|Researched by||Marisa Sabatini||Refereed by||Admin|
|Other common names||-||Synonyms||-|
Rhizostoma pulmo has a solid appearance. It varies in colour from whitish pale or yellow to shades of green, blue, pink or brown. The umbrella margin is divided into a number of semi-circular lobe like extensions (marginal velar lappets). Beneath the bell is a large manubrium, consisting of a short pillar-like basal stem, followed by sixteen, three winged epaulets with frilled mouth openings. It then divides into four pairs of oral arms that consist of three winged portions, followed by three winged elongated terminal appendages (Russell, 1970). Mature males have blue gonads whereas, ripe females are reddish brown. When exposed to air their nematocyst warts give the umbrella surface a matt like appearance. The large crustacean Hyperia galba can be found throughout the body of the jellyfish and more commonly in its gastric or gonad pouches.
This species was previously been known as Rhizostoma octopus which was regarded by some authors as a variety of Rhizostoma pulmo rather than a distinct species (Russell, 1970). Russell (1970) stated that the only valid character by which they could be distinguished was by examining the number of velar lappets on the umbrella margin. However, Rhizostoma pulmo is now the accepted name.
It is sporadic in occurrence from year to year but occurs in 'swarms' in summer and autumn. It is believed that some specimens probably live in deep water during winter.
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Fish, J.D. & Fish, S., 1996. A student's guide to the seashore. Cambridge: Cambridge University Press.
Hayward, P., Nelson-Smith, T. & Shields, C. 1996. Collins pocket guide. Sea shore of Britain and northern Europe. London: HarperCollins.
National Biodiversity Network (NBN) Atlas website. Available from: http://www.nbnatlas.org. Accessed 01 April 2017
O'Connor, B. & McGrath, D., 1978. The occurrence of the scyphozoan Rhizostoma octopus (L.) around the Irish coast in 1976. Irish Naturalists' Journal, 19, 261-263.
Russell, F.S., 1970. The medusae of the British Isles. Vol II - Pelagic Scyphozoa, with a supplement to the first volume on hydromedusae. Cambridge University Press
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Last Updated: 18/03/2004