From time to time we see Bluebottles (Indo-Pacific Man o’ War) on our beach, and recently someone reported they'd seen quite a few stingrays in the shallows. Both can sting.
The bluebottle, or Indo-Pacific Man o’ War, is not a jellyfish but a siphonophore, which is a colony of tiny, specialized polyps working together as colonies. The bluebottle is easily recognized by its blue, gas-filled sac (pneumatophore) that floats on the water’s surface. During summer in the Southern Hemisphere, strong winds carry bluebottles to the shores of Australia, where thousands of bluebottle stings are reported each year.
The bluebottle is comprised of four different colonies of polyps that depend on each other to survive. The species is named after one of its polyps, the gas-filled sac, often referred to as “the float,” which resembles a blue bottle floating in the ocean. The float moves depending on the wind and supports the other three types of polyps that are responsible for catching prey, digesting food, and reproduction. The float can be 0.8 to 6 inches (2 to 15 cm) long, while the feeding tentacles reach lengths of 30 feet (10 m).
The ability of these creatures to inflict a nasty sting makes the following info useful to keep around:
How to treat a Bluebottle jellyfish sting | RNZ News:
Surf Lifesaving medical director Dr Gary Payinda said it wanted people to know how to properly treat stings. …
"Irritating them with pressure, or scraping, or caustic things is never a good idea."
Payinda said beachgoers should remove all visible tentacles by hand, then get the sting victim into comfortably hot water.
"That will reduce the pain markedly, within minutes usually," he said.
Payinda said it was also important to watch out for the signs of an allergic reaction after being stung.
"If a person's having not just a rash on the external part of them [...] but also internal symptoms like, their tongue is swelling, or they feel their throat is getting tight, or it's hard to breathe, or they're having vomiting, "Those are all potentially signs of a serious allergic reaction called anaphylaxis." … beachgoers should call an ambulance as soon as symptoms appear. …
Payinda said hot water immersion could also be used to treat stingray stings.