A new species of Portuguese man o鈥� war, or bluebottle, has been identified in the waters between Australia and New Zealand, following an analysis of the animals鈥� genetic diversity across the world.
Bluebottles are colonial organisms with long stingers attached to a blue gas-filled float. They are made up of smaller units called zooids, which are genetically identical but have different roles, such as digestion, reproduction and feeding.
In the late 18th and early 19th centuries, naturalists identified three species of Portuguese man o鈥� war, but they were later all placed into one species: Physalia physalis.
Advertisement
Now, a team led by at Yale University has studied the DNA of 133 bluebottle specimens from around the world. The researchers also examined more than 4000 photos of bluebottles posted to the website and carefully examined the morphology of the specimens.
They concluded that there are at least four distinct species with unique physical characteristics and restricted ranges. Three of these correspond to species named over 200 years ago: P. physalis, Physalia utriculus and Physalia megalista.
The fourth, found in the Tasman Sea, has not yet been named. It has multiple tentacles, a smaller, stubbier-shaped float than other species and a less pronounced crest on its float.
The researchers say there are hints that there may also be a fifth species but they do not yet have enough evidence to be certain of this.
Team member 聽at Griffith University in Gold Coast, Australia, says this is the first attempt to comprehensively look at the global genetics and morphology of the animals.
鈥淭hey look like water balloons or plastic bags floating on the ocean and we have just been assuming they are one species,鈥� says Pitt. 鈥淭hey have a diversity that has been hiding in plain sight and it shows how much we don鈥檛 know.鈥�
One mysterious feature of these animals is that a proportion of each population orients its float in different directions.
鈥淏luebottles can be either right or left-handed, meaning most of the bodies and tentacles emerge from the right or left side of the float,鈥� says Church. 鈥淭his changes the direction they drift in response to wind, and can affect which bluebottles blow onto the beach. We don鈥檛 know for certain how this is determined, but our best understanding is that it鈥檚 not genetic.鈥�
Understanding where the different groups of bluebottles are located and the currents that move them around will allow scientists to be able to better predict when a swarm may hit a beach and pose a danger to swimmers, says Pitt.
bioRxiv
