Leptodora

{{Short description|Genus of small freshwater animals}} {{Automatic taxobox | image = Leptodora.png | image_caption = ''Leptodora kindtii'' | grandparent_authority = G. O. Sars, 1865 | parent_authority = Lilljeborg, 1861 | taxon = Leptodora | authority = Lilljeborg, 1861 | subdivision_ranks = Species | subdivision = *'''''Leptodora kindtii''''' (Focke, 1844) *'''''Leptodora richardii''''' Korovchinsky, 2009 | synonyms = ''Hyalosoma'' Wagner, 1868 }}

'''''Leptodora''''' is a genus containing two species of large, nearly transparent predatory water fleas. They grow up to {{convert|21|mm|abbr=on}} long, with two large antennae used for swimming and a single compound eye. The legs are used to catch copepods that it comes into contact with by chance. ''Leptodora kindtii'' is found in temperate lakes across the Northern Hemisphere and is probably the only water flea species ever described in a newspaper; ''L. richardi'' is only known from eastern Russia. For most of the year, ''Leptodora'' reproduces parthenogenetically, with males only appearing late in the season, to produce winter eggs which hatch the following spring. ''Leptodora'' is the only genus in its family, the '''Leptodoridae''', and suborder, '''Haplopoda'''.

==Description== Adults of ''Leptodora'' are the largest planktonic cladocerans native to North America;<ref>{{cite web |url=http://cfb.unh.edu/CFBkey/html/Organisms/CCladocera/FLeptodoridae/GLeptodora/Leptodora_kindti/leptodorakindti.html |title=''Leptodora kindti'' |work=An Image-Based Key to the Zooplankton of the Northeast (USA) |publisher=University of New Hampshire |access-date=2010-03-19 |archive-url=https://web.archive.org/web/20100726012546/http://cfb.unh.edu/CFBkey/html/Organisms/CCladocera/FLeptodoridae/GLeptodora/Leptodora_kindti/leptodorakindti.html |archive-date=2010-07-26 |url-status=dead }}</ref> reports vary concerning the largest size, but adult females typically grow to {{convert|12|mm|abbr=on}} long,<ref>{{cite journal |doi=10.4319/lo.1990.35.5.1091 |title=Trophic interactions of ''Leptodora'' in Lake Mendota |author1=Cynthia C. Lunte |author2=Chris Luecke |journal=Limnology and Oceanography |volume=35 |issue=5 |year=1990 |pages=1091–1100 |jstor=2837489|bibcode=1990LimOc..35.1091L |doi-access=free }}</ref> but with some reports of females up to {{convert|21|mm|abbr=on}}.<ref name="Andrews"/> They are about 98% transparent,<ref name="CMich">{{cite web |url=http://www.cst.cmich.edu/users/mcnau1as/zooplankton%20web/Leptodora%5CLeptodora.htm |title=''Leptodora kindti'' |work=Zooplankton of the Great Lakes |publisher=Central Michigan University |accessdate=March 10, 2010}}</ref> as a defense against predation by fish.<ref>{{cite journal |doi=10.1093/plankt/fbi033 |title=Contrasting life histories of the predatory cladocerans ''Leptodora kindtii'' and ''Bythotrephes longimanus'' |author=Donn K. Branstrator |journal=Journal of Plankton Research |volume=27 |issue=6 |pages=569–585 |year=2005 |doi-access=free }}</ref> Lilljeborg notes:<ref name="Lill"/> <blockquote>{{Lang|de|Das Weibchen ist in so hohem Grade durchsichtig, in wahrem Sinne »wasserhell», dass oft nur die Bewegungen ihr Dasein in dem Wasser verrathen. Bei auffallendem Sonnenlicht wird gewöhnlich der Schatten früher als das Thier selbst entdeckt.}}</blockquote> <blockquote>The female is transparent to such a high degree, literally "as clear as water", that her presence is often only given away by her movements. In bright sunlight, the shadow is normally seen before the animal itself.</blockquote> The male is similarly transparent.<ref name="Lill"/> The abdomen is elongated, but the carapace is small and only covers the brood pouch.<ref name="CMich"/>

