Blue Jellyfish (Cyanea lamarckii)
The blue jellyfish is found as far away as Japan and Australia, but in Britain its distribution is limited to off the coast of the south west and Wales, with sightings elsewhere in the UK being rare. They can be up to 30cm across, but are typically half this size. It has a thicker umbrella than the common jellyfish, and is often a dark blue in colour. It has a mass of tentacles trailing below it, many of which have stinging cells present.
Barrel Jellyfish (Rhizostoma pulmo)
Also known as the dustbin-lid jellyfish, this species is found mostly around the west and south coasts of the British Isles, although they can also show up around the Welsh coast and elsewhere in around the UK from time to time. They are also found throughout European waters, especially in the Mediterranean. They are a large jellyfish species, reaching up to a metre across in exceptional specimens, although they are usually half this size in British waters. The usual colour is white to pale yellow. This species of jellyfish is easily identified by its domed bell upper section and trailing tentacles, the upper portions of which are often referred to as resembling the appearance of cauliflower. The barrel jellyfish feeds by catching plankton and microscopic mid-water crustaceans in its tentacles as it floats through the water. Like most jellyfish species the barrel jellyfish is much more likely to be found in British waters in the warmer months of the year.
Compass Jellyfish (Chrysaora hysoscella)
The compass jellyfish is widely found throughout European and African waters and can be found around the south and west parts of the United Kingdom in the summer months. It is only an occasional visitor elsewhere in Britain. It is usually described as having a saucer shaped bell (body) which is usually pale yellow to light brown in colour with darker lines running from the centre point to the edges. These lines look like the markings on a compass which is how this species gets its name. The size of this jellyfish is usually 15 to 20cm across, although they can reach 30cm in some specimens. The long tentacles which trail behind this species contain potent stinging cells which can cause considerable pain if they come into contact with human skin. The compass jellyfish feeds by using its tentacles to catch tiny mid-water crustaceans and plankton.
Comb Jelly (Beroe cucumis)
The comb jelly has an oval shaped body which is up to 15 to 18cm in length. The body appears transparent with the rows of cilia (which provide motion) more visible, showing iridescent colours when the comb jelly uses them to move. This species lives in midwater and feeds on smaller comb jellies and other jellyfish species. Their mouth opens wide to consume these creatures whole. They are mostly found around the western coast of the British Isles, but have been recorded in the North Sea and English Channel as well.