等足目

等足目（學名：Isopoda），又名等足類或等腳類，是一目甲殼類，其下包括了潮蟲及球潮蟲。等足目的化石紀錄可以追溯至3億年前的石炭紀。 其學名是來自希臘文的「相等」及「腳」，故中文名等足目。 等足目是體型較細小的甲殼類，有七對大小及形態相似的腳，體型由300微米至50厘米不等。它們的腹背一般都是扁平的，但在深海或地下水中的物種很多時都會不同。等足目沒有明顯的甲殼，只在頭部有殼。氣體交換是由似鰓的腹肢開始至身體後部。陸地生活的等足目很多時都有像肺部的結構，往往在底部顯而易見。若有眼睛，都是無柄的。與異足目一樣，它們最後的腹節與尾節融合，組成腹尾節。胸部的第一節則與頭部融合。胸部附器是單枝的，而腹肢則是二枝的。 約有4500種等足目是生活在水中的，大部份分佈在海床。約有500種是淡水的，其餘5000種是屬於潮蟲亞目，遠比陸生的其他甲殼類成功。在深海中以櫛水虱亞目較為豐富，差不多完全排除了其他等足目，成功發展輻射適應。 一些等足目發展成寄生生態。上蝦亞目是完全寄生的，而扇肢亞目則是部份寄生。例如縮頭魚虱（Cymothoa exigua）是寄生在墨西哥笛鯛中，它會吃了墨西哥笛鯛的舌頭，並且取而代之，是已知唯一在功能上取代主體的寄生方式。 等足目屬於囊蝦總目，有特製的育幼袋孵蛋。根據2001年的分類，當時約有11437個物種，分別分類在11個亞目。 Acanthaspidiidae Ianthopsis Beddard, 1886 Iolanthe Beddard, 1886 Mexicope Hooker, 1985 Mexicope kensleyi Hooker, 1985 Mexicope maletensis Riehl & Schienbein, 2024 Mexicope sushara Bruce, 2004 Mexicope westralia Just, 2001 纺锤水虱科 Aegidae Agnaridae Alloniscidae Amphisopidae Amphisopodidae Ancinidae Antarcturidae Abyssarcturus Kussakin & Vasina, 1995 Acantharcturus Schultz, 1981 Antarcturus Caecarcturus Schultz, 1981 Chaetarcturus Brandt, 1990 Cylindrarcturus Schultz, 1981 Fissarcturus Bathyweddellensis, 2007 Fissarcturus Brandt, 1990 Fissarcturus Rossi, 2007 Fissarcturus Sandwichi, 2007 Furcarcturus Baltzer, Held & Wägele, 2000 Glaberarcturus Kussakin & Vasina, 1998 Globarcturus Kussakin & Vasina, 1994 Halearcturus Poore, 2015 Litarcturus Brandt, 1990 Marmachius Poore, 2012 Mixarcturus Brandt, 1990 Oxyarcturus Brandt, 1990 Tuberarcturus Brandt, 1990 Xiphoarcturus Pereira, Roccatagliata & Doti, 2019 背尾水虱科 Antheluridae Anthuridae Anuropidae Archaeoniscidae Archeoniscidae Arcturidae Arcturididae Armadillidae 球木虱科 Armadillidiidae Armadilliidae Asconiscidae 栉水虱科 Asellidae Atlantasellidae Atlantidiidae 澳洲水虱科 Austrarcturellidae Balloniscidae Barybrotidae Basserolidae 异深水虱科 Bathynataliidae Bathynomidae Bathytropidae Berytoniscidae Bisilvestriidae 鳃虱科 Bopyridae Brasileirinidae Buddelundiellidae Cabiropidae 大尾水虱科 Calabozoidae Capitoniscidae Chaetilidae Chaetiliidae 漂水虱科 Cirolanidae 珊瑚水虱科 Corallanidae Crinoniscidae Cryptoniscidae Cryptothiridae Cumoechidae Cylisticidae 缩头鱼虱科 Cymothoidae Cyproniscidae Dajidae Delatorreiidae Dendrotionidae Desmosomatidae Detonidae Dubioniscidae Echinothambematidae 内虱科 Entoniscidae Entophilidae Eubelidae Excorallanidae ，为Corallanidae的异名 Expanathuridae Gnathidae 巨颚水虱科 Gnathiidae Gnathostenetroididae Hadromastacidae Halophilosciidae Haplomunnidae Haploniscidae Hekelidae Hemioniscidae Holidoteidae Holognathidae Hypsimetopidae Hyssuridae Idoteidae Ionidae Irmaosidae Ischnomesidae 寄藻水虱科 Janirellidae Janiridae Joeropsididae Katianiridae Keuphyliidae Lantoceramiidae Lepidocharontidae Leptanthuridae 海蟑螂科 Ligiidae Limnoriidae Macrostylidae Mesamphisopidae Mesoniscidae Mesosignidae 小角水虱科 Microcerberidae Microniscidae Microparasellidae Mictosomatidae 浮游水虱科 Munnidae Munnopsidae Nannoniscidae Olibrinidae 海蛆科 Oniscidae Diacara Budde-Lund, 1908 Exalloniscus Stebbing, 1911 Exalloniscus albus (Dollfus, 1898) Exalloniscus beroni Taiti & Ferrara, 1988 Exalloniscus bicoloratus Taiti & Ferrara, 1988 Exalloniscus borneanus Taiti & Ferrara, 1988 Exalloniscus brincki Manicastri & Argano, 1986 Exalloniscus burmaensis Taiti & Cardoso, 2020 Exalloniscus caudatus Taiti & Ferrara, 1988 Exalloniscus coecus (Dollfus, 1898) Exalloniscus convexus Taiti & Cardoso, 2020 Exalloniscus cortii Arcangeli, 1927 Exalloniscus curvispinatus Li & Jiang, 2024 Exalloniscus deharvengi Taiti & Cardoso, 2020 Exalloniscus duospinatus Li & Jiang, 2024 Exalloniscus japonicus Taiti & Gruber, 2008 Exalloniscus kampucheaensis Taiti & Cardoso, 2020 Exalloniscus malaccensis Taiti & Ferrara, 1988 Exalloniscus maschwitzi Taiti & Ferrara, 1988 Exalloniscus nepalensis Schmalfuss, 1983 Exalloniscus papillosus (Budde-Lund, 1912) Exalloniscus rotundatus Taiti & Ferrara, 1986 Exalloniscus schmalfussi Taiti & Cardoso, 2020 Exalloniscus siamensis Taiti & Cardoso, 2020 Exalloniscus silvestrii Kwon & Taiti, 1993 Exalloniscus stilifer Taiti & Cardoso, 2020 Exalloniscus sumatranus Manicastri & Taiti, 1991 Exalloniscus taitii Li & Jiang, 2024 Exalloniscus thailandensis Dalens, 1987 Exalloniscus tortilis Taiti & Cardoso, 2020 Exalloniscus triangulus Li & Jiang, 2024 Exalloniscus tridentatus Li & Jiang, 2024 Exalloniscus troglophilus Taiti & Gruber, 2008 Exalloniscus tuberculatus Nunomura, 2000 Exalloniscus vietnamensis Taiti & Ferrara, 1988 Hanoniscus Budde-Lund, 1912 Hiatoniscus Barnard, 1932 Hora Barnard, 1932 Krantzia Barnard, 1932 海蛆属 Oniscus Linnaeus, 1758 Oroniscus Verhoeff, 1908 Phalloniscus Budde-Lund, 1908 Rabdoniscus Vandel, 1981 Rodoniscus Arcangeli, 1934 Sardoniscus Arcangeli, 1939 Tasmanoniscus Vandel, 1973 Palaeophreatoicidae Paramunnidae Paranthuridae Paraplatyarthridae Parasellidae Periscyphicidae Philosciidae Phoratopodidae 坑水虱科 Phreatoicidae Phreatoicopsidae Phreatoicopsididae Plakarthriidae 蚁虱科 Platyarthridae Pleurocopidae Podasconidae Ponderellidae 鼠妇科 Porcellionidae Protognathiidae Protojaniridae Pseudarmadillidae Pseudidotheidae Pseudojaniridae Pudeoniscidae Rectarcturidae Rhyscotidae Santiidae Schoebliidae Schweglerellidae Scleropactidae Scyphacidae 扁水虱科 Serolidae Spelaeoniscidae 团水虱科 Sphaeromatidae Sphaeroniscidae Stellatoniscidae Stenasellidae Stenetriidae Stenoniscidae Styloniscidae Tainisopidae Tecticipitidae Tendosphaeridae Thambematidae Thermoarcturidae Titanidae Trachelipodidae Tricarinidae 毛潮虫科 Trichoniscidae Tridentellidae Turanoniscidae 瘤水虱科 Tylidae Urdidae Urstylidae Vermectiadidae Xenarcturidae Xenosellidae 科的地位未定的属： Anhelkocephalon Bill, 1914 Arctasellus Henry & Magniez, 1995 Austrorgathona Brunnella Polz, 2005 Chimaeroniscus Williams, Boyko & Moritaki, 2022 Congloboniscus Jackson, 1938 Crenisopus Wilson & Keable, 1999 Cryptocotitus Schultz, 1977 Cryptolacruma Schädel, Hörnig, Hyžný & Haug, 2021 Cylisticoides Schmalfuss, 2003 Debodea Hiller, 1999 Discosalaputium Schädel, van Eldijk, Winkelhorst, Reumer & Haug, 2020 Electrolana Schädel, Hyžný & Haug, 2021 Elocryptus Schultz, 1977 Ennurensis Collinge, 1915 Eoarmadillidium Dollfus, 1904 Eobooralana