#bluebottle

(Moon jellyfish)

This is ALSO a jellyfish!

(Giant phantom jellyfish)

These are not jellyfish.

(Comb jellies, unsure of species; they are not even in the same phylum (large group of related organisms) as jellyfish (cnideria) but are their own phylum, ctenophora)

And this is most certainly NOT a jellyfish!

(or even a singular animal, for that matter)

'Small bladder'

Until recently the Bluebottles were considered a single species, the Portuguese Man-o-War Physalia physalis, but genetic and morphological evidence has split that up into four or five. This one is found in southern oceans.

Physalia are colonial organisms, with a variety of specialised zooids developing from a single egg. One becomes the gas-filled float, which doubles as a sail, and is set at a slight angle to the rest of the animal underwater, and that angle may be to the left or right. This ensures that prevailing winds and currents don't strand the entire armada on the beach, since half the fleet is sailing away from shore.

Other zooids in the colony special in catching and digesting prey, using long tentacles covered in powerful stinging cells. Others specialise in reproduction. In other siphonophore species, there may be other kinds of zooids.

Bluebottle stings can be serious - there have been a few fatalities in the Northern Hemisphere. First Aid requires getting help, not rubbing the stung area, washing off the stung area with seawater to remove any remaining tentacles and nematocysts, and immersing the area in water as hot as you can comfortably tolerate for 10 minutes - 40C will denature the venom in the sting. If the symptoms persist or for stings that cover a particularly large area, or across the throat & face call 000 (in Australia).