Large Numbers of Portuguese Man o' War Reported on World Jellyfish Day

portuguese man o war mcs title

The Portuguese man o' war looks like a jellyfish and stings like a jellyfish, but isn't a jellyfish (Photo: Peter Richardson/MCS)

Beachgoers in the South West of England have reported large numbers of the jellyfish-like Portuguese man o' war washing ashore to the Marine Conservation Society’s (MCS) Jellyfish Survey, just in time to mark World Jellyfish Day on 3 November.

With a transparent purple body and long, extremely powerful stinging tentacles, the Portuguese man o' war (Physalia physalis) – known as the bluebottle in Australia – closely resembles a jellyfish but is, in fact, a hydrozoan – a colony of individual organisms known as zooids that function together as a single entity. 

Sightings of the man o' war are relatively rare in the UK, however, the MCS reports a recent influx of sightings along the south-west coast of the UK. A similar event occurred in 2017, the largest reported mass stranding since 2012.

'Through our online jellyfish survey, we started receiving reports of Portuguese man o' war on beaches in South Wales in September,' said Dr Peter Richardson, Head of Ocean Recovery at the MC. 'Through October we have continued to receive reports of them from Devon and Cornwall beaches, with mass strandings in Cornwall this weekend.

'The weather will be blowing them in from the Atlantic as part of another major Portuguese Man of War stranding event,' said Richardson. 'The last stranding, in similar conditions, was in 2017 and they seem to be getting more frequent since we started our survey in 2003.

'We urge beach users not to touch them because they pack a very powerful sting,' he added, 'but please do report them on our website so we can better understand the extent of this stranding event.'

The MCS has worked closely with the University of Exeter on the Jellyfish Survey, publishing the UK distribution and seasonality of eight jellyfish and jellyfish-like species – including the man o' war – in 2014, based on the data collected from the survey. The publication represented the first time that UK jellyfish distribution had been mapped in more than 40 years, and, using the power of citizen science, the charity intends to track further changes in the jellyfish bloom over time.

'The Marine Conservation Society’s Jellyfish Survey is an incredibly helpful tool in mapping these sort of mass stranding events of jellyfish,' said Professor Brendan Godley, Chair in Conservation Science at the University of Exeter. 'Since beginning to collect information in 2003, the survey has built up a fantastic data set which helps us understand how jellyfish species react to environmental changes. Identifying where jellyfish are blooming around UK shores gives an insight into how they are reacting to the effects of climate change such as ocean warming. The current influx is, no doubt, resultant from the extremely strong winds that we have been enduring in the southwest'

For more information on the different species of jellyfish or jellyfish-like creatures that can be found on UK beaches, take a look at the MCS jellyfish guide, and to contribute to the charity's ongoing Jellyfish Survey, sightings of jellyfish (and other animals) can be reported on the website at (registration with an e-mail address required)




Love diving? You'll love these. Sign up today to immediately download our unique FREE gifts -

AROUND THE WORLD IN 80 WRECKS - DIVE's 70-page, beautifully illustrated, colour guide to the world’s best wrecks

SCUBA STORIES - DIVE's collection f real life stories where divers, who have got themselves into perilous situations, describe how they reacted and what actions they took to ensure they lived to tell the tale

PACIFICHighlights of the Pacific - Dancing mantas in Hawaii • The Best Diving in the World, Galápagos, Cocos, Malpelo & Socorro • Mass Spawning Events in Palau

New Upright Gift Banners 300 x 600 px

Sidebar SUBSCRIBE spring 21 large2

Destinations Spotlight

Need inspiration for your next dive trip? Try one of our featured destinations from DIVE's travel partners.

sidebar philippines sidebar bahamas sidebar mexico sidebar fiji sidebar st helena 2020 Sidebar Egypt sidebar banner sabah sidebar banner belize sidebar banner south africa

DIVE Partners

sidebar banner egypt new ceningan divers ad 300x100 LH 300 min giphy subex Wakatobi Siladen Aggressor Fisheye Dive Worldwide gozo banner Arenui

Read DIVE magazine

DIVE magazine is available to read on many devices. Simply click one one of the options below

PCMac final
Apple finalAndroid final

Like what you see?

Join us on social and keep updated daily...