腔肠动物的一种体型.呈圆柱形，基部附于其他物体，另一端游离，周围有若干触手.简单的水螅型个体中，触手围着隆起的垂唇，垂唇中央为口，消化腔简单.有些种类体表还被复着外胚层细胞分泌的角质膜.珊瑚纲的水螅型构造较复杂，游离端称口盘，没有明显的垂唇，口盘周围有许多触手.口部外胚层陷入成口道.消化腔内有若干宽、窄不同的隔膜，最宽的隔膜，其内端和口道相连，其余隔膜内端为隔膜丝，游离于消化腔内.有的隔膜丝在消化腔底部形成游离的毒丝，含大量刺细胞，有防御和捕食功能.GOOGLE英文翻译:A coelenterate body. Was cylindrical, the base attached to other objects, the other end free, surrounded by a number of tentacles. Simple hydra-type individuals, the tentacles around the uplift of the hanging of the lips, vertical lip of the Central for the mouth, digestive cavity Simple. Some species are also re-surface of the ectodermal cells to secrete cuticle. Anthozoa of the hydra-type structure is more complex free-end, said port plate, there is no obvious vertical lips, mouth plate surrounded by a number of tentacles. mouth ectoderm caught into the Hau Road. digestive cavity a number of wide and narrow divide different, the most wide membrane, its inner end and Hau Road, connected to the rest of the inner end of the diaphragm membrane silk, divorced from digestive cavity. some wire in the digestive membranes cavity at the bottom of the formation of toxic free silk, containing a large number of stinging cells, there is defense and predatory function.