|
The warty comb jelly or sea walnut〔(【引用サイトリンク】title=Common Names for Sea Walnut (Mnemiopsis leidyi) )〕 (''Mnemiopsis leidyi'') is a species of tentaculate ctenophore (comb jelly), originally native to the western Atlantic coastal waters. Three species have been named in the genus ''Mnemiopsis'', but they are now believed to be different ecological forms of a single species ''M. leidyi'' by most zoologists. ==Description and ecology== ''Mnemiopsis'' have a lobed body that is oval-shaped and transparent, with four rows of ciliated combs that run along the body vertically and glow blue-green when disturbed. They have several feeding tentacles. Unlike cnidarians, ''Mnemiopsis'' doesn't sting. Their body contains 97% water. They are small organisms, having a maximum body length of roughly and a diameter of . It is euryoecious, tolerating a wide range of salinity (2 to 38 psu), temperature (), and water quality. ''Mnemiopsis'' is a carnivore that consumes zooplankton including crustaceans,〔Kube, Sandra; Postel, Lutz; Honnef, Christopher & Augustin, Christina B. (2007): ''Mnemiopsis leidyi'' in the Baltic Sea - distribution and overwintering between autumn 2006 and spring 2007. ''Aquatic Invasions'' 2 (2): 137–145. () PDF fulltext〕 other comb jellies, and eggs and larvae of fish; it is sometimes known to eat smaller individuals of its own kind. It also has several other predators. Many are vertebrates, including species of birds and fish. Some predators include other members of gelatinous zooplankton such as ''Beroe'' ctenophores and various Scyphozoa (jellyfish). This comb jelly has the capacity for self-fertilization, as they are hermaphroditic. They have gonads that contain the ovary and spermatophore bunches in their gastrodermis. This animal carries 150 eggs along each meridional canal. Eggs and sperm are released into the water column where external fertilization takes place. The spawning commences at late evening or at 1:00 or 2:00 a.m. The spawning eggs develop a thick outer layer within 1 minute after touching the seawater. As many as 10,000 eggs can be produced from large specimens in areas with good prey abundance. Egg production can start when the animals reach about 15 mm in length. Egg production increases with ctenophore size, and it is unclear when senescence occurs. The species is blind, has no brain and moves so slowly that it is referred to as "sea walnut". 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mnemiopsis」の詳細全文を読む スポンサード リンク
|