Editing Lake Baikal (section)

====Aquatic worms====
With almost 200 described species, including more than 160 endemics, the center of diversity for aquatic freshwater [[oligochaetes]] is Lake Baikal.<ref name=SegersMartens>Segers, H.; and Martens, K; editors (2005). ''The Diversity of Aquatic Ecosystems.'' pp. 43–44. Developments in Hydrobiology. Aquatic Biodiversity. {{ISBN|1-4020-3745-7}}</ref> A smaller number of other freshwater annelids is known: 30 species of [[leech]]es (Hirudinea),<ref>Kaygorodova, I.A.; and N.M. Pronin (2013). ''New Records of Lake Baikal Leech Fauna: Species Diversity and Spatial Distribution in Chivyrkuy Gulf.'' ScientificWorldJournal. 2013(2013): 206590. {{doi|10.1155/2013/206590}}</ref> and 4 [[polychaetes]].<ref name=SegersMartens/> Several hundred species of [[nematode]]s are known from the lake, but a large percentage of these are [[Undescribed taxon|undescribed]].<ref name=SegersMartens/>
[[File:Lubomirskia-baicalensis.jpg|thumb|upright|Museum specimen of the branching sponge ''[[Lubomirskia baicalensis]]'' (living are brighter green)]]
More than 140 endemic [[flatworm]] (Plathelminthes) species are in Lake Baikal, where they occur on a wide range of bottom types.<ref name=flatworm>Baikal.ru: [http://baikal.ru/en/baikal/excursion/planaria.html Flatworms (Plathelminthes).] Retrieved 7 June 2017.</ref> Most of the flatworms are predatory, and some are relatively brightly marked. They are often abundant in shallow waters, where they are typically less than {{convert|2|cm|in|abbr=on|0}} long, but in deeper parts of the lake, the largest, ''Baikaloplana valida'', can reach up to {{convert|30|cm|ft|abbr=on|0}} when outstretched.<ref name=Shahgedanova2002/><ref name=flatworm/>