctic krill for use as animal feed and raw material for cooking">thumb|200px|Deep frozen plates of [[Antarctic krill">right|thumb|200px|Deep frozen plates of [[Antarctic krill for use as animal feed and raw material for cooking Krill has been harvested as a food source for both humans (''okiami'') and their domesticated animals since the 19th century, in Japan maybe even earlier. Large-scale fishing developed only in the late 1960s and early 1970s, and now occurs only in Antarctic waters and in the seas around Japan. Historically, the largest krill fishery nations were Japan and the Soviet Union, or, after the latter's dissolution, the Russian Federation and Ukraine. A peak in krill harvest had been reached in 1983 with more than 528,000 tonnes in the Southern Ocean alone (of which the Soviet Union produced 93%). In 1993, two events led to a drastic decline in krill production: first, Russia abandoned its operations, and second, the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) defined maximum catch quotas for a sustainable exploitation of Antarctic krill. Nowadays, the largest krill fishing nations in the Antarctic are Japan, followed by South Korea, Ukraine, and Poland.{{mn|nicol|NE97}} The annual catch in Antarctic waters seems to have stabilized around 100,000 tonnes of krill, which is roughly one fiftieth of the CCAMLR catch quota{{mn|catch|CCAMLR}}. The main limiting factor is probably the high cost associated with Antarctic operations. The fishery around Japan appears to have saturated at some 70'000 tonnes.{{mn|nicol2|NF03}} Experimental small-scale harvesting is being carried out in other areas, too, e.g. fishing for ''Euphausia pacifica'' off British Columbia or harvesting ''Meganyctiphanes norvegica'', ''Thysanoessa raschii'' and ''Thysanoessa inermis'' in the Gulf of St. Lawrence. These experimental operations produce only a few hundred tonnes of krill per year. Nicol & Foster{{mn|nicol2|NF03}} consider it unlikely that any new large-scale harvesting operations in these areas will be started due to the opposition from local fishing industries and conservation groups. Krill taste salty and somewhat stronger than shrimp. For mass-consumption and commercially prepared products, they must be peeled because their exoskeleton contains fluorides, which are toxic in high concentrations.{{mn|haberman|Hab97}} Excessive intake of ''okiami'' may cause diarrhea. {{-}}

Footnotes
{{fnb|1}} The scientific name ''Euphausiacea'' is ''okiamime'' (オキアミ目) in [http://www.oceandictionary.net/lae.html Japanese].

References
The referencing system used in this article follows the ''alpha.bst'' style of BibTeX. *{{mnb2|brin53|Brin53}} Brinton, E.: Thysanopoda spinicauda'', a new bathypelagic giant euphausiid crustacean, with comparative notes on'' T. cornuta ''and'' T. egregia. J. Wash. Acad. Sci. 43, pp. 408 – 412; 1953. *{{mnb2|brin62|Brin62}} Brinton, E.: ''The distribution of Pacific euphausiids.'', Bull. Scripps Inst. Oceanogr. '''8'''(2), pp. 51 – 270; 1962. *{{mnb2|brinton|B+2000}} Brinton, E.; Ohman, M. D.; Townsend, A. W.; Knight, M. D.; Bridgeman, A. L.: ''[http://www.springeronline.com/sgw/cda/frontpage/0,10735,1-10038-22-1578932-0,00.html Euphausiids of the World Ocean]'', World Biodiversity Database CD-ROM Series; Springer Verlag, 2000. ISBN 3-540-14673-3. *{{mnb2|brodeur|Br+98}} Brodeur, R.D.; Kruse, G.H.; ''et al.'': ''Draft Report of the FOCI International Workshop on Recent Conditions in the Bering Sea'', pp. 22 – 26; NOAA 1998. *{{mnb2|brueggeman|Bru}} Brueggeman, P.: ''[http://scilib.ucsd.edu/sio/nsf/fguide/arthropoda10.html Euphausia crystallorophias]'', from the [http://scilib.ucsd.edu/sio/nsf/fguide/ Underwater Field Guide to Ross Island & McMurdo Sound, Antarctica]. *{{mnb2|buch03|Buch03}} Buchholz, F.: [http://taylorandfrancis.metapress.com/link.asp?id=w7capjjptvm7ebtx ''Experiments on the physiology of Southern and Northern krill, ''Euphausia superba'' and ''Meganyctiphanes norvegica'', with emphasis on moult and growth – a review''], Marine and Freshwater Behaviour and Physiology '''36'''(4), pp. 229 – 247, 2003. *{{mnb2|catch|CCAMLR}} CCAMLR: [http://www.ccamlr.org/pu/E/sc/fish-monit/hs-krill.htm ''Harvested species: Krill (''Eupausia superba'')'']. Accessed June 20, 2005. *{{mnb2|luciferin2|DHS80}} Dunlap J. C.; Hastings, J. W.; Shimomura, O.: ''[http://www.pnas.org/cgi/reprint/77/3/1394 Crossreactivity between the Light-Emitting Systems of Distantly Related Organisms: Novel Type of Light-Emitting Compound]'', Proc. Natl. Acad. Sci. USA, '''77'''(3), pp. 1394&nbasp;– 1397, March 1980. *{{mnb2|gaten|Gat05}} Gaten, E.: [http://www.le.ac.uk/biology/gat/krill.html ''Meganyctiphanes norvegica'']; accessed Jun 15, 2005. *{{mnb2|gomez2a|Gom02a}} Gómez-Gutiérrez, J.: [http://www.rain.org/pipermail/sanctuary-naturalist-corps/2002-August/000839.html ''Personal communication'']; 2002. *{{mnb2|gomez2b|Gom02b}} Gómez-Gutiérrez, J.: ''[http://reo.nii.ac.jp/journal/HtmlIndicate/Contents/SUP0000003000/JOU0003000131/ISS0000015774/ART0000182425/ART0000182425.pdf Hatching mechanism and delayed hatching of the eggs of three broadcast spawning euphausiid species under laboratory conditions]'', J. of Plankton Research '''24'''(12), pp. 1265 – 1276, 2002. Has many images of the earliest development stages of krill. *{{mnb2|gomez|Gom05}} Gómez-Gutiérrez, J.: [http://www.geocities.com/jgomez64/euphausiids.html Euphausiids]; accessed Jun 16, 2005. *{{mnb2|guerny|Gue42}} Gurney, R.: ''Larvae of decapod crustacea.'' Royal Society Publ. 129; London 1942. *{{mnb2|haberman|Hab97}} Haberman, K: ''[http://quest.arc.nasa.gov/antarctica2/ask/new/Miscellaneous_questions_about_krill.txt Answers to miscellaneous questions about krill]'', February 26, 1997. Accessed June 17, 2005. *{{mnb2|howard|How05}} Howard, D.: ''[http://oceanexplorer.noaa.gov/explorations/02quest/background/krill/krill.html Krill in Cordell Bank National Marine Sanctuary]'', NOAA. Last accessed June 15, 2005. *{{mnb2|survey|HFK03}} Hosie, G. W.; Fukuchi, M.; Kawaguchi, S.: ''[http://192.171.163.165/PDF_files/symposium%20manuscripts/PIO%2058%20Hosie%20263-283.pdf Development of the Southern Ocean Continuous Plankton Recorder survey]'', Progress in Oceanography 58, pp. 263 – 283, 2003. *{{mnb2|rotate_photo|HW01}} Herring, P. J.; Widder, E. A.: ''[http://www.isbc.unibo.it/Files/BC_PlanktonNekton.htm Bioluminescence in Plankton and Nekton]''; in Steele, J. H., Thorpe, S. A.; Turekian, K. K. (eds.): ''Encyclopedia of Ocean Science'', Vol. 1, pp. 308 – 317. Academic Press, San Diego, 2001. *{{mnb2|ign|Ign99}} Ignatyev, S. M.: ''[http://www.ibss.iuf.net/people/ignat/ikrill99.html Functional-Morphological Adaptations of the Krill to Active Swimming]'', Poster on the 2^nd International Symposium on Krill, Santa Cruz, California, USA; August 23-27, 1999. *{{mnb2|itis|ITIS}} [http://www.itis.usda.