Organisms associated with siphonophores revealed by short-read whole-genome sequencing

Siphonophores, creatures found in the open ocean, are known to have a variety of organisms associated with them, such as prey, parasites, microbes, and other organisms. However, the specific details of these associations have remained largely unknown until now. Scientists have now conducted a study on molecular bycatch, which refers to the DNA captured during siphonophore genome sequencing.

By reanalyzing 213 specimens of Physalia, Nanomia, Bargmannia, and other siphonophores sequenced in four previously published studies, the researchers were able to recover 104 bacterial genomes, forming 32 genome clusters. These clusters included recurrent Metamycoplasmataceae and diverse proteobacteria, groups that have also been found in association with other cnidarians.

The bacterial communities varied among Physalia species sampled in the southwestern Pacific. Additionally, non-siphonophore eukaryotes were identified from ribosomal markers in 38 specimens, including fish and copepods, which are likely prey. Parasitic flatworms and Perkinsela-like relatives of amoeba endosymbionts were also found.

One notable finding was the presence of Alfonsino (Beryx) sequences in a Hawaiian P. utriculus specimen, suggesting the capture of pelagic young of deepwater fishes. This molecular bycatch study reveals the diverse range of organisms associated with siphonophores, discovered from specimens already collected for genome research.