Wales Beach Guide

A Quick Guide to Jellyfish

Jellyfish are commonly seen washed up on the beaches during the summer months, but fortunately in Wales, most are relatively harmless and stings can be easily treated. The sting is caused by specialized cells called nematocysts, which are triggered by contact, and inject venom into the victim. If stung, the current advice is to remove any remaining stinging cells with tweezers, or gently scrape the affected area with a straight edge (e.g. a credit card). It is now thought that the old treatment of applying vinegar (even if you had some) is ineffective. In the unlikely event of suffering an allergic reaction, get to hospital quickly!

Jellyfish typically have a lifespan of just a few months, and are made up of around 90% water.

Moon Jellyfish

Moon Jellyfish

These are the most common jellyfish around the coasts of Wales, and have only a mild sting. They can be identified by the four pink or purple rings and can reach up to a foot in diameter.
Found at : Porth Dynion
Barrel Jellyfish

Barrel Jellyfish

These can be up to 3 feet across, and only have a very mild sting. Occasionally they are washed ashore in their thousands, but are not a danger to swimmers.
Found at : Pembrey Beach
Blue Jellyfish

Blue Jellyfish

This is a stinging species and can be up to 12 inches across. Easily identified by their colour.
By-the-wind Sailor

By-the-wind Sailor

These have an oval deep blue body about 2 to 3 inches wide, with a vertical triangular vane on top. They float on the water, rater than in it, are not true jellyfish, and have a mild sting. Frequently washed ashore in their thousands.
Lions Mane

Lion's Mane Jellyfish

These are easily identified by their orange or rust-brown colour, and can deliver a painful sting. Welsh specimens are usually 12 - 20 inches wide, and it's more common in North rather than South Wales.
Found at : Llanfairfechan
Compass Jellyfish

Compass Jellyfish

This is a stinging species, and can grow up to a foot in diameter. Easily identified by its brown Y-shaped markings.
Found at : Llanfairfechan
Portuguese man-o-war

Portuguese man-o-war

Not a jellyfish, but a siphonophore - a colony of individuals dependent upon each other. The float is pink to purple in colour, up to 10 inches long and tentacles may reach several yards in length. Can inflict a serious sting. Once a rare visitor, but becoming more common.
Found at : Freshwater West
Sea Gooseberry

Sea Gooseberry

These are ctenophores, not true jellyfish and are often washed up along the tideline. They are about an inch long with two branches of comb-like tentacles, and are harmless. Underwater, their transparent bodies can refract light into its different colours.
Found at : Aberavon Sands