Knowra Jellyfish Jellyfish Jellyfish are gelatinous marine animals with umbrella-shaped bodies and tentacles bearing stinging cells. Most belong to the subphylum Medusozoa and drift or swim through the water.
Cnidocyte : A specialized stinging cell found in cnidarians, used to capture prey or deter predators. Jellyfish tentacles carry these cells, which discharge microscopic harpoons on contact.
Cnidaria : A phylum of aquatic animals characterized by cnidocytes, including jellyfish, corals, sea anemones, and hydroids. Jellyfish are members of this phylum, whose stinging cells define their closest biological kin.
Jellyfish sting : A skin injury caused when jellyfish stinging cells discharge venom-delivering threads. Stings are the most direct human encounter with jellyfish and vary greatly in severity.
Lion's mane jellyfish : A large cold-water jellyfish with a broad bell and long, trailing tentacles. It illustrates how far jellyfish size and tentacle length can exceed familiar coastal species.
Nematocyst : A pressurized capsule inside a cnidocyte that ejects a coiled, often venomous thread. This capsule delivers the sting that makes jellyfish effective predators.
Medusozoa : A cnidarian subphylum whose members commonly have a free-swimming medusa stage. Most animals commonly called jellyfish belong to this medusa-bearing group.
Irukandji syndrome : A severe systemic illness caused by stings from certain small box jellyfish. This syndrome shows how some jellyfish venoms can cause effects beyond the sting site.
Moon jelly : A translucent, saucer-shaped jellyfish common in coastal waters worldwide. Its conspicuous four horseshoe-shaped gonads make it a widely recognized example.
Medusa (biology) : The free-swimming, umbrella-shaped body form in the life cycles of many cnidarians. The jellyfish body is the medusa form, typically propelled by rhythmic contractions.
Scyphozoa : A class of cnidarians that includes many familiar, large marine jellyfish. Its species include the classic jellyfish form most often meant by the name.
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