Dr Thomas Doyle Cert. Science, BSc, PhD, a Research Fellow at the Coastal and Marine Research Centre of the Environmental Research Institute at University College Cork gave an educational talk at the 2013 Global Open Water Swimming Conference.

Among other things, he has spent time putting tags on jellyfish off the Irish Sea. “It was not an easy thing to do.”

His talk gave the educational basics of jellyfish.

There are 4 types of stinging jellyfish. The scyphozoans, the box jellyfish, the hydromedusae that have hundreds of species most smaller than 10 mm in size, and the siphonophores that look like a long frayed rope but it also includes the Portuguese man o war.

Jellyfish include a bell, the tentacles, and the oral arms, but different waters have different jellyfish. “What are the species you will find in the waters that you will encounter? This is the information that swimmers are interested in.

Jellyfish are not randomly distributed. Jellyfish are found in key places. For example, the Lion’s Mane is located in the northern parts of the Irish Sea and the compass down towards the south. And not all jellyfish form aggregations. Jellyfish species do different things. Some move up and down and some stay at the same level. And they grow over time. They are small in the winter and autumn when the jellyfish are much smaller.

There is evidence that jellyfish populations are unceasing, but there are locations where they are decreasing or are stable. The media talks about the growth of jellyfish around the world, but it is not a global phenomena. Jellyfish are a part of the marine ecosystem. They prey on things and are eaten by others.”

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