Baikal World - information about invertebrates of Baikal lake and Baikal region
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Invertebrates of Lake Baikal

Baikal Invertebrates Recently about 2635 animal species have been registered in the open part of Baikal. Most abundant of them are invertebrates: infusoria (about 400 species), sponges (10 species), flat worms (over 100 species), free-living nematodes (about 80 species), arthropods (about 700 species) molluscs (over 170 species) etc. Due to some of these organisms the ability of Lake Baikal for self-purification is one of the greatest. They purify water.

The systematic composition of invertebrate fauna of Baikal can not be considered finally defined. Annually tens of new species are described by experts in zoology (mainly - from the laboratory of hydrobiology and systematics of fresh-water invertebrates of Limnological Institute), unknown so far animals are discovered.

Three groups of organisms are distinguished according to their inhabitation in Baikal as in any other reservoir: benthos - bottom inhabitants; bentho-pelagic, occupying near-bottom water layers and pelagic, inhabiting water body (pelagial). Benthos organisms reach greatest diversity in the Lake (over 1000 species).

Infusoria - most variable one-celled organisms of Baikal. They are generally divided into 2 groups; free-living (benthic and pelagic), and also symbiotic infusoria. In contrast to other fresh-water reservoirs, Baikal produced several endemic communities of free-living infusoria both in waterbody, and in the bottom. L. A. Obolkina found amazing infusoria fauna inhabiting microscopic space between sand particles (cyliopsammon). One of them is a new species and new genus Aleksandrina baicalensis Obolkina, n. gen., n. sp. Similar organisms, as a rule, inhabit only seas. Baikal is an exclusion to this. Symbiotic infusorians are unusual and diverse in form. They live on other bigger animals, for example, crustaceans, molluscs. All Baikal infusoria - symbionts (about 30 genera and 200 species) are endemic.

Flat worms - planarians. Looking like a baby-bear with many eyes, Papilloplana sp., which is only 2 cm long; largest fresh-water planaria of the World-Baikaloplana valida, which is 40 cm long, when moving. Giants, common at the depth over 100 m, are predators and therefore are provided with suckers - Baikaloplana has over 100 ones on both sides of the body; another giant - Rimacephalus arecepta having two ventral ones on the frontal end of the body - is often taken out the deep-water nets, when it eating a fish there.

Baikal Invertebrates Lubomirskia. Crust and branched forms of endemic sponge Lubomirskia baicalensis are real submarine forests at the depths of 2 to 40 m. Externally the sponges resemble fantastic plants. But they are real animals, ones of the first many-celled organisms (Metazoa), inhabiting the Earth. Their green colour is due to small symbiotic algae - zoochlorella.

Epishura - one of the most well-known
invertebrates of Baikal. This small, 1.5 mm long crustacean plays an important role in the pelagic ecosystem. It consumes the majority of Baikal algae and serves an essential feeding object of famous omul. The epischura plays an exceptional part in Baikal's life circle. Without any exaggeration, one can say that the epischura is the major filter of Baikal. According to academician G. Galazy, a well-known scientist (Lake Baikal, 1979), «throughout the year all crustaceans of this species filter from 500 to 1,000 cubic kilometres of the Baikal water or more, which is 10-15 times more the annual inflow of water from all tributaries». The epischura lives only in cold clean water with constant chemical composition and high saturation with oxygen. Biomass of Epishura and cyclop (aprox.) = 1800000 ton.

One-celled and small invertebrate animals, inhabiting the Lake pelagic zone are joined into zooplankton group. They posess such apparatus, that support them in water body. They are free-moving together with Lake waters and occur up to great depths. Total biomass of zooplancton = 4600000 ton.
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