A general term for echinoderms belonging to the class Echinoidea. All sea urchins are marine, and their habitats range from under stones in the intertidal zone or in rock cavities to the deep sea at depths of up to 6,000 meters. Currently, about 900 species are known, with the greatest number found in the Pacific and Indian Oceans, and found in Africa, Australia, Japan, and Hawaii. [Form and Function] Sea urchins are broadly divided into regular and irregular sea urchins. Regular sea urchins have hemispherical shells, such as the sea urchin (illustration) and the purple sea urchin (illustration), while irregular sea urchins have heart-shaped or flattened oval shells, such as the sea urchin (illustration) and the octopus pillow (illustration). Source: Heibonsha World Encyclopedia, 2nd Edition Information |
ウニ綱に属する棘皮(きよくひ)動物の総称。ウニ類はすべて海産で,潮間帯の石の下や岩のくぼみにすむものから,水深6000mの深海にまで生息の範囲を広げている。現在約900種が知られており,太平洋~インド洋海域がもっとも種類が多く,アフリカ,オーストラリア,日本,ハワイへと広がっている。 [形態と機能] ウニ類は正形類と不正形類とに大別される。正形類はバフンウニ(イラスト)やムラサキウニ(イラスト)などのように半球状の殻をもち,不正形類はブンブクチャガマ(イラスト)やタコノマクラ(イラスト)の殻のように心臓形や扁平な楕円形をしている。 出典 株式会社平凡社世界大百科事典 第2版について 情報 |
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