Hydrodictyon reticulatum; water net

Japanese: アミミドロ（英語表記）Hydrodictyon reticulatum; water net

A species of green algae in the family Polypodium, order Chlorococcales. It is often found in freshwater such as rice paddies. The algae are named after the long cylindrical cells that are arranged in a hexagonal mesh with each end of two other cells touching each other. Each cell is multinucleated and has a reticulated chloroplast, but eventually small reticulated daughter bodies are produced within the cell, the old cell membrane breaks, and each daughter body elongates to become a new individual. Sometimes the cell contents divide to become numerous two-flagellated zoospores that multiply asexually. It is also known to produce homotypic motile gametes and reproduce sexually. Since there is no reduction by the first division during zygote germination, this alga is thought to be polyploid.

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

Japanese:

緑藻類クロロコックム目アミミドロ科の1種。しばしば水田など淡水中にみられる。その藻体は，長円筒形の細胞が各端で他の2細胞に接して六角の網目をつくるように並んでいるので，この名がつけられた。各細胞は多核で網状の葉緑体をもつが，やがてその細胞内にそれぞれ小さな網目状の娘体を生じ，古い細胞膜は破れ，各娘体はそのまま伸びて新個体となる。ときに，細胞内容が分れて多数の2鞭毛を有する遊走子となり無性的にふえる。また同型の運動性配偶子を生じ，有性生殖をすることも知られている。接合子の発芽時の第1分裂によって減数しないので，この藻は倍数体であると考えられる。

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