Stalked jellyfish
| Stalked jellyfishes Temporal range: Latest Precambrian—Recent |
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| Stauromeduse from Ernst Haeckel's 1904 Kunstformen der Natur | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Staurozoa |
| Order: |
Stauromedusae Haeckel, 1879 |
| Suborders | |
Stauromedusae are the stalked jellyfishes. They are the sole living members of the class Staurozoa, and belong to the medusozoa subphylum of Cnidaria. They are unique among medusa jellyfish in that they do not have an alternation of polyp and medusa life cycle phases but are instead interpreted as an attached medusa stage, with a life style more resembling that of polypoid forms. They have a generally trumpet-shaped body, oriented upside-down in comparison with other jellyfish, with the tentacles projecting upwards, and the stalk located in the centre of the umbrella.
Members of this class are commonly found in relatively cold waters, close to the shoreline. Sexually mature stauromedusae free-spawn eggs or sperm, which fertilize in the sea and form a creeping, unciliated planula larva. The larvae crawl across the sea floor and find a suitable place, attaching themselves typically to rock or algae, where they eventually develop into a new, attached stauromedusa. Unlike most scyphozoan jellyfish that practice strobilation, or the process of dividing themselves into body segments, which become new individuals, nearly all stauromedusae develop directly into the adult form.
Although conventionally considered to be an order in the class Scyphozoa, recent genetic studies suggest that Stauromedusae should be elevated to a taxon equivalent of Scyphozoa and Cubozoa, and should therefore be known as the class Staurozoa.
Haliclystus stejnegeri
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