The six pairs of thoracic appendages form a "feeding basket" which is used to capture prey.<ref>{{cite journal |doi=10.4319/lo.1995.40.4.0834 |title=Seasonal changes in size of the feeding basket of ''Leptodora kindtii'' (Focke) in Lago Maggiore as related to variations in prey size selection |author1=Marina Manca |author2=Patrizia Comoli |journal=Limnology and Oceanography |volume=40 |issue=4 |year=1995 |pages=834–838 |jstor=2838319|bibcode=1995LimOc..40..834M |doi-access=free }}</ref> The second antennae are used for swimming, while the first antennae are rudimentary in females but elongated in males, where they are used in sexual reproduction.<ref name="CMich"/> There is a single large compound eye which takes up much of the animal's head.<ref name="CMich"/> It comprises around 500 facets, which are spherically arranged, and the whole eye is movable by up to 10° in any direction.<ref>{{cite journal |doi=10.1083/jcb.26.3.968 |journal=Journal of Cell Biology |year=1965 |volume=26 |issue=3 |pages=968–973 |pmid=19866691 |title=The compound eye of a crustacean, ''Leptodora kindtii'' |author1=J. J. Wolken |author2=G. J. Gallik |pmc=2106796}}</ref>

==Distribution== ''Leptodora kindtii'' is widespread in northern temperate lakes. In North America, it occurs as far south as Texas and Oklahoma.<ref>{{cite journal |doi=10.2307/3671192 |title=Discovery of ''Leptodora kindtii'' (Focke) (Crustacea: Clad-Ocera) in Oklahoma and Texas |author1=Jack R. Holt |author2=David S. White |author3=Alan P. Covich |journal=The Southwestern Naturalist |volume=23 |issue=4 |year=1978 |pages=686–688 |jstor=3671192}}</ref> It is also found across Europe, in parts of North Africa, northern Arabia, and in Asia (north of the Himalaya).<ref name="CMich"/>

==Ecology and behaviour== [[File:Daphnia pulex.png|thumb|right|''Daphnia'' is an important prey item for ''Leptodora kindtii''.]]  ''Leptodora kindtii'' is a voracious predator and is capable of controlling numbers of its preferred prey items,<ref name="Neusiedl">{{cite journal |author=Alois Herzig |s2cid=7755718 |year=1995 |title=''Leptodora kindti'': efficient predator and preferred prey item in Neusiedler See, Austria |journal=Hydrobiologia |volume=307 |issue=1–3 |pages=273–282 |editor1=P. Larsson |editor2=L. J. Weider |doi=10.1007/BF00032021}}</ref> which are generally juveniles of ''Daphnia'', ''Bosmina'', ''Ceriodaphnia'', ''Diaphanosoma'', ''Diaptomus'', ''Polyphemus'' and ''Cyclops''.<ref name="CMich"/> It seems to encounter its prey by chance, with contact initiating a reflex, in which the abdomen is brought forward to close the feeding basket. In many cases, the prey escapes this haphazard response. Juvenile ''Daphnia'' are slower than adults to respond to the predator's attack, and are therefore more likely to be caught.<ref name="Browman">{{cite journal |doi=10.1093/plankt/11.5.1075 |author1=Howard I. Browman |author2=Silke Kruse |author3=W. John O'Brien |year=1989 |title=Foraging behavior of the predaceous cladoceran, ''Leptodora kindti'', and escape responses of their prey |journal=Journal of Plankton Research |volume=11 |issue=5 |pages=1075–1088 }}</ref>

The most important predators of ''Leptodora'' are fishes, including whitefish, perch, ziege and bleak.<ref name="Neusiedl"/>

In Lake Biwa, Japan, ''L. kindtii'' is parasitised by the nematode ''Raphidascaris biwakoensis'', a parasite of fish.<ref>{{cite journal |doi=10.3354/dao032157 |author1=F. Moravec |author2=K. Nasagawa |author3=Y. Tanaka |author4=T. Narita |year=1998 |journal=Diseases of Aquatic Organisms |volume=32 |pages=157–160 |title=Role of ''Leptodora kindti'' (Cladocera: Leptodoridae) in the life cycle of ''Raphidascaris biwakoensis'' (Nematoda: Anisakidae), a fish parasite in Lake Biwa, Japan |issue=2 |pmid=9676256 |url=https://www.int-res.com/articles/dao/32/d032p157.pdf |doi-access=free }}</ref>

