The Brihanmumbai Municipal Corporation on Tuesday put up banners and advisories warning people against walking barefoot along the city’s beaches after scores of venomous blue bottle were spotted along the coastline, reported the Hindustan Times. A day earlier, the Maharashtra fisheries department had also issued an advisory.

The blue bottle, a venomous marine organism, also known as Portuguese Man O’ War, are spotted on Mumbai’s sandy shores during the monsoon. They are pelagic creatures, which mean they neither live close to the bottom of a water body or near the shore, and measure up to six inches. Their sting can cause itching and pain for hours.

“In the advisory issued to citizens as well as the municipal corporation, we have spoken against walking barefoot on the beach – especially close to the shoreline,” said Rajendra Jadhav, joint commissioner of the department. “However, as a blue bottle sting is not fatal, people need not panic.”

Since August 3, life guards and marine experts have reported more than 100 blue bottle stings from the beaches of Girgaun Chowpatty, Aksa, Juhu, and Versova.

An expert from the Marine Life of Mumbai, an initiative run by citizens, said the blue bottle could sting on contact even if they appeared to be dead and prone. “The pain is unbearable because the blue bottle’s sting is venomous,” marine expert Pradip Patade said.

Patade said that applying vinegar to the injury was not advisable. Last month, the Central Marine Fisheries Research Institute had issued an advisory, asking people stung by jellyfish to wash the affected area with sea water and seek medical help instead of applying vinegar, he said. They are also advised not to touch the affected area.