Published: 22 July 2020

Experts Debunk Myths About Sea Jellies

Recently, box jellyfish has been reportedly sighted in Singapore’s waters and affecting swimmers and beachgoers. So what do you do when you spot a jellyfish? And what do you do when you get stung? Hear it from S.E.A. Aquarium’s very own ‘babysitter’ of sea jellies – aquarist Vivian Cavan.

How do you identify a ‘poisonous’ sea jelly?

Vivian: First and foremost, let’s correct the terminology: all sea jellies are venomous and not poisonous. Venomous animals are those that bite (or sting) to inject their toxins, whereas poisonous animals are those that unload toxins when you eat them. There’s a famous saying to remember it: 'If you bite it and you die it's poison, but if it bites you and you die, that's venom.’

In the case of sea jellies, look out for their tentacles – which contains thousands of small stingers called nematocysts – as those are the parts that sting. Most sea jellies stings can inflict mild to medium pain, depending on your threshold. A handful of species, such as box jellies, are potentially deadly to humans. In fact, the box jelly is regarded as one of the most venomous marine animals in the world.

What should you do when you’ve been stung by sea jelly? Pee on that area?

Vivian: LOL. Please, don’t do that. It’s a myth and it actually makes it worse. You should apply vinegar to stop the nematocysts from discharging more venom. If vinegar is not readily available, soak the area in warm (not boiling) water to help lessen the pain. Then quickly get medical attention. 


What are some common misconceptions about sea jelly?

Vivian: That they’re called ‘jellyfish’ when they’re not fish at all. Fish are vertebrates and breathe through their gills. Sea jellies, on the other hand, are invertebrates, meaning they have no backbone and they absorb oxygen from water through membranes. 

Also, we often hear guests (parents, some of you are guilty of these too) saying that our sea jellies are amazing because they can change colours. It’s actually our light effects! As Sea jellies are almost transparent, we use these glow lightings to enhance the habitat, so that guests can have a closer look at their fascinating bodies and movement in water. 

What are some fascinating facts about sea jelly?

Sea jellies are simple animals, with a very interesting life cycle with two life stages. They do not have brains, hearts, or eyes, and are comprised of 95 percent water. These creatures have been around since before the time of dinosaurs!

What are the types of sea jellies at S.E.A. Aquarium?

S.E.A. Aquarium currently showcases three species of sea jellies: blue blubber jellies, moon jellies and the Atlantic sea nettles.

Vivian at work 1000x500

How do you care for sea jellies at S.E.A. Aquarium?

On a daily basis, we feed every single sea jelly specimen individually using a pipette, so you can imagine the amount of tender and loving care that go into caring for our jellies. 

Over the years, we have been breeding a variety of species including the moon jellies and black nettles. Successful breeding in the aquarium ensure sustainable captive populations and less reliance on suppliers. Furthermore, through the captive breeding of existing population, it can facilitate the exchange of selected species (along with the husbandry knowledge) with other aquariums to maintain a genetically diverse and healthy population.