Jellyfish: Tips on avoiding them and what to do if you're stung

A jellyfish sting can ruin a day at the beach. Ella Walker explains how we can comfortably share our shores with the wibbly-wobbly species

A giant blue jellyfish washed up on a beach – jellyfish are a common sight on Irish beaches
Ella Walker

IF you've spent a fair amount of time on Ireland's many wonderful beaches, chances are you've encountered a jellyfish at some point or other (hopefully that means spotting it from a comfortable distance, not being stung by one).

With many families continuing to head for the coast this month, on day trips and staycations, what exactly are jellyfish, and what should you do if you come across one while swimming, or strolling along the sand?

What are they?

Shaped somewhat like mushrooms, jellyfish are generally translucent sea creatures that bob along in the water – known as 'free-swimming' – with tentacles that can be covered in poisonous sacs called nematocysts.

Different types of jellyfish

According to The Marine Biological Association, there are more than 200 species of 'true' jellyfish (there are other marine creatures that can resemble them but aren't actual jellyfish) globally, but only six species are commonly found in Irish waters.

They are:

1. Moon jellyfish (Aurelia aurita) – it has four white rings you can see through its umbrella.

2. Compass jellyfish (Chrysaora hysoscella) – has dark 'compass' markings on its umbrella.

3. Lion's mane jellyfish (Cyanea capillata) – the second longest recorded animal in the world (it can grow up to 30m), it has red and orange tentacles in bunches.

4. Dustbin-lid, or barrel, jellyfish (Rhizostoma pulmo) – these can grow up to 90cm across.

5. Blue jellyfish (Cyanea lamarckii) – as its name suggests, this guy is bright blue.

6. Mauve stinger (Pelagia noctiluca) – these sting and are capable of bioluminescence (creating its own light). However, they are an oceanic species and only occasionally make an appearance in our coastal waters.

What to do in the water

Jellyfish – although some can provide their own momentum – are generally at the mercy of the current, hence they often get washed up. Being vigilant, especially in warm shallow waters which they love, is your best bet for avoiding a nasty sting. If you do spot a jellyfish floating along, don't try and move it or wave it away, just move out of its path and alert others to its presence. If there are large numbers that are hard to avoid, get out of the water and, if the beach you're on has a lifeguard, let them know. Often lifeguards put up flags if there's a significant jellyfish population nearby. Alternatively, wear a full body wetsuit or protective waterproof footwear.

What to do on land

Look out for flags announcing whether large numbers of jellyfish have been spotted, and watch your feet in the shallows and along the tide line. This is where jellyfish tend to congregate and get stranded on the sand. While many don't sting, some do, and they can be unpleasantly slimy to step on anyway! If you're taking the dog for a walk, best to stop them nibbling or rolling in dead jellyfish too.

Moon jellyfish (Aurelia aurita) may well sting but they are extremely beautiful when seen in their natural environment

If you get stung... 

If you do get stung, get out of the water immediately and have someone remove any attached tentacles with a pair of tweezers. Apply a heat pad or run the sting under hot water – it'll help with the pain. Antihistamines can help relieve swelling, while paracetamol can help with any residual pain. Usually, aside from sore, you'll be absolutely fine – but, as with anything, seek medical help immediately if you show signs of a severe allergic reaction or become short of breath.

And don't listen to anyone who says the sting needs to be weed on – it's not true!

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