Introduction
In the last few days there has been an invasion of Southern Man-o-War or what we like to call ‘Bluebottles’. But contrary to popular opinion, these are not jellyfish, they are siphonophores, of which there are currently about 175 species recognised. It’s an important difference. If you’re looking for how to treat Bluebottle jelly stings in Melbourne, do NOT use vinegar (see below).
Siphonophores and jellyfish come from a different taxonomic class. Which means, they are as different as birds are to gorillas. Instead, siphonophores are colonies of animals that live together. Whereas jellyfish are a single animal.
Where do they come from?
These bluebottles did not originate in Port Phillip Bay because they breed in the open ocean.
The ones appearing on our beaches will have been blown here ahead of the season’s strong southerly and westerly winds. It’s like passing a broom over the sea to create a dense ‘front’ of bluebottles swept ahead. They would have been quite a dense layer when they penetrated Port Phillip Heads.
From here, they would have been caught on currents and winds to reach the northern bay. It’s an unusual set of circumstances that has brought them here but their presence has nothing to do with conditions inside the bay.
How to treat a bluebottle jelly sting
Remove the tentacles with tweezers, then apply saltwater (not freshwater or vinegar) and heat to ease symptoms. They are not generally life-threatening.
What are they?
Thanks to a scientific paper out just a few months ago, we now know there are two species of bluebottle that inhabit our coastal seas: Physalia megalista, P. minuta and P. utriculus. Megalista appears to mean ‘ornately embroidered’ in latin. But the main tell is its long protruding bellow on the air sack. The majority I saw over the summer appear to be either minuta which accords with records on iNaturalist. This recently described species appears to be a southern ocean specialist.
Red siphonophore
For interest, here’s another species. We saw these while on Heron Island during winter a few years ago. The tentacles would occasionally get wrapped around our lips where we had the snorkel. Ouch! The turtles, however, loved to eat them. I think Leatherback Turtles and Ocean sunfish would both happily feast on these creatures too.
Jellyfish in Port Phillip Bay
For more information about jellyfish in Port Phillip Bay, click here.
