Now the warmer weather is here jellyfish will start heading nearer the beach. Kate Wilson from the Marine Conservation Society describes 7 to look out for and which ones have the deadliest stings...
Moon jellyfish (Aurelia aurita)
This transparent, jellyfish grows up to 40cm in diameter and can be recognised by the four pale purple gonad rings in the centre. The bell is umbrella-shaped, with short hair-like tentacles around the edge. This jellyfish has a mild sting.
Compass jellyfish (Chrysaora hysoscella)
The compass jellyfish comes in varied shades of brown with diagnostic brownish V-shaped markings on the bell. They typically grow up to 30cm, and have 24 long, thin tentacles and four long, thick, frilled arms. This jellyfish stings!
Blue jellyfish (Cyanea lamarckii)
This has a similar shape to the lion’s mane jellyfish, but it is much smaller, growing up to 30cm. The bell is usually a striking blue colour through which thin, radial lines can be seen. Confusingly, some specimens of blue jellyfish are a yellowish straw colour. This jellyfish has a mild sting.
Barrel jellyfish (Rhizostoma octopus)
These large jellies grow up to a metre wide and have a mild sting. They have a rounded, solid, rubbery bell, which can be white, pale pink, blue or yellow and is fringed with purple markings. The bell lacks tentacles but it has eight thick, frilled arms.
Mauve stinger (Pelagia noctiluca)
This smaller jellyfish grows up to 10cm and has a deep bell with characteristic pink or mauve ‘warts’. It has eight, hair-like tentacles and four longer frilled arms with tiny pink spots. This jellyfish stings!
Portuguese Man-of-War (Physalia physalis)
The Portuguese-Man-of-War is not a jellyfish at all! It is a floating colony of hydrozoans. Although rare in the UK, it should be reported to the local authorities if found stranded in numbers as it can be dangerous to humans due to its powerful sting. It’s characteristic crested, blue-purple float with long blue stinging tentacles hanging below make this animal easy to recognise.
By-the-wind-sailor (Velella velella)
Not a jellyfish but a floating, solitary hydranth occurring in swarms. It grows up to 10cm long and is blue-purple in colour. It has a diagnostic upright sail and float, with a mass of small tentacles surrounding the mouth on the underside and can occur in vast swarms.
While some jellyfish are harmless or have a very mild sting, others have a painful and even dangerous sting. MCS recommends that, for your own safety, you do not touch jellyfish, and advise seeking medical attention in the case of a severe sting, You can find some great advice from the Red Cross here
You can help the MCS find out more about jellyfish in UK waters by taking part in the Marine Conservation Society’s Jellyfish Survey! Simply report your sightings to MCS
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