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Holoplankton are organisms that are planktonic (they live in the water column and cannot swim against a current) for their entire life cycle. Examples of holoplankton include some diatoms, radiolarians, some dinoflagellates, foraminifera, amphipods, krill, copepods, and salps, as well as some gastropod mollusk species. Holoplankton dwell in the pelagic zone as opposed to the benthic zone. Holoplankton include both phytoplankton and zooplankton and vary in size. The most common plankton are protists. ==Reproduction== Holoplankton have unique traits that make reproduction in the water column possible. Both sexual and asexual reproduction are used depending on the type of plankton. Some invertebrate holoplankton release sperm into the water column which are then taken up by the females for fertilization. Other species release both sperm and egg to increase the likelihood of fertilization. Environmental, mechanical, or chemical cues can all trigger this release.〔(【引用サイトリンク】url=http://depts.washington.edu/fhl/zoo432/plankton/plreproduction/reproduction.html )〕 Diatoms are single celled phytoplankton that can occur as individuals or as long chains. They can reproduce sexually and asexually. Diatoms are important oxygen producers and are usually the first step in the food chain.〔 Copepods are small holoplanktonic crustaceans that swim using their hind legs and antennae. 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「Holoplankton」の詳細全文を読む スポンサード リンク
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