Bdelloidea

Bdelloid rotifers; Temporal range:
	SEM showing morphological variation of bdelloid rotifers and their jaws
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Rotifera
Superclass:	Eurotatoria
Class:	Bdelloidea; Hudson, 1884

Bdelloidea /ˈdɛlɔɪdiə/ (Greek βδέλλα, bdella, "leech") is a class of rotifers found in freshwater habitats all over the world. There are over 450 described species of bdelloid rotifers (or 'bdelloids'),^[1] distinguished from each other mainly on the basis of morphology.^[2] The main characteristics that distinguish bdelloids from related groups of rotifers are exclusively parthenogenetic reproduction and the ability to survive in dry, harsh environments by entering a state of desiccation-induced dormancy (anhydrobiosis) at any life stage.^[3] They are often referred to as "ancient asexuals" due to their unique asexual history that spans back to over 25 million years ago through fossil evidence.^[4] Bdelloid rotifers are microscopic organisms, typically between 150 and 700 μm in length.^[3] Most are slightly too small to be seen with the naked eye, but appear as tiny white dots through even a weak hand lens, especially in bright light. In June 2021, biologists reported the restoration of bdelloid rotifers after being frozen for 24,000 years in the Siberian permafrost.^[5]

^ Donner, Josef (1965). "Ordnung Bdelloidea (Rotatoria, Rädertiere)". Bestimmungsbücher zur Bodenfauna Europas, volume 6. Berlin: Akademie Verlag. OCLC 6733231. and Segers, Hendrik (2007). "Annotated checklist of the rotifers (Phylum Rotifera), with notes on nomenclature, taxonomy and distribution". Zootaxa. 1590: 3–104. Abstract.
^ Segers, Hendrick (2007). Annotated checklist of the rotifers (Phylum Rotifera), with notes on nomenclature, taxonomy and distribution (PDF). Auckland: Magnolia Press. ISBN 978-1-86977-129-4.
^ ^a ^b Ricci, Claudia (2000). "Key to the identification of the genera of bdelloid rotifers". Hydrobiologia. 418: 73–80. doi:10.1023/A:1003840216827. S2CID 44054669.
^ Poinar Jr., G. O.; Ricci, Claudia (1992). "Bdelloid rotifers in Dominican amber: Evidence for parthenogenetic continuity". Experientia. 48 (4): 408–410. doi:10.1007/BF01923444. S2CID 13098228.
^ Renault, Marion (7 June 2021). "This Tiny Creature Survived 24,000 Years Frozen in Siberian Permafrost - The microscopic animals were frozen when woolly mammoths still roamed the planet, but were restored as though no time had passed". the New York Times. Retrieved 7 June 2021.

[1] Donner, Josef (1965). "Ordnung Bdelloidea (Rotatoria, Rädertiere)". Bestimmungsbücher zur Bodenfauna Europas, volume 6. Berlin: Akademie Verlag. OCLC 6733231. and Segers, Hendrik (2007). "Annotated checklist of the rotifers (Phylum Rotifera), with notes on nomenclature, taxonomy and distribution". Zootaxa. 1590: 3–104. Abstract.

[Segers2007-2] Segers, Hendrick (2007). Annotated checklist of the rotifers (Phylum Rotifera), with notes on nomenclature, taxonomy and distribution (PDF). Auckland: Magnolia Press. ISBN 978-1-86977-129-4.

[Ricci2000-3] Ricci, Claudia (2000). "Key to the identification of the genera of bdelloid rotifers". Hydrobiologia. 418: 73–80. doi:10.1023/A:1003840216827. S2CID 44054669.

[4] Poinar Jr., G. O.; Ricci, Claudia (1992). "Bdelloid rotifers in Dominican amber: Evidence for parthenogenetic continuity". Experientia. 48 (4): 408–410. doi:10.1007/BF01923444. S2CID 13098228.

[NYT-20210607-5] Renault, Marion (7 June 2021). "This Tiny Creature Survived 24,000 Years Frozen in Siberian Permafrost - The microscopic animals were frozen when woolly mammoths still roamed the planet, but were restored as though no time had passed". the New York Times. Retrieved 7 June 2021.

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