Decades-old museum specimens reveal 10 extraordinary new worms
Scientists have discovered that one of the most unusual creatures in the animal kingdom is far more diverse and evolutionarily complex than previously known. An international team led by the University of Göttingen has reconstructed the evolutionary history of branching marine worms—rare annelids that live hidden inside sea sponges and whose bodies branch repeatedly into multiple posterior ends.
Scientists have uncovered that branching marine worms, previously thought to be a single species, are actually a highly diverse group of 13 distinct forms. An international team led by the University of Göttingen reconstructed the evolutionary history of these worms, living hidden inside sea sponges, using a combination of DNA sequencing from museum specimens and newly collected samples.
The findings, published in the Zoological Journal of the Linnean Society, reveal that the worms form two major lineages: one belonging to the genus Ramisyllis and the other to a newly discovered genus, Cladosyllis. Branching worm diversity was hidden for over a century, with some species inhabiting deep-sea glass sponges and others living in shallow-water sponges.
The study suggests that specialization on different sponge hosts drove their diversification and evolution. Researchers believe many more branching worm species remain undiscovered, making these animals a potential model for studying complex body forms, symbiosis, and biodiversity in marine ecosystems.
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