Scyphozoa
Quick Summary
Scyphozoa is a class of invertebrate marine animals within the phylum Cnidaria, commonly known as true jellyfish. These animals are characterized by their radial symmetry and a body composed of two cell layers with a gelatinous mesoglea in between.12
Scyphozoans typically have two distinct body forms in their life cycle: a sessile polyp stage (scyphistoma) and a free-swimming medusa stage (jellyfish). The polyp stage asexually buds off young medusae called ephyrae, which grow into adult jellyfish. Adult jellyfish reproduce sexually, with gametes developing in gonads. Fertilized eggs develop into a planula larva, which attaches to a surface and transforms into a new scyphistoma, completing the cycle.31
While most scyphozoans have both polyp and medusa stages, some species, like those in the order Stauromedusae, are sessile and lack a free-swimming medusa stage. The medusa form is generally larger and more conspicuous than the polyp form in scyphozoans.12
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