Order SEMAEOSTOMEAE L. Agassiz, 1862

Museums

Regional Maps

Introduction

Semaeostome medusae are common in Australian waters, especially along the southern temperate coasts; they are the "jellyfish-looking jellyfish", with rounded bodies, frilly hangy-down bits, and lots of hair-like tentacles; they come in an array of colours and colour patterns, warning the curious naturalist about their sting -- they do sting, though none in our waters are as dangerous as the cubozoans that are commoner in tropical waters.

Semaeostomes are easily distinguished from the other orders, i.e., the coronates and the rhizostomes. The semaeostomes lack pedalia and a coronal furrow that characterise the coronate medusae, which are primarily known from the deep sea and are often coloured deep red. The semaeostomes also have a central mouth between the four oral arms, whereas the rhizostomes lack the central mouth, instead having thousands of mouthlets along the frilly parts of the usually eight oral arms; furthermore, rhizostomes lack marignal tentacles, making them identifiable from a distance.

Diagnosis

Scyphozoa with umbrella without coronal groove and without pedalia; with or without hollow marginal tentacles; without interradial gastric septa; with radial septa in gastrovascular sinus or with gastrovascular canal system; with four simple oral arms with frilled or folded lips.

Diagnosis References

Russell, F.S. 1970. Medusae of the British Isles. II. Pelagic Scyphozoa with a Supplement to the First Volume on Hydromedusae. Cambridge : Cambridge University Press 284 pp. [70]

History of changes