(1)coelenterates typically having alternation of generations; hydroid phase is usually colonial giving rise to the medusoid phase by budding: hydras and jellyfishes
(2)一般的に世代交代のある腔腸動物
(3)ヒドロ虫の段階は通常群生で、発芽によりクラゲ状体段階を引き起こす