Крил

Euphausiacea
Антарктички крил (Meganyctiphanes norvegica)
Научна класификација
Царство:	Animalia
Тип:	Arthropoda
Подтип:	Crustacea
Класа:	Malacostraca
Надред:	Eucarida
Ред:	Euphausiacea Dana, 1852
Породице и родови
Euphausiidae Euphausia Dana, 1852 Meganyctiphanes Holt and W. M. Tattersall, 1905 Nematobrachion Calman, 1905 Nematoscelis G. O. Sars, 1883 Nyctiphanes G. O. Sars, 1883 Pseudeuphausia Hansen, 1910 Stylocheiron G. O. Sars, 1883 Tessarabrachion Hansen, 1911 Thysanoessa Brandt, 1851 Thysanopoda Latreille, 1831 Bentheuphausiidae Bentheuphausia G. O. Sars, 1885

Антарктички крил

Крил је норвешка реч која дословно преведена значи „храна китова“. У ужем смислу крил означава мале раколике животињице, планктон (тачније зоопланктон) из реда Euphausiacea.

Krill are considered an important trophic level connection – near the bottom of the food chain. They feed on phytoplankton and (to a lesser extent) zooplankton, yet also are the main source of food for many larger animals. In the Southern Ocean, one species, the Antarctic krill, Euphausia superba, makes up an estimated biomass of around 379,000,000 tonnes, making it among the species with the largest total biomass. Over half of this biomass is eaten by Whales, seals, Penguins, squid, and fish each year. Most krill species display large daily vertical migrations, thus providing food for predators near the surface at night and in deeper waters during the day.

Опис врсте

Најпознатија врста је антарктички крил (Euphausia superba). Појављује се у дивовским јатима. Његова биомаса се процењује на 100—800 милиона тона. Поређења ради, укупна количина излова рибе на свету износи око 100 милиона тона.

Крил представља основу целог екосистема Антарктика. Главни је извор хране за китове, фоке, пингвине, лигње, албатросе и друге птице. Може да нарасте до дужине од 6 центиметара и тежине од 2 грама. Претпоставља се да може да живи око 6 година. Кожа му је прозирна, па се назире зелени „желудац“. То је знак да се храни претежно фитопланктоном, и то углавном силикатним алгама које филтрира из воде фасцинантним корпицама за лов.

Крил такође може да жање фитопланктон директно са доње стране ледених санти. На очима има органе који светлуцају жутозелено светло (биолуминисценција), па га зато зову и светлуцави рачић.

Таксономија

Krill belong to the large arthropod subphylum, the Crustacea. The most familiar and largest group of crustaceans, the class Malacostraca, includes the superorder Eucarida comprising the three orders, Euphausiacea (krill), Decapoda (shrimp, prawns, lobsters, crabs), and the planktonic Amphionidacea.

The order Euphausiacea comprises two families. The more abundant Euphausiidae contains 10 different genera with a total of 85 species. Of these, the genus Euphausia is the largest, with 31 species. The lesser known family, the Bentheuphausiidae, has only one species, Bentheuphausia amblyops, a bathypelagic krill living in deep waters below 1.000 m (3.300 ft). It is considered the most primitive extant krill species.

Well-known species of the Euphausiidae of commercial krill fisheries include Antarctic krill (Euphausia superba), Pacific krill (E. pacifica) and Northern krill (Meganyctiphanes norvegica).

Филогенија

Предложена филогенија реда Euphausiacea

Euphausiacea Bentheuphausiidae Bentheuphausia   Euphausiidae   Thysanopoda (♣)     Nematobrachion (♦)   Euphausiinae   Meganyctiphanes   Euphausiini (♠)(♦)   Pseudeuphausia     Euphausia     Nematoscelini (♠)   Nyctiphanes   Nematoscelina (♠)   Nematoscelis     Thysanoessa     Tessarabrachion     Stylocheiron

Филогенија добијена из морфолошких података, (♠) skovana имена, (♣) вероватно парафилетски таксон због Nematobrachion, (♦) кладе се разликују од Казанове (1984), где је Pseudoeuphausia сестра Nyctiphanes, Euphausia је сестра Thysanopoda, a Nematobrachion је сестра Stylocheiron.

Према подацима из 2013. године, the order Euphausiacea is believed to be monophyletic due to several unique conserved morphological characteristics (autapomorphy) such as its naked filamentous gills and thin thoracopods and by molecular studies.

There have been many theories of the location of the order Euphausiacea. Since the first description of Thysanopode tricuspide by Henri Milne-Edwards in 1830, the similarity of their biramous thoracopods had led zoologists to group euphausiids and Mysidacea in the order Schizopoda, which was split by Johan Erik Vesti Boas in 1883 into two separate orders. Later, William Thomas Calman (1904) ranked the Mysidacea in the superorder Peracarida and euphausiids in the superorder Eucarida, although even up to the 1930s the order Schizopoda was advocated. It was later also proposed that order Euphausiacea should be grouped with the Penaeidae (family of prawns) in the Decapoda based on developmental similarities, as noted by Robert Gurney and Isabella Gordon. The reason for this debate is that krill share some morphological features of decapods and others of mysids.

Molecular studies have not unambiguously grouped them, possibly due to the paucity of key rare species such as Bentheuphausia amblyops in krill and Amphionides reynaudii in Eucarida. One study supports the monophyly of Eucarida (with basal Mysida), another groups Euphausiacea with Mysida (the Schizopoda), while yet another groups Euphausiacea with Hoplocarida.

