Leptodora richardi

Japanese: ノロミジンコ（英語表記）Leptodora richardi

Class: Branchiopods, Order: Bivalvia, Family: Leptodoridae. With a body length of about 1 cm, this is the largest species of water flea. The body is transparent and slender, cylindrical, with large compound eyes taking up most of the round head. The second antennae are large and help with swimming. The dorsal shell is small and pouch-like, and is merely attached to the end of the thorax. There is only one genus in the family Harpacticidae, and two species in the genus Harpacticida. The species found in abundance in Lake Biwa in Shiga Prefecture and Lake Kasumigaura in Ibaraki Prefecture was given the scientific name L. kindtii , but in 2009 it was identified as L. richardi , which was described from the Amur River basin. Its movement is very slow, but it moves significantly vertically during the day and night. (→Crustacea, Branchiopods, Arthropods)

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

鰓脚綱双殻目ノロミジンコ科 Leptodoridae。体長は 1cmほどで，ミジンコ類中の最大種。体は透明感のある細長い円筒形で，丸い頭部のほとんどを大きな複眼が占める。第2触角は大きく，遊泳に役立つ。背殻は小さな嚢状で，胸部末端に付着しているにすぎない。ノロミジンコ科は 1属のみで，ノロミジンコ属は 2種が知られている。滋賀県の琵琶湖や茨城県の霞ヶ浦に多産する種には L. kindtii の学名が与えられていたが，2009年にアムール川流域から記載された L. richardi とされる。運動は非常にゆるやかであるが，昼夜の垂直移動が顕著である。（→甲殻類，鰓脚類，節足動物）

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