Don’t get stung on Whanganui beaches this summer.

Bluebottles dotted the coastline yesterday. Several dozen of the small blue jellyfish (also known as Portuguese man-of-war jellyfish) were evident at Castlecliff Beach, and further along towards the North Mole.

Beach visitor German student Sarah Metzger had not seen one before yesterday and did not know they could sting. “We don’t get them in Germany,” she said.

As with any sting, the sensation is unpleasant, and its severity depends on the amount of contact the skin has had with the tentacle. Although extremely unlikely, it is possible that a bluebottle sting may cause a severe allergic reaction that can be life-threatening, according to the Ministry of Health.

If a person who has been stung by a bluebottle develops chest tightness or difficulty breathing and is getting worse, it is time to get urgent medical help, they advise.

Mostly it just hurts. First aid consists of carefully removing any tentacles left on the skin, and bathing with warm water for 20 minutes. Use of vinegar is not recommended as bluebottles differ from other jellyfish, where vinegar can be applied.

Dog owners should also be careful.