A general term for species belonging to the Anthozoa class of the phylum Cnidaria. Existing species are broadly divided into the Octocorallia and Hexacorallia subclasses. They only have polyp-type (→Polyps), and there is no medusa-type (→Medusa) stage in their life cycle. Polyps are cylindrical, with the mouth plate at the top surrounded by a crown of tentacles (→Tentacorals). The external form is radially symmetrical, but the inside is bilaterally symmetrical (→Symmetry). Many have a calcareous or keratinous exoskeleton or endoskeleton. All are marine. They live alone or in colonies, and many are attached to other objects. There are about 6,000 known species in the world, including zoanthids and anthocorals (about 1,500 of which are found in Japan). (→Cnidaria, Invertebrates) Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information |
刺胞動物門花虫綱に属する種類の総称。現生種は八放サンゴ亜綱と六放サンゴ亜綱に大別される。ポリプ型(→ポリプ)のみで,生活史のなかでクラゲ型(→クラゲ)の時期がない。ポリプは円筒形で,上端にある口盤は触手冠(→触手)で囲まれている。外部形態は放射相称であるが,内部は左右相称形である(→相称)。石灰質や角質の外骨格または内骨格をもつものも多い。すべて海産。単体または群体で生活し,多くは他物に着生している。スナギンチャク,ハナギンチャクなど世界で約 6000種(うち日本産は約 1500種)が知られている。(→刺胞動物,無脊椎動物)
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