Jellyfish and Japweed at Studland

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Yesterday on Knoll Beach at Studland Bay in Dorset, the two most common things washed ashore were great clumps of Japweed (Sargassum muticum) and large barrel-mouthed or dustbin-lid jellyfish (Rhizostoma octopus). There were at least a dozen jellyfish on the stretch of sand that I walked. They varied in size from about 20 – 60 cm diameter across the dome. The colours varied from crystal clear to pink and blue. They all seemed very fresh and I think maybe some of them were still alive or just expiring. As they washed to and fro in the waves, sometimes entangled in the Japweed, they turned this way and that, upright then upside down, inside and out. This species is becoming an increasing feature on south-west coasts over the last couple of summers. I first encountered these seashore creature on the Gower Peninsula in South Wales where they have long been a frequent find on the beaches. Click here to learn more about the Rhizostoma octopus jellyfish on Jessica’s Nature Blog.

10 Replies to “Jellyfish and Japweed at Studland”

  1. Thanks for the link, Adrian. The jellyfish I saw on this occasion certainly looked very plump and well fed – apart from being dead, of course!


  2. Well, jellyfish cannot control where they swim and are at the mercy of wind, tide, and current. So it is not unusual for them to wash ashore, sometimes in large numbers. Once ashore they usually die as they can’t tolerate exposure to air. At the moment, the numbers of barrel jellyfish have been predicted to occur in England because of the weather. Adrian McGlynn has just sent me the following link which was published a few days ago – – Southampton University and the National Oceanographic Centre are not too far away along the south coast from where I found the jellyfish yesterday.


  3. My father-in-law was MOH for Llwchwr and Gower. He would get annoying phone calls at the weekend.
    “Dr, there’s a Portuguese Man-Of-War on the beach at Oxwich!. What are you going to do about it?”


  4. As I was writing the name of the barrel jellyfish on the local National Trust noticeboard for wildlife sightings at Studland, an observer commented that he had thought the jellyfish were Portuguese Man-of-War. I was able to reassure him.


  5. They seem to be an increasingly frequent phenomenon on the south coast. I believe that they are the most popular food item for leatherback turtles that follow the jellyfish swarms along the Gulf Stream and around our western coasts. I wonder if we will see more of them too?


  6. Many jellyfish on the beach at Studland sunday 21st June. Nobody swimming except in a small area seemingly protected by a net! The National Trust employees seem to be picking up the dead bodies and removing them from the beach.Many flies(unusual on Studland beach?)attracted
    by the decaying bodies.


  7. Thanks for the update Jim. looks like the jellyfish I saw were only the vanguard of the “invasion”. I have been seeing pictures in the media more recently of the huge quantities now washing ashore on the Isle of Portland and all along the coast down to Cornwall.


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