Scyphozoa
Scyphozoa is a class of marine cnidarians that includes most jellyfish. Its members typically have a conspicuous, free-swimming medusa stage.
Cnidaria: A phylum of aquatic animals characterized by stinging cells called cnidocytes. Scyphozoa is one of its major classes, alongside corals, sea anemones, and hydrozoans.
Metagenesis: A life cycle that alternates between distinct sexual and asexual generations. Scyphozoans commonly alternate between sexual medusae and asexual polyps.
Cyanea capillata: A large North Atlantic scyphozoan commonly called the lion’s mane jellyfish. Its long tentacles and large bell exemplify the dramatic size some scyphozoans reach.
Hydrozoa: A class of cnidarians that includes hydras, siphonophores, and many small jellyfish. Hydrozoans often emphasize the polyp stage, unlike the prominent medusae typical of scyphozoans.
Medusa (biology): A free-swimming, bell-shaped body form found in many cnidarians. This conspicuous adult form is characteristic of most scyphozoans.
Planula: A ciliated, usually free-swimming larva produced by many cnidarians. After fertilization, scyphozoan medusae typically produce planulae that settle and form polyps.
Chrysaora fuscescens: A Pacific scyphozoan commonly called the Pacific sea nettle. Its conspicuous blooms and stinging tentacles make it a familiar coastal example.
Cubozoa: A class of cnidarians known as box jellyfish, with cube-shaped medusae and complex eyes. Box jellyfish are a distinct medusa-bearing class, not members of Scyphozoa.
Polyp (biology): A sessile, tube-shaped cnidarian body form with a mouth surrounded by tentacles. Scyphozoan life cycles commonly include a polyp stage before medusae develop.
Aurelia aurita: A widespread scyphozoan commonly called the moon jellyfish. Its familiar life cycle illustrates polyp strobilation and ephyra release.