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=95496 Taxonomy of ''Euphausiacea''] from ITIS. *{{mnb2|jaffe|JODR99}} Jaffe, J.S.; Ohmann, M. D.; De Robertis, A.: [http://jaffeweb.ucsd.edu/pubs/Sonar%20estimates%20of%20daytime%20activity%20levels%20of%20Euphausia%20pacifica%20in%20Saanich%20Inlet.pdf ''Sonar estimates of daytime activity levels of ''Euphausia pacifica'' in Saanich Inlet''], Can. J. Fish. Aquat. Sci. '''56''', pp. 2000 – 2010; 1999. *{{mnb2|camouf2|John05}} Johnsen, S.: ''[http://www.biology.duke.edu/johnsenlab/pdfs/pubs/blcolor.pdf The Red and the Black: Bioluminescence and the Color of Animals in the Deep Sea]'', Integr. Comp. Biol. 45, pp. 234 – 246, 2005. *{{mnb2|kils2|Kils82}} 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. *{{mnb2|kils4|KM95}} 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. *{{mnb2|kirkwood|Kir84}} Kirkwood, J.A.: ''A Guide to the ''Euphausiacea'' of the Southern Ocean.'' Australian National Antarctic Research Expedition; Australia Dept of Science and Technology, Antarctic Division; 1984. *{{mnb2|knight|Kn84}} Knight, M. D.: [http://www.calcofi.org/newhome/publications/CalCOFI_Reports/v25/pdfs/Vol_25_Knight.pdf ''Variation in Larval Morphogenesis within the Southern California Bight Population of ''Euphausia pacifica'' from Winter through Summer, 1977-1978''], CalCOFI Report Vol. XXV, 1984. *{{mnb2|camouf|LL99}} Lindsay, S. M.; Latz, M. I.: ''[http://aslo.org/meetings/santafe99/abstracts/SS16TH1326S.html Experimental Evidence for Luminescent Countershading by some Euphausiid Crustaceans]'', Poster presented at the American Society of Limnology and Oceanography (ASLO) Aquatic Sciences Meeting, Santa Fe, 1999. *{{mnb2|marinebio|MarineBio}} [http://marinebio.org/species.asp?id=518 Krill] at MarineBio. *{{mnb2|mauchline|MF69}} Mauchline, J.; Fisher, L.R.: ''The biology of euphausiids.'' Adv. Mar. Biol. 7; 1969. *{{mnb2|shrink|MM99}} Marinovic, B.; Mangel, M.: ''[http://people.ucsc.edu/~msmangel/MM.pdf Krill can shrink as an ecological adaptation to temporarily unfavourable environments]'', Ecology Letters 2, pp. 338 – 343; Blackwell Science, 1999. *{{mnb2|nicol|NE97}} 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. *{{mnb2|nicol2|NF03}} 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. *{{mnb2|roach|Roa03}} Roach, J.: ''[http://news.nationalgeographic.com/news/2003/07/0717_030717_krillkiller.html Scientists Discover Mystery Krill Killer]'', National Geographic News, July 17, 2003. See also the base article: Gómez-Gutiérrez, J.; Peterson, W. T.; De Robertis, A.; Brodeur, R. D.: ''Mass Mortality of Krill Caused by Parasitoid Ciliates,'' Science (journal) Science Vol 301; issue 5631, pp. 339f; July 18, 2003. *{{mnb2|ross|RQ86}} Ross, R. M.; Quetin, L. B.: ''How Productive are Antarctic Krill?'' Bioscience 36, pp. 264 – 269; 1986. *{{mnb2|sala|SAR02}} Sala, A.; Azzali, M.; Russo, A.: [http://www.icm.csic.es/scimar/662sal.html ''Krill of the Ross Sea: distribution, abundance and demography of ''Euphausia superba'' and ''Euphausia crystallorophias'' during the Italian Antarctic Expedition (January-February 2000)''], Scientia Marina '''66'''(2), pp. 123 – 133. 2002. *{{mnb2|dajid|SG96}} Shields, J.D.; Gómez-Gutiérrez, J.: [http://www.geocities.com/CollegePark/Grounds/6882/dajidae.html Oculophryxus bicaulis'', a new genus and species of dajid isopod parasitic on the euphausiid ''Stylocheiron affine'' Hansen''], Int'l J. for Parasitology '''26'''(3), pp. 261 – 268; 1996. *{{mnb2|luciferin1|Shi95}} Shimomura, O.: ''[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7676855&dopt=Abstract The roles of the two highly unstable components F and P involved in the bioluminescence of euphausiid shrimps]'', Jour. Biolumin. Chemilumin. '''10'''(2), pp. 91 – 101, 1995. *{{mnb2|shin|SN02}} Hyoung-Chul Shin; Nicol, S.: [http://www.int-res.com/abstracts/meps/v239/p157-167/ ''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. *{{mnb2|weier|Wei99}} Weier, J.: ''[http://earthobservatory.nasa.gov/Study/Coccoliths/bering_sea.html Changing Currents color the Bering Sea a new shade of Blue]'', NOAA Earth Observatory, 1999. Last accessed June 15, 2005.

