scyphistoma

Scyphistoma is the polyp stage in the life cycle of true jellyfish (Scyphozoa). It develops from a planula larva after fertilization and remains sessile, typically attaching to a firm substrate such as rocks, shells, algae, or artificial surfaces. The body is an elongated gastrovascular cavity with tentacles around the oral end, and the polyp is capable of asexual reproduction by budding, increasing in size or forming colonies.

In development and reproduction, the scyphistoma serves as the asexually reproducing stage. Through budding or fragmentation, it can persist for extended periods and contribute to population growth. In many species, the scyphistoma undergoes strobilation, a process of transverse segmentation that creates a chain-like arrangement called the strobila. Each segment of the strobila can give rise to a juvenile medusa, or ephyra, which detaches as a free-swimming young jellyfish and eventually matures into an adult medusa.

Ecology and life cycle significance vary with species and environmental conditions. Temperature, food availability, and substrate type influence the timing and extent of strobilation. The scyphistoma stage provides persistence during unfavorable conditions and serves as the source of medusae when circumstances improve, enabling dispersal and genetic exchange in marine ecosystems.

In scientific study, scyphistomae are examined to understand cnidarian development, metamorphosis, and life cycle plasticity. They also offer insight into how environmental factors shape the transition from polyp to medusa in jellyfish.