Washed up portuguese men-of-war
 Washed up portuguese men-of-war

 Atknsok, Kathi, The Blue Layer

Man-of-War is a jelly-like marine animal but it's no jellyfish. It belongs to a different group of creatures called the
siphonophores. In fact, these sea creatures are four different polyps that rely on each other to survive. Man-of-Wars are well known for their painful and powerful sting. They can be found in warm water all over the world.
[1] [2]

This stinging animal is called the Man-of-War because it looks a bit like a Portuguese battleship with a sail. It's not built like a battle ship. The body is a gas filled float which can be blue to pink in color (it looks like a bag.) It can be anywhere from three to 12 inches (nine to 30 centimeters.) Underneath the float are clusters of polyps which coiled tentacles hang off of. The stinging tentacles can be up to 165 feet (about 50 meters) long. Sometimes the gas bag will flop over in the water but its muscles pull itself back up. The crest above the float is only a few inches tall and acts like a sail. It relies on the wind to move it from one place to another.

Since it has no control over where it goes Man-of-Wars are often found washed ashore, especially during winter and when the wind is bad. The bag that keeps it afloat must be kept wet. If the bag dries then the Man-of-War dies. To keep it from drying out the animal dips its sail in the water once every so often. When it's in the water, the Man-of-War uses the tentacles to capture small fish, plankton and crayfish. The tentacles paralyze prey. By contracting its muscles, the Man-of-War's tentacles can move fairly quickly.

The stings of the Man-of-War aren't just painful to their prey. It can cause some serious pain and effects to people too. This includes fever, shock as well as heart and lung problems. If you're stung by a Man-of-War pick off any visible tentacles, then rinse with fresh or salt water. Put ice on the area. Because you might go into shock it is important to get medical help as soon as possible.
The toxins from tentacles are about 75 percent as powerful as cobra venom. Even dead Man-of-Wars stranded on the beach can still sting so don't touch them and keep out of the water if they are present.

Recovery periods can vary from several days to several weeks depending on the size of the area effected as well as allergic reaction to the venom.
Man of war can seriously or fatally injure humans
Stinging tentacles contain toxins that can seriously or fatally injure humans.

Atknsok, Kathi, The Blue Layer

See color photo

A beached portuguese man-of-war at Folly Beack, South Carolina
        Folly Beach, SC            Christy Turner
The Portuguese Man-Of-War does have a few enemies: the loggerhead and hawksbill sea turtle. They both will feed on it. A few pilot or scavenging fish that travel with the Portuguese Man-Of-War are immune to the poison. The yellow jack and the man-of-war fish hide within the tentacles and perhaps attract larger prey into the trap and feed on the caught prey.

Ever hear of the  Blue Sea Dragon (Glaucus atlanticus)?  Well this little guy feeds off the man-of-war as well. The stinging cells from the man-of-war are consumed and stored in the sea dragons special sacs called cnidosacs. The sea dragon uses its  own tissues as defense against other predators; that includes humans as well.  If you handle the small sea dragon; you may receive a very painful and potentially dangerous sting.

The discharge of the nerotoxin or venom from the man-of-war can have significant effects as we know on the nervous system.  Laboratory tests have indicated that a thimbleful of venom could kill 1,000 mice within seconds. Tests have proved that frozen venom retains its potency after six yers.

Victims that have made contact with a man-of-war feel as though they have been attacked by a swarm of angry bees or showered with red-hot darts. My own personal experience: feeling of electrical shock on initial contact, then intense burning minutes later.

If a man-of-war had the cobra's muscular power and venom capacity, ocean bathing would be eliminated along some of the finest beaches says Dr. Charles Lane of Miami's Institute of Marine Sciences. Human fatalities have been reported which have been unconfirmed (by this web author). As Dr. Lane elegantly puts it, "persons blundering into the sinister violet-tinted curtain of tentacles will not soon forget it".

The park sign in the photo on the right is interesting to note. While only a few tourist stopped and viewed the information on posted on this sign, it does make clear the following ".
..find a lifeguard or park ranger for first aid. A badly stung person should be treated for shock." My first observance showed miles of beach and no lifeguard or park ranger readily available.

Entering the ocean waters is entering a whole new world. Part of that world is the perils of the Portuguese Men-Of-War.
Assateague Island National Seashore, MD, this park sign warns of the stings of a portuguese man-of-war
The bottom left of this sign at Assateague Island National Seashore, Maryland warns of the
stings from a portuguese man-of-war.


  • Atknsok, Kathie, The Blue Layer, Nelson Austrlia, 1994
  • Microsoft Encarta, 2004
  • www.dnr.state.sc.us, South Carolina Dept Of Natural Resource
  • Lane, Charles, Phd, Man O'War: The Deadly Fisher. National Geographic, March 1963
  • First two photos from The Blue Layer.
  • www.video.nationalgeographic.com/video/manowar_portuguese, National Geographic, April 2017
  • en.wikipedia.org/wiki/Glaucus_atlanticus, Wikipedia, April 2017

 Copyright © 2001-2019 |  PortugueseManofWar.com  Mark Leavitt   | Email 

Back to Main Page