UNMASKING THE BLUEBOTTLE REVEALING FOUR DISTINCT SPECIES THROUGH GLOBAL CITIZEN SCIENCE
For over two centuries, the Portuguese man oβ war (Physalia spp) was considered a single, cosmopolitan species, drifting across the worldβs oceans and stinging unsuspecting swimmers. But new genomic research has overturned this long-held view, revealing that Physalia is not one species, but at least four: P. physalis, P. megalista, P. utriculus, and a newly described species, P. minuta. Researchers sequenced the genomes of 151 specimens from around the globe and found strong reproductive isolation between genetic lineages, even when their distributions overlap. This evidence aligns with historical descriptions from the 18th and 19th centuries, which proposed several species that were later dismissed due to limited data.
Crucially, the study integrated over 4,000 photographs from iNaturalist, using citizen science to match distinct morphologies with genetic lineages. These images, contributed by amateur naturalists, swimmers, and lifeguards, allowed researchers to confirm physical differences that earlier taxonomists could not consistently observe due to preservation challenges. The result is a rare success story in which modern genomics, historical records, and participatory science come together to clarify the taxonomy of one of the oceanβs most recognisable creatures.
The discovery not only rewrites the story of Physalia but also challenges assumptions about biodiversity in the open ocean, reminding us that even the most visible marine life can hold hidden complexity, and that everyone, from sailors of the past to todayβs citizen scientists, has a role to play in uncovering it.
Reference: Church et al., 2025. Population genomics of a sailing siphonophore reveals genetic structure in the open ocean.Β Current Biology.
