Moerisia maeotica (Ostroumov, 1896)
Synonyms: Thaumantias maeotica Ostroumov, 1896; Moerisia inkermanica Paltschikowa-Ostroumova, 1925; Ostroumovia inkermanica Valkanov, 1933; Pontia ostroumovi Paspalev, 1936; Odessia maeotica Paspalev, 1937.
Common names: None.
Order (Scientific): (HYDROZOA) LEPTOLIDA.
Family (Scientific): MOERISIIDAE.
Taxonomic descriptions: The species has form of both polypus and planktonic medusa. The polypi may be as isolated or bipolar colonies, formed through a fusion the bases basis of two polypi. The body has 3-12 tentacles with an irregular arrangement. Medusa develops only on polypus’ body. It has a spherical shape with a diameter up to 20 mm (at sexual maturity). On the borders of umbrella, there are up to 36 tentacles which have oceli at their base. Medusa with 4 radial ducts and an oral cavity with 4 lobs. The gonades on the basis of the oral cavity descend in radial ducts to the margins of the umbrella. A thick and transparent mesoglea.
Black Sea Regional level: VU
Subregion level: EN (Romanian sector), VU (Romanian and Ukrainian sector)
Distribution: In the Sea of Azov, Black Sea, limans of the Azov-Black Sea basin. Range includes freshwater areas of the Mediterranean Sea (in particular the eastern part of its basin - Adriatic Sea), Atlantic coast of Africa. After the opening of the Volga-Don Canal in 1952 the species penetrated into the Caspian Sea.
Habitat type, Critical habitats, Limiting factors: Polyps occur in the upper sublitoral. Can attach to rocks, broken wood, different floating objects. Jellyfish inhabit the near surface layers of the water body.
Biology: Live at temperatures of 15-25°C and a salinity of 0.5-3.5 ppt. Feed on zooplankton. The life cycle includes a succession of polypoid and jellyfish stages. In the Black Sea produces by the budding of polyps in August - September, forms weakly branched laminated colonies. The polyp has a thin long stalk. The jellyfish becomes mature in 30-40 days after separating from the polyp.
Population trends: Exact numbers unknown. Rarely encountered.
Threats: Increase in salinity, pollution of water bodies.
Conservation measures taken: Included in Red Data Books of Ukraine and the Black Sea.
Conservation measures proposed: Create conditions for normal species reproduction, including the prevention of pollution of freshwater areas of the sea.
Compiled by: B.G.Alexandrov, A.Petranu.