There are some ocean animals people fear. They include sharks, stingrays, jellyfish, and sea urchins. This is the third in a series of four articles that will separate fact from myth, and give you some concrete advice to help alleviate any remaining fears you may have.
What is a jellyfish?
Jellyfish are invertebrates, which means they don’t have bones. Not only do they not have bones, jellyfish also don’t have brains, teeth, blood, or fins. In fact, they’re 95% water. Despite that, they’re amazingly complex and beautiful animals.
You can find jellyfish in all the world’s oceans and they range in size from approximately .07 inches (2mm) to 10 feet (3m) depending on the species. Jellyfish eat small animals including zooplankton, shrimp, small fish, crabs, and other jellies. At the same time, jellyfish are a favored meal of sea turtles, blue rockfish, molas, dogfish, anchovies, chum salmon, and mackerels. People eat jellyfish too. They’re considered a delicacy in China.
What makes jellyfish dangerous are nemocysts, or venomous stinging cells, located along their trailing tentacles. Nemocysts are like little tiny poison darts buried inside the flesh of the entire length of each tentacle. When something, like a human or a fish, comes in contact with the tentacle, the venom is released.
Another factor to consider is that jellyfish tentacles are practically invisible and can trail far behind its bell (body). Most people don’t even see the tentacles before they’re stung. And, jellyfish live in groups, so if there’s one jellyfish, there are probably more nearby.
What jellyfish are the most dangerous to humans?
- The Australian Box Jellyfish and its relatives, including the tiny (0.2 inches across) Irukandji Jellyfish and the Sea Wasp, are by far the most dangerous jellyfish. In fact, they’re widely regarded as one of the deadliest creatures on earth. Yikes!
- Portuguese Man o’ War are considered the second most dangerous jellyfish to humans. Technically they aren’t actual jellyfish at all, but they drift in the water and have tentacles that sting. They’re found throughout the world’s oceans. While their stings are rarely fatal to humans, in severe cases they can lead to fever, shock, and impaired heart and lung function.
- Lion’s Mane Jellyfish are the third most dangerous kind of jellyfish. They’re the largest jellyfish species with bodies reaching 10 feet across and tentacles trailing over 100 feet. They’ve been known to weigh up to 500 pounds. These jellyfish usually appear in large swarms and are found in colder waters of the North Atlantic and Australia. Their sting is very painful, although rarely fatal.
Jellyfish Myths & Facts
Myth: Jellyfish actively seek to sting humans.
Fact: Jellyfish drift in the water and their venomous tentacles serve as a way to catch their prey and to defend themselves. Since jellyfish don’t have a brain, the idea that they could actively seek to do anything gives them far too much credit.
Myth: Jellyfish washed up on the beach are dead.
Fact: Not always. While jellyfish do need water to breath, they can survive for a time out of water, especially if they are lying in little pools of water or near the tideline.
Myth: Rinse a jellyfish sting with warm fresh water.
Fact: Water helps release the toxins, which makes the pain worse. Rinse a jellyfish sting with vinegar. Vinegar stops the toxins from being released.
Myth: Peeing on a jellyfish sting helps relieve the pain.
Fact: Urine contains a lot of water. If vinegar isn’t available, isopropyl alcohol or sea (salt) water are better than urine.
Things You Can Do to Protect Yourself from Jellyfish
- The obvious advice is the best advice when it comes to jellyfish. Avoid areas populated by jellyfish!
- Observe warning signs. Most beaches post warnings when jellyfish have been sighted nearby.
- Don’t touch or handle jellyfish, even if they appear to be dead.
- Wear protective clothing like waterproof shoes and a wetsuit.
- Wear protective lotion. There’s a jellyfish sting cream available that mimics the secretions of clownfish, a fish that’s immune to jellyfish stings.
- Swim near a lifeguard. They can help in case you do get stung.
— Lisa Dworkin