Poisonous Box Jellyfish Stings In Singapore – What You Need To Know
Time to stay out of the open waters at Sentosa, Lazarus Island and St John’s Island for awhile
Sightings of the deadly box jellyfish in Singapore have been reported earlier this month, and there are reports of at least two people getting stung by this venomous sea creature here. Suffice to say, you and your family should not be swimming in the open waters at Sentosa, Lazarus Island and St John’s Island anytime soon. To help you stay informed and keep your family safe, here’s what you need to know about the box jellyfish and other species of jellyfish that have been spotted in Singapore, and what to do if someone has been stung.
What are jellyfish?
Some drift along the currents aimlessly, while others glide through the sea to sting their prey. Some glow in the dark, while others unleash deadly venom.
These sea jellies, which are made up of 95 per cent water, have evolved and roamed the seas for at least half a billion years. These ancient creatures are boneless, bloodless and brainless, but they outlived dinosaurs. They have simple sensory organs on their bells and tentacles to detect light, changes in the water and the touch of other animals.
Jellyfish are found all around the world, from deep oceans to shallow coastal areas.
If a jellyfish washes up on the beach, it would most likely evaporate and dry up due to its high water content. But do not touch the dying blob as its stingers can still shoot venom.
Do all jellyfish sting?
All jellyfish have stings, but not all of them are strong enough to harm the skin. Some stings barely feel like a tingle, while some are not felt at all. For instance, the renowned Jellyfish Lake in Palau is popular with tourists, who swim alongside a swarm of harmless golden sea jellies.
On the other end of the spectrum is the box jellyfish — one of the most deadly animals on the planet. They can grow up to 3m long and, once a person is stung, the venom can immediately attack the heart, nervous system and skin cells. It may cause the victim to go into shock within minutes.
The bells and tentacles of most jellyfish are dotted with tiny cells filled with a dart-like stinger, which releases venom when triggered. This means that the gelatinous bell may not be as innocuous as it looks.
Some jellyfish can also sting in two other unusual ways - without touching the victim, and through larvae.
Some upside-down jellyfish with no tentacles will release a gooey mucus filled with microscopic particles containing stinging cells. When divers swim near those jellies, they feel a stinging sensation similar to an irritating itch or burn.
The larvae of the thimble jellyfish, which are usually found off the coasts of Florida and the Caribbean, are barely visible, appearing like a speck of finely ground pepper, but they pack a painful punch.
Once stung, the skin can develop a bumpy rash, sometimes with blisters. This condition is called "seabather's eruption". Other symptoms, which include headache, vomiting and urethritis, may occur. As the larvae are small enough to creep into swimwear and swim caps, covered skin will not be spared.
In 1987, more than 300 thimble jellyfish specimens were collected from the waters off the west coast of Singapore.
Sting incidents at the beaches of Sentosa were reported from 2010 to 2017. There was a spike in cases in 2010, when 101 sting incidents were reported, compared with the average of 30 cases annually in other years. During those years, more incidents were reported at Palawan Beach, compared with Siloso and Tanjong beaches. In 2010, there was a bloom of unidentified Semaestomae jellyfish in the waters around Sentosa.
If you are stung by a jellyfish, seek medical attention immediately. Meanwhile, rinse the affected area with seawater or vinegar and do not try to remove the tentacles yourself.
Types of Jellyfish in Singapore:
This species is recognised by its long, ribbon-like oral arms that can extend up to 50cm, and large brown spots at the edge of the bell. Also known as the Indonesian sea nettle, the jellyfish carries powerful stings that can cause an intense burning sensation on skin. Swelling will occur, and it may take several weeks to heal.
Do not touch the jellyfish if it is stranded on the beach, as the stingers remain active even after the creature is dead.
However, small fish have been seen swimming alongside the jellyfish's arms and tentacles, unharmed. These fish could be seeking protection from predators, or feeding on morsels of undigested food that the sea jellies leave behind.
Sightings: Raffles Marina, St John's Island, Pulau Hantu and Terumbu Semakau.
This jellyfish is so named because it prefers to rest its bell against the sea bed, with its stout oral arms outstretched. It is sometimes mistaken for a sea anemone.
Local researchers suspect that the jellyfish can release mucus filled with venom into the water, but there is currently no data to prove this.
The jellyfish contains single-celled algae that undergoes photosynthesis to produce food. The food is shared with the jellyfish, which provides shelter and minerals for the algae in return.
Since it relies on photosynthesis, the animal is found in shallow waters, on seagrass meadows, reef flats or mangroves - usually in the Southern Islands.
Sightings: Pulau Semakau and Kusu Island, among other Southern Islands.