# Spirobranchus

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***Spirobranchus*** is the second largest genus of tube-building [annelid](/source/Annelid) fanworms in the family [Serpulidae](/source/Serpulidae). Members of *Spirobranchus* are known as **Christmas tree worms**.[1]

The worms form a calcareous tube which becomes incorporated into their host coral. The prominent features visible externally are a pair of conical spiral [radiole](/source/Radioles) bundles ("trees"), and an [operculum](/source/Operculum_(animal)) that closes when they retract into their tube.

The *crown* of radioles serves for both food-gathering and respiration. "Christmas tree" refers to the tiered, tapered shape, whilst "*Spirobranchus*" translates to "spiral gill".

## Taxonomy and systematics

The type species *[Spirobranchus giganteus](/source/Spirobranchus_giganteus)* was described by [Peter Simon Pallas](/source/Peter_Simon_Pallas) in 1766 as *[Serpula](/source/Serpula) gigantea*.[2] In 1818, [Henri de Blainville](/source/Henri_de_Blainville) separated "*S. gigantea* de Linné" into a its own genus named in French as "Spirobranche".[3]

## Species

The species in the genus ([World Register of Marine Species](http://www.marinespecies.org/aphia.php?p=taxdetails&id=129582)) include:

- *[Spirobranchus aloni](/source/Spirobranchus_aloni)* Perry, Bronstein, Simon-Blecher, Atkins, Kupriyanova, ten Hove, Levy & Fine, 2018
- *[Spirobranchus corniculatus](/source/Spirobranchus_corniculatus)* (Grube, 1862)
- *[Spirobranchus latiscapus](/source/Spirobranchus_latiscapus)* Marenzeller, 1885
- *[Spirobranchus americanus](/source/Spirobranchus_americanus)* (Day, 1973)
- *[Spirobranchus arabicus](/source/Spirobranchus_arabicus)* Monro, 1937
- *[Spirobranchus baileybrockae](/source/Spirobranchus_baileybrockae)* Pillai. 2009
- *[Spirobranchus cariniferus](/source/Spirobranchus_cariniferus)* (Gray, 1843)
- *[Spirobranchus coronatus](/source/Spirobranchus_coronatus)* Straughan, 1967
- *[Spirobranchus corrugatus](/source/Spirobranchus_corrugatus)* Straughan, 1967
- *[Spirobranchus decoratus](/source/Spirobranchus_decoratus)* Imajima, 1982
- *[Spirobranchus dendropoma](/source/Spirobranchus_dendropoma)* Mörch, 1863
- *[Spirobranchus eitzeni](/source/Spirobranchus_eitzeni)* Augener, 1918
- *[Spirobranchus gardineri](/source/Spirobranchus_gardineri)* