scyphistomas

Scyphistoma refers to the juvenile polyp stage in the life cycle of scyphozoan jellyfish, the true jellyfish. It forms after a planula larva settles on a solid substrate and metamorphoses into a small, sessile polyp that remains attached to the surface by a basal disc.

In the scyphistoma stage, the organism can reproduce asexually by budding, increasing its size or giving rise to additional polyps. Under certain environmental conditions, the scyphistoma undergoes strobilation, a developmental process in which the polyp segments into a series of transverse, saucer-like plates known as a strobila.

Each segment of the strobila eventually detaches as a free-swimming ephyra, a juvenile medusa, which grows into a mature jellyfish (the sexual stage). The scyphistoma thus serves as the polypoid phase that bridges planula settlement and the medusa stage in scyphozoan life cycles. The duration of the scyphistoma stage can vary by species and environmental factors, ranging from weeks to months or longer.

Etymology derives from Greek scyphos (cup) and stoma (mouth). The term is used specifically to describe this polyp form within the broader jellyfish developmental sequence, helping distinguish the sessile polyp from the free-swimming medusa stage.