Portuguese man-of-wars found in Chatham and Yarmouth: What you should know

Sarah Carlon, Cape Cod Times
·2 min read
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EDITOR'S NOTE: This story was updated Aug. 15, 2022, to remove a photo.

Several Portuguese man-of-wars, a close relative of the jellyfish, were found in Chatham and Yarmouth Monday and Tuesday, temporarily closing beaches in those towns to swimmers.

Yarmouth's Department of Natural Resources shared on Facebook Monday that all  beaches on Nantucket Sound would be closed due to man-of-war sightings. The next day, the town of Chatham shared on Twitter that Harding's Beach would be closed until 1:30 p.m. that day due to man-of-wars washing ashore as well.

Man-of-wars cause painful sting

According to NOAA's National Ocean Services website, Portuguese man-of-wars look like jellyfish, but they are actually siphonophores, and can be recognized by their prominent blue, violet or pink upper half.

The Portuguese man o’ war is recognized by its balloon-like float, which may be blue, violet, or pink and rises up to six inches above the water line.
The Portuguese man o’ war is recognized by its balloon-like float, which may be blue, violet, or pink and rises up to six inches above the water line.

Typically found in tropical or subtropical climates, a man-of-war's tentacles grow to be 30 feet long and can extend up to 100 feet.

Although rarely deadly to humans, the sting from a man-of-war is very painful and can cause welts on the skin. Man-of-wars can still deliver a strong sting even after being washed ashore for weeks, which makes them dangerous to beachgoers.

More: Meet the new Cape Cod wash-ashore: Portuguese man-of-war

"Everything weather-wise was consistent with man-of-wars," said Bill Bonnetti, director of Yarmouth's Natural Resources Division. "There was a significant southwest wind, the tide came in in the morning and with the heat we've been having lately, it brought them in."

Bonnetti said the increased temperatures the Cape has been experiencing over the past few weeks probably contributed to the man-of-wars found on the beaches — several were found in Yarmouth alone.

Patrolling beaches for man-of-wars

"I don't remember weather patterns like this last summer, but it's an anomaly to have this amount wash up," he said.

South side beaches reopened Tuesday in Yarmouth and the natural resources department patrolled the beaches early in the morning keeping an eye out for any man-o-wars.

As of Wednesday, no more man-of-wars have been found in Yarmouth or Chatham, according to the town's natural resources departments.

Sarah Carlon can be reached at: scarlon@capecodonline.com or on Twitter: @sarcarlon

This article originally appeared on Cape Cod Times: Portuguese man-of-wars cause beach closings in Chatham and Yarmouth