Stauromedusae

(invertebrate zoology) An order of the class Scyphozoa in which the medusa is composed of a cuplike bell called a calyx and a stem that terminates in a pedal disk.

An order of the class Scyphozoa, usually found in circumpolar regions. The egg develops into a planula which can only creep since it lacks cilia. The planula changes into a polyp that metamorphoses directly into a combined polyp and medusa form. The medusa is composed of a cuplike bell called a calyx (medusan part) and a stem or stalk (polyp part) which terminates in a pedal disk (see illustration). The calyx is eight-sided and has eight groups of short, capped tentacles and eight sensory bodies, called anchors, on its margin. The mouth, situated at the center of the calyx, has four thin lips and leads to the stomach in which gastral filaments are arranged in a row on either side of each interradius. Though sessile, the medusa can move in a leechlike fashion by alternate attachment and release of the pedal disk, using the substratum as an anchor. See also Scyphozoa.

Stauromedusae. (a) Lucernaria. (b) Haliclystus. (After L. H. Hyman, The Invertebrates, vol. 1, McGraw-Hill, 1940)

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Stalked jellyfishes
Stauromeduse from Ernst Haeckel's 1904 Kunstformen der Natur
Scientific classification
Kingdom: Animalia Phylum: Cnidaria Class: Scyphozoa Order: Stauromedusae Haeckel, 1879
Families
Cleistocarpidae Eleutherocarpidae Kyopodidae Tesseranthidae

Stauromedusae, or the stalked jellyfishes, is an order of jellyfish within the phylum Cnidaria. They are unique in that they do not enter the medusa stage, instead remaining polyps throughout their lives. After the larvae crawl across the sea floor and find a suitable place, they attach themselves typically to rock or algae to develop. Unlike most 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 studies suggest that stauromedusae should be elevated to a taxon equivalent of Scyphozoa and Cubozoa, and should therefore be know as the class Staurozoa.

References

• Introduction to Stauromedusae
• Jellyzone
• Brief classification University of Michigan
• List of all known species of Stauromedusae

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