ABSTRACT
Throughout their evolutionary history, serpulids, the calcareous tube-dwelling suspension-feeding polychaetes, formed symbiotic relationships with cnidarians (32 relationships), molluscs (six relationships), brachiopods (three relationships), bryozoans (two relationships), echinoderms (one relationship), foraminifers (one relationship) and worms (one relationship). The absolute majority of symbiotic relationships with serpulids had cnidarian partners (micropredators) in the Mesozoic and Cenozoic. There is no observed escalation in the evolution of symbiotic relationships in serpulids. There may be an optimal frequency of symbiotic relationships for serpulid fauna and when that value was achieved in the Jurassic, it stayed constant during the entire evolution of the group. However, the number of serpulid genera involved in symbiosis increased from the Jurassic (six genera) to the Cretaceous (thirteen genera). It seems that the ability to form symbiotic relationships was in general a useful trait as it spread to various branches of the serpulid phylogenetic tree.
Acknowledgments
Financial support to O.V. was provided by a Sepkoski Grant by the Paleontological Society. J.S. is supported by the NCN grant (nr 2022/45/N/ST10/02230). We are grateful to the Researchers Supporting Project number (RSP2024R140), King Saud University, Riyadh, Saudi Arabia. Mirosław Kacperski and Mariusz Salamon are cordially thanked for providing the crinoid specimen for photographic documentation. We thank Elena Kupriyanova for providing us with the photo of recent Spirobranchus and Carles Ferràndez-Cañadell for providing the photo of serpulid in foraminifer.
Disclosure statement
No potential conflict of interest was reported by the author(s).