Edgartown Parks is warning swimmers about Portuguese man o' wars.
The close relatives of jellyfish have been washing up on the beach on the south shore recently.
You can recognize them in the water by their balloon-like float, but if you see one, get away quickly because its stinging tentacles could potentially be up to 100 feet long.
Their sting is rarely deadly to people but often leads to super painful welts and numbness. Make sure to report a Portuguese man o' war sighting to a lifeguard or ranger.
(Photo by Matt Cardy/Getty Images)
Photo: Getty Images