Врсте

• Bentheuphausia amblyops (G. O. Sars, 1883)
• Euphausia americana Hansen, 1911
• Euphausia brevis Hansen, 1905
• Euphausia crystallorophias Holt and Tattersall, 1906
• Euphausia diomedeae Ortmann, 1894
• Euphausia distinguenda Hansen, 1908
• Euphausia eximia Hansen, 1911
• Euphausia fallax Hansen, 1916
• Euphausia frigida Hansen, 1911
• Euphausia gibba G. O. Sars, 1883
• Euphausia gibboides Ortmann, 1893
• Euphausia hanseni Zimmer, 1915
• Euphausia hemigibba Hansen, 1910
• Euphausia krohnii (Brandt, 1851)
• Euphausia lamelligera Hansen, 1911
• Euphausia longirostris Hansen, 1908
• Euphausia lucens Hansen, 1905
• Euphausia mucronata G. O. Sars, 1883
• Euphausia mutica Hansen, 1905
• Euphausia nana Brinton, 1962
• Euphausia pacifica Hansen, 1911
• Euphausia paragibba Hansen, 1910
• Euphausia pseudogibba Ortmann, 1893
• Euphausia recurva Hansen, 1905
• Euphausia sanzoi Torelli, 1934
• Euphausia sibogae Hansen, 1908
• Euphausia similis G. O. Sars, 1885
• Euphausia spinifera G. O. Sars, 1885
• Euphausia superba Dana, 1852
• Euphausia tenera Hansen, 1905
• Euphausia triacantha Holt and Tattersall, 1906
• Euphausia vallentini Stebbing, 1900
• Meganyctiphanes norvegica (M. Sars, 1857)
• Nematobrachion boopis (Calman, 1896)
• Nematobrachion flexipes (Ortmann, 1893)
• Nematobrachion sexspinosus Hansen, 1911
• Nematoscelis atlantica Hansen, 1910
• Nematoscelis difficilis Hansen, 1911
• Nematoscelis gracilis Hansen, 1910
• Nematoscelis lobata Hansen, 1916
• Nematoscelis megalops G. O. Sars, 1883
• Nematoscelis microps G. O. Sars, 1883
• Nematoscelis tenella G. O. Sars, 1883
• Nyctiphanes australis G. O. Sars, 1883
• Nyctiphanes capensis Hansen, 1911
• Nyctiphanes couchii (Bell, 1853)
• Nyctiphanes simplex Hansen, 1911
• Pseudeuphausia latifrons (G. O. Sars, 1883)
• Pseudeuphausia sinica Wang and Chen, 1963
• Stylocheiron abbreviatum G. O. Sars, 1883
• Stylocheiron affine Hansen, 1910
• Stylocheiron armatum Colosi, 1917
• Stylocheiron carinatum G. O. Sars, 1883
• Stylocheiron elongatum G. O. Sars, 1883
• Stylocheiron indicus Silas and Mathew, 1967
• Stylocheiron insulare Hansen, 1910
• Stylocheiron longicorne G. O. Sars, 1883
• Stylocheiron maximum Hansen, 1908
• Stylocheiron microphthalma Hansen, 1910
• Stylocheiron robustum Brinton, 1962
• Stylocheiron suhmii G. O. Sars, 1883
• Tessarabrachion oculatus Hansen, 1911
• Thysanoessa gregaria G. O. Sars, 1885
• Thysanoessa inermis (Krøyer, 1846)
• Thysanoessa inspinata Nemoto, 1963
• Thysanoessa longicaudata (Krøyer, 1846)
• Thysanoessa longipes Brandt, 1851
• Thysanoessa macrura G. O. Sars, 1885
• Thysanoessa parva Hansen, 1905
• Thysanoessa raschii (M. Sars, 1864)
• Thysanoessa spinifera Holmes, 1900
• Thysanoessa vicina Hansen, 1911
• Thysanopoda acutifrons Holt and W. M. Tattersall, 1905
• Thysanopoda aequalis Hansen, 1905
• Thysanopoda astylata Brinton, 1975
• Thysanopoda cornuta Illig, 1905
• Thysanopoda cristata G. O. Sars, 1883
• Thysanopoda egregia Hansen, 1905
• Thysanopoda microphthalma G. O. Sars, 1885
• Thysanopoda minyops Brinton, 1987
• Thysanopoda monacantha Ortmann, 1893
• Thysanopoda obtusifrons G. O. Sars, 1883
• Thysanopoda orientalis Hansen, 1910
• Thysanopoda pectinata Ortmann, 1893
• Thysanopoda spinicaudata Brinton, 1953
• Thysanopoda tricuspida H. Milne Edwards, 1837

Литература

• Boden, Brian P.; Martin W. Johnson; Brinton, Edward: Euphausiacea (Crustacea) of the North Pacific. Bulletin of the Scripps Institution of Oceanography. Volume 6 Number 8, 1955.
• Edward Brinton: 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.: Guide to the coastal and surface zooplankton of the South-Western Indian Ocean, 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 978-0-632-05565-4.
• Mauchline, J.: Euphausiacea: Adults, Conseil International pour l'Exploration de la Mer, 1971. Identification sheets for adult krill with many line drawings. PDF file, 2 Mb.
• Mauchline, J.: 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.: The biology of Euphausiids, lecture notes from a 2003 course in Marine Biology from Napier University.
• Tett, P.: Bioluminescence, lecture notes from the 1999/2000 edition of that same course.

Спољашње везе

• Webcam of Krill Aquarium at Australian Antarctic Division
• 'Antarctic Energies' animation by Lisa Roberts