From a distance, from a very long way off, it might have been possible to mistake this piece of unusual flotsam for one of the many blue jellyfish that drift ashore at Rhossil Bay in Gower. Actually, just an inflated blue rubber glove – don’t ask me what it was doing there. Some of the things you find as flotsam on British beaches are intriguing.
This picture shows what the real blue jellyfish looks like. You can see why someone might have thought the glove was one. Only this animal is very much bigger than the flotsam. The diameter of the dome can measure upto 90 cm across. This is the Dustbin-lid Jellyfish, Rhizostoma octopus (Linnaeus), also apparently called a Barrel or Root-mouthed Jellyfish.
The colour of these jellyfish is variable. You can compare this specimen from Rhossili – with the top of the blue dome being uppermost and the oral arms just protruding from the dome or bell – with the specimen featured earlier in Monster jellyfish stranded on Whiteford Sands which was stretched out with the underside (sub-umbrella or oral surface) and oral arms entirely visible. There’s also more information and pictures in the post Pink Dustbin-lid Jellyfish at Rhossili.
The picture below shows one of a yet another colour variation drifting ashore in shallow water with the incoming tide at Rhossili. Unlike many jellyfish, this type does not have a ring of dangerous stinging tentacles around the outer edge of the large dome or umbrella. However, the upper surface of the umbrella (known as the ex-umbrella or aboral surface) is covered with groups of tiny nematocysts or stinging cells that give a slightly matt appearance to the surface when it is out of water.
Revision of a post first published 11 July 2009
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