Types of jellyfish most commonly found in UK waters.

Pic: ABC News

Spend enough time at coastal waters and you’re bound to come across jellyfish. Spend enough time at coastal venues and you’re also likely to see unaccustomed swimmers/bathers and water users running for the hills when jellyfish come into the vicinity.

We all know that jellyfish sting, right? And stories of deadly species are widely told. So should we be legging it to momma whilst screaming when jellyfish pop up? Here’re the most common types of jellyfish found in UK waters and how harmful they are. It should be noted that all jellyfish can sting to some degree but not all are painful and hazardous to life. Allergic reactions can occur, however, with any kind of toxin entering the body.

Moon jellyfish

Identified by their four white rings the Moon jellyfish can congregate in mass blooms. Their stings, however, don’t get through human skin so aren’t that harmful.

Lion’s mane jellyfish

This species of jellyfish can grow to colossal sizes. The Lion’s mane jellyfish is recorded as the second longest animal in the world with tentacles that stretch for quite away. These are defined by their orange colour and if they sting you then temporary pain and redness can occur. If you come a cropper with Lion’s mane jellyfish seeking medical help is advised. LM tentacles can also become separated during storms and remain live. Floating on the surface of water or washed onto beaches they’re quite hard to see.

Barrel jellyfish

This type has a very weak sting and can be found in large numbers. They can grow quite big and usually inhabit harbour waters. Barrel jellyfish don’t have long trailing tentacles but their purple fringe can cause alarm in water users who don’t know.

Compass jellyfish

With a sting that feels like brushing against nettles the Compass jellyfish gets its name because of compass like markings on its body. The Compass can often be found washed up on beaches – especially after storms or following high surf.

Mauve jellyfish

The Mauve jellyfish is probably the one to watch out for most as its sting can lead to a burning sensation, blisters, scabs and nausea. Some symptoms can be more severe so medical attention should be sought. Its purple body can often appear to glow so is therefore very distinct.

Blue jellyfish

Blue jellyfish aren’t quite as common as some other species but are very unusual almost resembling some kind of floating Christmas decoration. Whilst they do sting it’s a mild one that feels like brushing against nettles.

Portuguese man ‘o war

Occasionally Portuguese man o’ war do end up in UK waters and wash up on beaches. Its stinging venom paralyses small fish and other prey by wrapping tentacles that cling to its victim. This has been known to happen to young children leading to severe consequences. The man o’ war differs from other jellyfish in that it’s a multi-organism animal made up of genetically distinct zooids. The connected zooids join together to function as one animal. Stings from man o’ war are very painful and resemble welts caused by a whip.

A Man-O-War jellyfish floats in the Atlantic Ocean.