Further reading
{{Commons|Krill}} {{Wikispecies|Euphausia}} {{wiktionary}} *Boden, Brian P.; Johnson, Martin W. Johnson; Brinton, Edward: [http://repositories.cdlib.org/sio/bulletin/6no8/ Euphausiacea (Crustacea) of the North Pacific.] Bulletin of the Scripps Institution of Oceanography. Volume 6 Number 8, 1955. *Brinton, Edward: [http://repositories.cdlib.org/sio/bulletin/8no2/ The distribution of Pacific euphausiids]. Bulletin of the Scripps Institution of Oceanography, Volume 8, no. 2, pages 51-269. 1962. *Brinton, Edward: [http://repositories.cdlib.org/sio/naga/4pt5/ Euphausiids of Southeast Asian waters.] Naga Report volume 4, part 5. La Jolla : University of California, Scripps Institution of Oceanography, 1975. *Conway, D. V. P.; White, R. G.; Hugues-Dit-Ciles, J.; Galienne, C. P.; Robins, D. B.: ''[http://www.pml.ac.uk/pml/sharing/zooplankton.htm Guide to the coastal and surface zooplankton of the South-Western Indian Ocean]'', [http://www.pml.ac.uk/pml/sharing/Darwin%20Guide/section%2013.pdf ''Order'' Euphausiacea], Occasional Publication of the Marine Biological Association of the United Kingdom No. 15, Plymouth, UK, 2003. *Everson, I. (ed.): ''Krill: biology, ecology and fisheries.'' Oxford, Blackwell Science; 2000. ISBN 0-632-05565-0. *Mauchline, J.: [http://www.ices.dk/products/fiche/Plankton/SHEET134.PDF Euphausiacea: ''Adults''], Conseil International pour l'Exploration de la Mer, 1971. Identification sheets for adult krill with many line drawings. PDF file, 2 Megabyte Mb. *Mauchline, J.: [http://www.ices.dk/products/fiche/Plankton/SHEET135-137.PDF Euphausiacea: ''Larvae''], Conseil International pour l'Exploration de la Mer, 1971. Identification sheets for larval stages of krill with many line drawings. PDF file, 3 Mb. *Tett, P.: ''[http://www.lifesciences.napier.ac.uk/teaching/MB/Euphausiid03.html The biology of Euphausiids]'', lecture notes from a [http://www.lifesciences.napier.ac.uk/teaching/MB/Index.html 2003 course in Marine Biology] from Napier University. Last accessed July 18, 2005. *Tett, P.: ''[http://www.lifesciences.napier.ac.uk/teaching/MB/MB9.html Bioluminescence]'', lecture notes from the 1999/2000 edition of that same course. Last accessed July 18, 2005. {{featured article}} Category:Krill ca:Krill da:Krill de:Krill es:Krill eo:Krilo fr:Krill it:Krill nl:Krill ja:オキアミ no:Krill pl:Kryl antarktyczny pt:Krill ru:Криль sv:Lysräkor {{sisterlinkswp|Category:Euphausiacea}} '''Krill''' are crustaceans of the Order (biology) order '''Euphausiacea'''. {{catmore}} Category:Crustaceans

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