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 www.mcsuk.org/sightings/report/jellyfish (registration with an e-mail address required)

 

 

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