Jellyfish Sightings on Dorset Beaches

Barrel jellyfish by Peter Tinsley Barrel jellyfish by Emma Rance Compass jellyfish by Paul Naylor Compass jellyfish by Emma Rance Moon jellyfish by Paul Naylor RS15235 Moon jellyfish by Emma Rance-lpr Blue jellyfish by Peter Tinsley Blue jellyfish (Cyanea lamarckii) by Emma Rance Portuguese man o war by SARAH HODGSON

Eight jellyfish species have been recorded throughout Dorset with frequent sightings of the compass, moon, blue and barrel jellyfish in the spring and summer.  On occasion, these have included swarms.  

The barrel jellyfish is one of the largest we see in Dorset.  Odd sightings of these have occured over the last few decades but this changed in May 2014, when swarms appeared along the South Coast. Similar numbers have been reported throughout spring and summer 2015. 

Barrel Jellyfish, which grow up to an impressive 1 metre wide and weigh 25kg, can give a mild sting, even when dead.  Dorset Wildlife Trust (DWT) is advising members of the public not to touch any jellyfish they find and to send in photos of the sighting.  These are are essential to aid identification particularly as jellyfish change colour, shape and size when stranded.  (See the slideshow above or CLICK HERE for a downloadable guide)

Conditions are just right for jellyfish to feed along the coast of Dorset

Most jellyfish are seen inshore during the spring and summer.  During April, longer sunny days, warmer sea temperatures and an upwelling of the nutrients from the depth of the water column, create an increase of microscopic plants and animals, known as the spring plankton bloom.   This fabulous food source is the main diet for many marine species and this bloom, along with a mild winter, creates the perfect conditions for jellyfish to flourish.  

Jellyfish swarms could entice more marine life

The leatherback turtle and the oceanic sunfish have been known to visit Dorset.  Whilst confirmed sightings of the leatherback are uncommon, sunfish are often reported in the summer.  Both of these species are attracted to the South Coast in pursuit of their favourite food.  An increase in jellyfish numbers is likely to improve the chance of seeing these impressive megafauna and averaging at 2m in length, that would be quite a sighting.  Keep your eyes peeled!

A video of a Barrel Jellyfish at Worbarrow Bay by Clifford Baxter


If you see anything interesting please let us know

Dorset Wildlife Trust encourages members of the public to record what they find along the beaches and shallow shorelines in Dorset including jellyfish, so if you see anything interesting, please let us know.  You can also post your photos on the DWT Facebook page at and twitter page @dorsetwildlife or email

Treatment of Jellyfish Stings

Please remember to look but don't touch - jellyfish are capable of stinging even when stranded dead on the shore.  Remember to keep dogs away too.  Some species such as the Portuguese man o'war are known to cause a painful sting but are rarely deadly. 

If you have been stung by a jellyfish, seek medical advice!  The NHS provide full details on the prevention, symptoms and treatment of a jellyfish sting HERE.


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