==Life cycle== Female ''Leptodora'' produce a brood of eggs through parthenogenesis every 12 hours.<ref name="Vijv"/> These eggs hatch into a larval stage about {{convert|2|mm}} long. There are six further instars before the adult form is reached with a length of {{convert|6|mm}}.<ref name="Vijv">{{cite journal |title=Effect of temperature on development and growth of the raptorial cladoceran ''Leptodora kindtii'' under laboratory conditions |author1=Jacobus Vijverberg |author2=Hans Peter Koelewijn |journal=Freshwater Biology |volume=49 |pages=1415–1422 |year=2004 |doi=10.1111/j.1365-2427.2004.01276.x |issue=11}}</ref> The time taken to reach adulthood is temperature dependent, but takes between 3 and 6 days.<ref name="Vijv"/> For most of the year, reproduction is parthenogenetic, with eggs being produced by females without males being present in the population.<ref name="CMich"/> In the autumn, parthenogenetically produced males begin to appear;<ref name="Andrews">{{cite journal |doi=10.2307/3223355 |title=Growth studies on parthenogenetically produced male and female ''Leptodora kindtii'' (Focke) |author=Ted F. Andrews |journal=Transactions of the American Microscopical Society |volume=72 |issue=1 |year=1953 |pages=9–17 |jstor=3223355}}</ref> males and females then reproduce sexually. The resulting eggs sink to the bottom where they overwinter,<ref name="Lill"/> hatching the following year as nauplius-like larvae.<ref name="CMich"/>

==Related taxa== ''Leptodora'' is so distinct from other cladocerans that some authors have suggested grouping all other cladocerans into a clade called "Eucladocera", with ''Leptodora'' as its sister group. It is now believed, however, that ''Leptodora'' is sister to Onychopoda, being the only genus in the family '''Leptodoridae''' and the subclass '''Haplopoda'''.<ref name="M&D">{{cite book |url=http://atiniui.nhm.org/pdfs/3839/3839.pdf |title=An Updated Classification of the Recent Crustacea |author1=Joel W. Martin |author2=George E. Davis |year=2001 |pages=132 |publisher=Natural History Museum of Los Angeles County |archive-date=2013-05-12 |access-date=2010-03-19 |archive-url=https://web.archive.org/web/20130512091254/http://atiniui.nhm.org/pdfs/3839/3839.pdf |url-status=dead }}</ref> Features which separate it from other families include its large size, the lack of branchial appendages (gills) on its legs, the reduction of the carapace, and the fact that the winter eggs hatch as nauplii.<ref name="CMich"/>

==Taxonomic history== thumb|right|''Leptodora'' was first found in the ''Bremer Stadtgraben'', and described by the local scientist G. W. Focke. ''Leptodora kindtii'' is "probably the only cladoceran ever described in a newspaper".<ref name="Dumont">{{cite journal |title=''Leptodora kindtii'' (Focke, 1844) from Bremen, Germany: discovered, forgotten, and rediscovered |author1=Henri J. Dumont |author2=Werner Hollwedel |journal=Crustaceana |volume=82 |issue=11 |year=2009 |pages=1457–1461 |doi=10.1163/001121609X12511103974457}}</ref> The German microscopist Gustav Woldemar Focke organised a scientific meeting in Bremen in 1844 together with the pharmacist Georg Christian Kindt. He studied the fauna of the ditches surrounding the city (the ''{{lang|de|Bremer Stadtgraben}}'') and displayed live specimens at the meeting. During the meeting, he also published a description of the species in the ''{{Lang|de|Weser-Zeitung}}'' on Sunday September 22, 1844, placing the species in the genus ''Polyphemus''.<ref name="Dumont"/> However, this description was ignored by the scientific community, and Wilhelm Lilljeborg described the species in 1861 with the name ''Leptodora hyalina''. The synonymy was not noticed until Simon Albrecht Poppe informed Lilljeborg of it in 1889,<ref name="Dumont"/> and Lilljeborg corrected the error in his 1900 monograph.<ref name="Lill">{{cite book |author=Wilhelm Lilljeborg |year=1900 |title=Cladocera Sueciae; oder Beiträge zur kenntniss der in Schweden lebenden Krebsthiere von der Ordnung der Branchiopoden und der Unterordnung der Cladoceren |publisher=Druck der Akademischen buchdruckerei E. Berling |location=Uppsala |url=https://archive.org/details/cladocerasueciae00lill |pages=[https://archive.org/details/cladocerasueciae00lill/page/650 650]–658, Tab. 87|author-link=Wilhelm Lilljeborg }}</ref>

In 2009, a second species, ''Leptodora richardii'', was described from individuals collected from lakes in the Amur River basin, including Lake Bolon.<ref>{{cite journal |author=Nikolai M. Korovchinsky |year=2009 |title=The genus ''Leptodora'' Lilljeborg (Crustacea: Bracnhiopoda: Cladocera) is not monotypic: description of a new species from the Amur River basin (Far East of Russia) |journal=Zootaxa |volume=2120 |pages=39–52 |url=http://www.mapress.com/zootaxa/2009/f/z02120p052f.pdf |doi=10.11646/zootaxa.2120.1.5 }}</ref>

