Beware the Portuguese man-of-war
The balloon shaped sail of the Portuguese man-of-war is a familiar sight in the southern waters of the Gulf Stream. However in recent weeks a combination of currents and the animals' primitive propulsion system has transported large numbers to beaches along the southeast coast of Rhode Island and Massachusetts where its appearance is something of a rarity.
The beauty of a man-of-war and its long streaming tentacles in the water hides a venomous sting. The animal's tentacles, which can grow to be 40 feet long, are used to secure small fish for food and can inflict nasty welts on any swimmer unlucky enough to encounter one in the water.
Last week, the animals washed up on beaches along the Vineyard's south shore. Chilmark temporarily closed Lucy Vincent and Squibnocket beaches.
A Portuguese man-of-war. Photo by Laurence Madin, Woods Hole Oceanographic Inst.
Laurence Madin, a senior scientist and biologist at the Woods Hole Oceanographic Institution (WHOI), said yesterday that reports of large numbers of men-of-war, prompting beach closures over a wide stretch of coastline from Rhode Island to Boston, was unusual.
He said the cause was likely a combination of wind and currents and an offshoot of the Gulf Stream that has come close to the Cape and Island. "These are animals that do not really swim, they sail essentially. That big inflated float of theirs acts as a sail," he said. "So they are moved by wind and currents, so for them to come up here is probably a combination of things."
The Portuguese man-of-war is not a true jellyfish but belong to the same group, he said. The tentacles contain thousands of stinging cells, each of which is essentially a tiny microscopic coiled up harpoon.
"When that contacts something, especially a combination of a mechanical and chemical stimulus will cause that thing to fire," said Mr. Madin. "It fires into your skin and injects toxin, or poison and in most cases it is just painful. I don't know of any reported deaths due to Portuguese man-of-war."
Mr. Madin said the reported remedy of using meat tenderizer to ease the sting works because it contains a protein that inactivates some of the proteins involved in the stinging cell. Vinegar also apparently works.
He noted that, as with a bee sting some people are likely to have an allergic reaction and that could result in more serious complications. Mr. Madin said the best advice is to steer clear of Portuguese men-of-war in the water and on the beach.