Fossilized stranded scyphozoans on a Cambrian tidal flat at Blackberry Hill, Wisconsin. The Scyphozoa are an exclusively marine class of the phylum Cnidaria, [2] referred to as the true jellyfish (or "true jellies").

scyphistoma /saɪˈfɪstəmə/ 1.N a sessile hydra-like individual representing the polyp stage of scyphozoans. It produces forms which become free-swimming jellyfish 钵口幼体 [1]

A sessile polyp (scyphistoma) stage asexually buds off young medusae from its upper end, with each such ephyra growing into an adult. The adults are either male or female, but in some species they change their sex as they age.

The planula metamorphoses into a sessile (i.e. fixed-position), usually benthic (i.e. bottom dwelling) polyp called a 'scyphistoma' and it is the scyphistoma, still attached to the surface on which the planula settled, that produces a new free-swimming medusa.

Under suitable environmental conditions, scyphistomae undergo transverse segmentation and segment metamorphosis (strobilation). The segmented parts of the strobilating polyp (strobila) develop into incipient medusae that eventually break loose and become free swimming young jellyfishes (ephyrae).

钵水母纲（学名：Scyphozoa）是刺胞动物门的一个纲。 例如水母、海蜇、 海月水母 、霞水母等。 这类水母早在 寒武纪 就已出现，直到现在。 全海产，多为大型的水母。 大部分种类有世代交替现象。 水母型不具缘膜，结构复杂，感觉器官为触手囊； 水螅型 不发达甚至消失，常常以幼虫的形式出现。 生殖腺由内胚层产生。 内 外胚层 均有刺细胞。 水母纲隶属刺胞动物门，全部海产。 生活史主要阶段是单体水母。 均营 浮游生活，广布于各大洋，尤以热带海区为多。 钵水母的 …

scyphistoma a larval form of a COELENTERATE, arising from a planula larva, which may bud, but in autumn and winter produces EPHYRA larva by STROBILATION. see SCYPHOZOAN.

由生殖腺产生精子或卵（钵水母为雌雄异体），精子成熟后随水流至雌体内受精，也有的在海水中受精，受精卵经完全均等卵裂形成囊胚，再由内陷方式形成原肠胚，此时胚胎表面长出纤毛，成为浮浪幼虫，在海水中游动一个时期后，附于海藻或其他物体上 ...

A larva metamorphoses into a small polyp termed the scyphistoma. Scyphistomae commonly produce more scyphistomae asexually. Eventually, a scyphistoma becomes a strobila, in which the distal end develops into a medusa-like animal.

2024年11月23日 · Class Scyphozoa, an exclusively marine class of animals with about 200 known species, includes all the jellies. The defining characteristic of this class is that the medusa is the prominent stage in the life cycle, although there is a polyp stage present.