Top 5 types of jellyfish to watch out for in Ireland (and how to treat stings)

Mysterious and majestic, beautiful yet foreboding, there are many jellyfish species in Ireland.

Check out our list of the five types of jellyfish to watch out for in Ireland.

Here are five types of jellyfish to watch out for in Ireland.

There are plenty of jellyfish species in Ireland to watch out for.

Jellyfish are magnificent, strange, and sometimes surreal. The term jellyfish refers to the group of mainly free-swimming marine creatures, although – unbeknownst to many – some are attached to the seabed by stalks, limiting their movement.

Consisting of an umbrella-shaped hood and trailing tentacles, jellyfish can be hypnotic to watch. However, they are more commonly associated with their stings, which are transmitted by their tentacles alone.

While the purpose of these stinging cells is to protect and catch prey, humans often find themselves in the crossfire and end up with a nasty sting.

Although we recommend that you avoid coming in contact with a jellyfish when you cross paths, it’s important to note that many are harmless and do not sting at all. Still, however, it is best to know what to do when jellyfish strike.

Read on to learn about the five types of jellyfish to watch out for in Ireland (and how to treat stings).

5. Common jellyfish – this is the most widespread jellyfish in Ireland

Moon jellyfish are one of the most common types of jellyfish in Ireland.
Credit: / Nathan Rupert

Also known as the moon jellyfish, it can be seen at large year-round and often gathers in dense blooms with creatures of its kind. It is not uncommon to spot this jellyfish species in Ireland in harbours, estuaries, and washed up on beaches.

Their large plate-sized translucent body identifies moon jellies. Four (usually) purple circles can be seen; these are their internal organs. Moon jellyfish do not sting.

4. Barrel jellyfish – the giants of the jellyfish world

Barrel jellyfish are considered one of the giants of the jellyfish world.
Credit: / Cloudtail the Snow Leopard

Barrel jellyfish are considered one of the giants of the jellyfish world. They are one of the jellyfish species in Ireland, specifically off the Rosslare and Wexford Harbours.

They can also be found in the northeast Atlantic and the Adriatic, Mediterranean, Black, and Azov Sea.

Barrel jellyfish are recognised by their mushroom-shaped bell and tentacles, which number eight in total. They can grow to a whopping 90cm across – the size of a dustbin lid – and weigh up to 35 kg.

Although their sting should not be particularly dangerous to humans, it is best to avoid touching barrel jellyfish.

3. Blue jellyfish – the small but stingy one

Blue jellyfish are one of the preetiest but also most threatening jellyfish species in Ireland.
Credit: / Christine

Blue jellyfish are known for their striking blue colour; however, this colouration only appears in maturity.

Boasting a bell-shape, blue jellies grow to about 30 cm across and possess a wicked sting – so best to keep clear of them if you do happen to stumble across.

They are found in the highest numbers off the Irish south and west coasts. Throughout the year, they can be found throughout the entire Celtic Sea.

2. Compass jellyfish – the one with unusual markings

Compass jellyfish have unusual markings that resemble the shape of a compass.
Credit: / richie rocket

Compass jellyfish are unique in their appearance, and it is no wonder how they got their name with such distinct markings.

Found in the northeastern Atlantic Ocean, including the North Sea and the Mediterranean Sea, these jellyfish, with their translucent, yellowish-white tinge, give off a nasty sting. So steer clear of them if you do cross paths.

1. Lion’s Mane jellyfish – one of the most threatening types of jellyfish to watch out for in Ireland

Lion's mane jellyfish are one of the most threatening types of jellyfish to watch out for in Ireland
Credit: / Maritime Aquarium at Norwalk

With its elegantly flowing tentacles that trail behind it in the water, it’s plain to see where this jellyfish got its name.

Translucent with brown to reddish colouring, these are another one of the jellyfish species in Ireland to watch out for. Growing up to 50 cm across, Lion’s Mane jellies prefer the Irish Sea’s cooler waters – especially the waters off of Dublin.

There has been an increase of Lion’s Mane jellies in the waters off the East Coast in recent times. Keep a good distance from these guys, though; their tentacles yield a very bad sting.

How to treat a jellyfish sting

If you think or know that you have been stung by a jellyfish, follow these steps:

  1. Get out of the water or get away from where you came in contact with the jellyfish.
  2. If there is a lifeguard or first aid nearby, seek assistance.
  3. If not, try to remove the stings yourself. First, clean the area with vinegar for 30 seconds – this should flush the stings from your skin.
  4. In instances where tentacles are attached, apply gloves or gently remove using a stick, the edge of a credit card, or tweezers. Do not try to rub the tentacles off.
  5. Painkillers such as paracetamol and ibuprofen should help ease the pain and reduce swelling. A ‘dry cold pack’ may also assist.
  6. If you are experiencing itching to the wound, an anti-histamine cream may be effective.
  7. Keep any puncture wounds clean and dry to avoid them getting infected.

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