Portuguese man o' war

Portuguese man o' war ©Matt Slater Cornwall Wildlife Trust

Portuguese Man O'War

Scientific name: Physalia physalis
Despite appearances, this weird and wonderful creature is not a jellyfish! They're sometimes found washed up on our shores after westerly winds. Look but don't touch - they give a very nasty sting.

Species information

Statistics

Float Length: Up to 30cm Tentacle Length: 10-20m

Conservation status

Common across their range, rare on UK shores

When to see

September to December

About

First of all, the Portuguese Man O'War is not a jellyfish. It is a colonial hydrozoan, made up of small individual animals called zooids - each with their own specific function, e.g. feeding or breeding. They can't live separately and function together as one "animal". Cool, hey? The Potuguese Man O'War lives at the surface of the open ocean, held afloat by a gas-filled bladder. This has a crest like structure at the top which acts as a sail. They can't swim and are at the mercy of the winds - which is why they often end up washed ashore after big storms. They are fearsome predators, catching small fish and crustaceans with their long stinging tentacles. It's these tentacles that you need to watch out for too - they can sting long after the animal has died. Portuguese Man O'War are the favourite food of the Violet Sea Snail - a weird floating sea snail that builds its own bubble raft in order to remain at the surface and hunt its prey.

How to identify

Unmistakeable! A large translucent purple float, the crest tipped with pink, and long blueish-violet tentacles. The float is seen bobbing on the surface of the sea, sometimes caught in mats of seaweed. They lose their colour quickly after stranding and can appear translucent with just a tinge of purple after a while ashore.

Distribution

A pelagic (open ocean) species. Blown into UK seas on westerly winds and washed ashore on the West Coast of the UK. Mainly Isles of Scilly and Cornwall, but increasingly West and North Wales and as far north as Cumbria.

Did you know?

The Portuguese Man O'War is named after the 18th Century armed sailing ship - as its believed they look like one at full sail. Its other name is Floating Terror!

How people can help

Report any sightings of Portuguese Man O'War to your local Wildlife Trust. Look but don't touch - they give a very nasty sting, even long after they are dead. The Wildlife Trusts are working with sea users, scientists, politicians and local people towards a vision of 'Living Seas', where marine wildlife thrives. Do your bit for our Living Seas by supporting your local Wildlife Trust or checking out our Action Pages.