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If you go to any beach around Ireland during the summer months, you are undoubtedly going to encounter something that is transparent, squishy, slimy or gooey depending on your point of view. From a young age you are aware of their notoriety as something to beware of and even fear. Who are these formidable seasonal visitors and why do they make us so squeamish and reluctant to enjoy a cool dip in the summer sea?
Jellyfish don’t have bones, blood, a brain or a heart as we know it. So how do they function? This is what makes jellyfish marvellous creatures! Although they look like they should be in a horror movie, if you can get past the gelatinous body and stinging tentacles you’ll find that jellyfish are fascinating.
To start with, jellyfish aren’t fish they are actually plankton (small life forms that travel around with the water). They can range in size from less then an inch all the way up to over 100 feet!
Where do they come from?
The animal we know as a jellyfish is actually just its adult form called the medusa, named after the mythological creature that had snakes for hair.
Jellyfish have a complex life cycle.
Jellyfish babies are microscopic little larvae that soon attach themselves to a rock or surface and become polyps, now looking like a tiny stack of saucers. These polyps can spend several years like this.
When they are an adequate size they then start to break off. The polyps go through a process called budding. It is at this stage that the polyp becomes the medusa jellyfish form.
Jellyfish reproduce both asexually (alone, without a mate) and sexually (each adult jellyfish is either male or female). Generally the coloured bits of the jellyfish are the gonads (reproductive organs).
The science-y bit…
Jellyfish belong to a large group of animals known as Cnidarians (the ‘C’ is silent) which also include hydroids, anemones and corals. The name ‘cnidaria’ comes from the Greek word "cnidos," which means stinging nettle. Jellyfish are very simple in design, composed of the top part called the ‘bell’ which contains the mouth, stomach and reproductive organs, and from here extends the feeding arms and stinging tentacles. The stinging cells are called nematocysts and are like microscopic darts that shoot out when they come into contact with an object.
What types of jellyfish are here in Ireland?
While we do get some visitors from time to time like the Portuguese Man-o-War, there are over a dozen species common to Irish waters all with varying intensities of sting. Several of these species are spotted every year around the Dingle Peninsula alone. The most common species that you will recognise are the Common (Moon) Jellyfish (small with 4 purple/pink rings) and the Compass Jellyfish (larger with reddish-brown v-shaped marks and spots). The former has a very mild sting at most whereas the latter’s sting is in fact compared to that of a nettle. They don’t really seem so scary now, do they?
So why do they sting?
Jellyfish don’t mean to hurt us and not all of them sting. The problem with jellyfish is they don’t really swim, but float gently with the water current using the bell to create little waves to steer with. They are interested in smaller animals to eat than us as their tentacles are the only way of catching food. We just sometimes get in the way!
A jellyfish that’s not a jellyfish?
Anyone unfamiliar with the biology of the venomous Portuguese Man-o-War would likely mistake it for a jellyfish. Not only is it not a jellyfish, it's not even an "it," but a "they." The Portuguese Man-o-War is a siphonophore, an animal made up of a colony of organisms working together. It’s not even Portuguese! It gets its name from a 16th century warship which it resembles with its sail-like balloon. The Portuguese Man-O-War was last reported in Kerry on Wine Strand in Smerwick Harbour in 2011. They have also been reported this year around the south coast of Ireland, with a young girl just recently suffering a severe allergic reaction to the sting and having to be rushed to hospital. So although most the jellyfish here in Ireland only cause discomfort, it is very important to watch out for more severe stingers or allergic reactions.
So what if you’ve been stung?
Contrary to belief, urinating on the sting won’t help! So that saves you or somebody else some embarrassment.
Vinegar won’t help either.
Don’t use freshwater as this will only release more stinging cells.
The best thing for jellyfish stings is actually cold saltwater. It may not be what you want to do but going back into the sea is the best way to relieve the pain.
Irish Water Safety are recommending that if you have been stung by the Portuguese man of War that has been sited in Ireland recently then hot salt water should be applied to the area.
So, follow the below steps if you have been stung:
1. Ensure you don't get stung yourself when aiding others
2. Remove any attached tentacles with a gloved hand, stick, or towel (none of these available- use the tips of your fingers)
3. Do not rub the affected area (this may result in further venom release)
4. Rinse the affected area with sea-water (do not use fresh water, vinegar, alcohol or urine)
5. Apply a ‘dry cold pack’ to the area (i.e. place a cold pack or ice inside a plastic bag and then wrap this package in a t-shirt or other piece of cloth)
6. Seek medical attention if there is anything other than minor discomfort.
7. If the patient is suffering from swelling, breathing difficulties, palpitation or chest tightness then transfer to the nearest emergency department urgently.
These guidelines were drawn up by the Jellyfish Action Group of Ireland and Wales (which includes experts form Beaumont Poison Centre, Pre-hospital Emergency Care experts, hospital A&E consultants, local GPs, and water safety officers) and are only to be applied in Irish and Welsh waters. If travelling abroad seek advice for that specific country. For more information on jellyfish visit www.jellyfish.ie
For more information on treatment of Jellyfish stings please go to Irish water Safety website. Or if you’re just curious about these fascinating animals or want to record a sighting then please visit www.jellyfish.ie.