Schädel, Nagler & Hyžný, 2023 Gelrincola Schädel, van Eldijk, Winkelhorst, Reumer & Haug, 2020 Helleria Czerniavsky, 1868 Jaerella Richardson, 1911 Kanthyloma Klompmaker, Artal, van Bakel, Fraaije & Jagt, 2014 Leptaspidia Bate & Westwood, 1868 Mauritaniscus Vandel, 1958 Musconiscus Arcangeli, 1930 Nalocryptus Schultz, 1977 Nococryptus Schultz, 1977 Olincera W.E.Leach Oniscomorphus Jackson, 1938 Onocryptus Schultz, 1977 Osicryptus Schultz, 1977 Ourachaerus Kinahan, 1859 Paraleptotrichus Arcangeli, 1927 Philoscodillo Jackson, 1938 Platuropodus Pazinato, Haug, Rohn, Adami-Rodrigues, Pirani Ghilardi, Cardoso Langer & Haug, 2021 Platyburmoniscus Schmidt, 2000 Potrerillo de Armas & Juarrero de Varona, 1999 Pseudodiploexochus Taiti, Paoli & Ferrara, 1998 Reboursia Guinot, Wilson & Schram, 2005 Rhacura Richardson, 1908 Rotungus Collinge, 1916 Squilloides Tchindono & Tchesun, 1993 Strigoproavus Schollmann, 1993 Synuropus Richardson, 1901 Thermaloniscus Bourdon, 1983 Tole Ortmann, 1901 Trichopleon Beddard, 1886 Trisopodoniscus Bourdon, 1981 Unusuropode Duarte & Santos, 1962 Urias Richardson, 1911 Vacuotheca Schädel, Perrichot & Haug, 2019 Xostylus Menzies, 1962 等足目的幼蟲如同其成蟲，但卻沒有最後一對胸足。等足目生長周期中沒有了游泳階段是限制其分佈的原因，並形成高度特有性。它們會以兩個階段來脫殼。 Boxshall, Geoff. Isopoda. WoRMS. 2014 [2014-05-08].  Dreyer, Hermann; Wägele, Johann-Wolfgang. The Scutocoxifera Tax. Nov. and the Information Content of Nuclear ssu rDNA Sequences for Reconstruction of Isopod Phylogeny (Peracarida: Isopoda). Journal of Crustacean Biology. 2002-05, 22 (2): pp. 217–234 [2017-07-17]. （原始内容存档于2019-08-16）.  引文格式1维护：冗余文本 (link) Richard Brusca. Isopoda. Tree of Life Web Project. 1997-08-06 [2010-03-27]. （原始内容存档于2016-03-22）.  Schram, =Frederick R. Isopod from the Pennsylvanian of Illinois. Science. 1970, 169 (3948): 854–5. doi:10.1126/science.169.3948.854.  M. Schotte, C. B. Boyko, N. L. Bruce, J. Markham, G. C. B. Poore, S. Taiti & G. D. F. Wilson. World List of Marine, Freshwater and Terrestrial Isopod Crustaceans. World Register of Marine Species. [2009-02-19]. （原始内容存档于2019-10-23）.  S. J. Keable, G. C. B. Poore & G. D. F. Wilson. Australian Isopoda: Families. Australian Museum. 2002-10-02 [2010-03-27]. （原始内容存档于2018-10-10）.  R. C. Brusca & M. R. Gilligan. Tongue replacement in a marine fish (Lutjanus guttatus) by a parasitic isopod (Crustacea: Isopoda). Copeia. 1983, 3: 813–6. doi:10.2307/1444352.  Martin, Joel W.; Davis, George E. An Updated Classification of the Recent Crustacea (PDF). Natural History Museum of Los Angeles County. 2001: 132 pp [2010-03-27]. （原始内容存档 (PDF)于2013-05-12）.  Torben Riehl, Katharina Ellen Schienbein and Constantine Mifsud. 2024. A New Species of Mexicope Hooker, 1985 (Crustacea, Isopoda) — the First Record of Acanthaspidiidae Menzies, 1962 from the Mediterranean Sea. Biodiversity Data Journal. 12: e121508. DOI: 10.3897/BDJ.12.e121508 Five new species of Exalloniscus Stebbing, 1911 (Crustacea, Isopoda, Oniscidea) from China. Zoosystematics and Evolution. [2024-04-14].  维基共享资源上的相关多媒体资源：等足目