===Synonyms=== Synonyms of ''Leptodora kindtii'' include:<ref>{{cite web |url=http://fada.biodiversity.be/CheckLists/Crustacea-Cladocera.pdf |title=Crustacea-Cladocera checkList |work=Freshwater Animal Diversity Assessment (FADA) Project |publisher=Belgian Biodiversity Platform |date=October 20, 2010 |accessdate=November 7, 2010}}</ref> *''Polyphemus kindti'' Focke, 1844 *''Hyalosoma dux'' Wagner, 1868 *''Leptodora angusta'' Sars, 1890 *''Leptodora hyalina'' Lilljeborg, 1861 *''Leptodora pellucida'' Joseph, 1882

===Etymology=== The name ''Leptodora'' is from the Greek words ''{{lang|el|leptos}}'' and ''{{lang|el|dora}}'', collectively meaning thin-skinned.<ref name="Lil62">{{cite journal |author=Wilhelm Lilljeborg |year=1862 |title=An Account of two remarkable Crustacea of the Order Cladocera |journal=Annals and Magazine of Natural History |volume=9 |series=3rd series |issue=50 |pages=132–136|author-link=Wilhelm Lilljeborg |doi=10.1080/00222936208681196 |url=https://www.biodiversitylibrary.org/part/64591 }}</ref> The specific epithet ''kindtii'' is presumed to refer to G. C. Kindt, who worked closely with Focke.<ref name="Dumont"/> The alternative spelling ''kindti'' is sometimes encountered,<ref>{{cite book |title=Zooplankton of the Great Lakes: a guide to the identification and ecology of the common crustacean species |publisher=University of Wisconsin Press |year=1984 |isbn=978-0-299-09820-9 |author1=Mary D. Balcer |author2=Nancy L. Korda |author3=Stanley I. Dodson |chapter=Life history and ecology of the major crustacean species |pages=49–109}}</ref> but is no longer considered correct under the International Code of Zoological Nomenclature.<ref name="Olesen">{{cite journal |title=On the ontogeny of ''Leptodora kindtii'' (Crustacea, Branchiopoda, Cladocera), with notes on the phylogeny of the Cladocera |author1=Jørgen Olesen |author2=Stefan Richter |author3=Gerhard Scholtz |year=2003 |journal=Journal of Morphology |volume=256 |issue=3 |pages=235–259 |doi=10.1002/jmor.10043|pmid=12655608 |s2cid=24239891 }}</ref> The epithet ''hyalina'', used by Lilljeborg, is from the Greek ''{{lang|el|ὕαλος}}'', and means glassy.<ref name="Lil62"/>

==External links== {{Wikispecies|Leptodora}} {{Portal|Crustaceans}} *{{cite web |url=http://www.cnas.missouristate.edu/zooplankton/leptodora_kindtii.htm |title=''Leptodora kindtii'' |publisher=Missouri State University |date=August 2006}} *{{cite web |url=http://www.zooplankton-online.net/creature_of_the_month_july_2005.html |title=Creature of the Month: ''Leptodora kindtii'' |date=July 2005 |publisher=Zooplankton-online.net |access-date=2010-03-19 |archive-url=https://web.archive.org/web/20061019055657/http://www.zooplankton-online.net/creature_of_the_month_july_2005.html |archive-date=2006-10-19 |url-status=dead }} *{{cite web |url=http://cfb.unh.edu/CFBkey/media/leptodora2/leptodora1.html |title=''Leptodora kindtii'' swimming |format=QuickTime |publisher=University of New Hampshire }}{{Dead link|date=February 2020 |bot=InternetArchiveBot |fix-attempted=yes }} *{{cite web |url=http://cfb.unh.edu/CFBkey/media/leptodora2/leptodora2.html |title=''Leptodora kindtii'' swimming and bending |format=QuickTime |publisher=University of New Hampshire |access-date=2010-03-19 |archive-url=https://web.archive.org/web/20060905022505/http://cfb.unh.edu/cfbkey/media/leptodora2/leptodora2.html |archive-date=2006-09-05 |url-status=dead }}

==References== {{Reflist|32em}}

Category:Cladocera Category:Branchiopoda genera Category:Taxa named by Wilhelm Lilljeborg