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CRITTER: Dangerous man o’ wars washing up on our beaches

While surfing at Makaha on O‘ahu’s South Shore one day, I went through a wave and felt like I had been bit by a huge shark. My entire body was in intense pain but when I surfaced I could not see any wounds and I was really confused as to what was happening.

I started shaking and rubbing my arms and noticed little blue jelly like bubbles that covered my chest and arms. The pain was so intense I started to scream and tried wiping off the particles that were stuck to my body and several surfers came to my aid.

They got me to shore and the lifeguards called an ambulance, which took me to a hospital in Honolulu. Little did I know at the time that I had been stung by a highly poisonous man o’ war jellyfish and after being treated for the pain, I was released from the hospital after four hours. I had tiny sores all over my body and lived to share my crazy surf session with friends.

I never saw the man o’ war that stung me because these strange creatures are not actually jellyfish, but an animal called a marine hydrozoan, and they are not a single animal but a community of animals living together. They are made up of tiny animals called zooids that share the same body.

Each zooid has its own function, much like the cells in our body. The top of the man o’ war is a gas filled float that looks like a long blue or pink colored balloon with a ridge on top. This float can be an 1 or 2 inches long all the way up to about 8 inches.

Just below the float are zooids that act as organs and digestive parts then hanging down in the water are long tentacles made of tiny stinging cridocytes that are powerful enough to paralyse fish and even kill humans. These tentacles can be more than 10 feet long and can break away from the man o’ war body and still deliver a powerful sting since they are complete living animals on their own.

The man o’ war can wash up on the beach and die, but the tentacles can stay alive on their own for days and can still sting someone on the beach.

Swimmers and surfers in Hawai‘i usually never see a live man o’ war because they normally live way out at sea, but when we have an unusually strong onshore wind they can be blown into the surf. The waves will often break apart the man o’ war and the long stinging tentacles can float in the surf and stick to your body giving you a powerful sting that hurts for up to five hours. The floating tentacles look like a sting of tiny blue beads and often are clear so they are hard to see.

Our weather and wind patterns are changing here in Hawai‘i and this is causing more of the man o’ wars to wash up into the surf and onto the beach. When they are laying on the sand they are much like an inflated small blue balloon and people often pick them up not realizing they may still be attached to their venomous stingers.

If you get stung by just a few stingers then you will have a pain filled day, but if you get wrapped up by a long chain of stingers like I did you may end up in the hospital. If you ever get stung by a man o’ war or even a normal jellyfish, vinegar breaks down the poison so that it can be applied with hot water and ease the pain until it goes away in a few hours.

In Hawai‘i, we are also having a lot of 2-inch long jellyfish called By-The-Wind Sailors. These jellyfish float on the sea surface and are blown in by the onshore wind just like the man o’ war, but they have a round flat float with a thin tall sail.

They are often blown ashore in huge numbers unlike the man o’ war, which are usually by themselves. The By-The-Wind Sailors do not have stinging cells that can harm people, so even if you run into them in the water they are harmless and if you swim or surf a lot it may be good to do some research so you can tell the two apart.


Terry Lilley is a marine biologist living in Hanalei Kaua‘i and co-founder of Reef Guardians Hawai‘i, a nonprofit on a mission to provide education and resources to protect the coral reef. To donate to Reef Guardians Hawaii go to
Source: The Garden Island

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