Most people think that all gelatinous,swimming marine animal encountered at the sea are "jellyfish" and moreover that they all sting. But not all jellyfish are stinging; many are harmless to humans, but it is always best to avoid touching them.
These famous jellies are known for stinging and badly injuring or killing unsuspecting divers and snorkelers. While these nasty cnidarians do cause chaos, Australia is home to multiple amazing species of jellyfish that rarely sting but often amaze divers.
The moon jelly is the most common jellyfish in UK seas, often washing up on our beaches. No need to worry though - it doesn't sting humans.
While box jellyfish are found in warm coastal waters around the world, the lethal varieties are found primarily in the Indo-Pacific region and northern Australia. This includes the Australian box jellyfish (Chironex fleckeri), considered the most venomous marine animal.
Jellyfish sting their prey with their tentacles, releasing a venom that paralyzes their targets. Jellyfish don't go after humans, but someone who swims up against or touches one — or even steps on a dead one — can be stung all the same. While jellyfish stings are painful, most are not emergencies.
Habu-Kurage and box jellyfish are known to have extremely painful stings, Japanese sea nettle are moderately painful, and moon jellyfish are pretty much painless.
Comb jellies are another member of the jellies group and are very similar to jellyfish. Named for comb-shaped paddles on their bodies that they use to swim, comb jellies are soft, round, and transparent. They are also predators, but don't sting, instead capturing prey with sticky secretions.
But – guess what? Those clear, crescent-shaped wobbly jelly shapes aren't jellyfish at all! Instead, they are the egg sac from the conical sand snail, each containing hundreds of snail eggs. So squash away- if you want hundreds of snail eggs between your toes- it's not going to sting you!
The venom of Irukandji box jellyfish (Malo spp.), the smallest jellyfish in the world with an average size of only one centimeter, have been proven fatal to humans (SF Fig.
Aequorea Forskalea
Its cnidocysts (stinging cells) are not dangerous for humans, making it one of the most harmless species of jellyfish.
Aurelia aurita
The venom of Aurelia is harmless for humans and this jellyfish can be touched (in China it is a popular dish) even though, like all jellyfish it is very delicate and contacts can damage it. Aurelia lives in all oceans of the northern hemisphere, where it can be very abundant.
Irukandji jellyfish's stings are so severe they can cause fatal brain hemorrhages and on average send 50-100 people to the hospital annually. Robert Drewe describes the sting as "100 times as potent as that of a cobra and 1,000 times stronger than a tarantula's".
Wear protective clothing such as a full body lycra or neoprene suit, even if in shallow water, as most jellyfish stings occur when wading. This is the number one way of preventing stings, as suits protect up to 75% of the body and cover areas where stings more commonly occur.
The most common type of stinging jellyfish is the bluebottle. These are found in non-tropical areas, especially along the south-eastern coastline of Australia. Their stings are painful, but they don't usually need medical treatment.
The Irukandji has four tentacles, one on each corner, whereas the box has up to 15 tentacles coming from each corner. That's up to 60 tentacles all with millions of injection harpoons filled with venom.
Jelly sacks are not jellyfish. Instead they are an egg mass laid by moon snails. The eggs are encased in the clear, moon-shaped, jelly-like substance. So when you are squishing them between your toes remember you are actually squishing tiny moon snails.
Completely harmless, they exist solely to chow down on microscopic plankton. So, fear not the slimy salp!
Salps are nature's jellybean. This is what a bloom of salps look like. Another strange jelly-like glob you might find on the beach are salps. Salps are semi-transparent barrel-shaped marine animals that form chains with each other.
There have been two confirmed Irukandji deaths in Australia. However, the mysterious deaths of several tourists on the Great Barrier Reef are believed to be linked to the stingers.
What are my chances of getting stung by an Irukandji? Rare. Out of the millions of “people days” each year in the Great Barrier Reef waters, in a particularly bad year, only around 100 Irukandji stings occur in Queensland which require medical treatment.
Irukandji syndrome is a painful, potentially lethal condition caused by the sting and envenomation from multiple jellyfish species. It is characterized by severe pain, muscle cramping, hypertension, and potentially life-threatening cardiac complications.
The Drymonema larsoni, commonly known as pink meanies, were first observed in the Gulf Coast in 2000. Scientists identified it as an entirely new species in 2011. These pretty pink jellyfish are carnivorous and have stinging tentacles that can reach up to 70 feet long.
The most common jellyfish involved is the Carukia barnesi, a species of Irukandji jellyfish. Those stung may experience severe or even excruciating pain.
Most jellyfish stings are harmless. But some jellyfish stings can cause serious harm. If you or someone you're with is stung, get help right away. If you're experiencing life-threatening symptoms such as difficulty breathing, call 911 or go to your nearest emergency room.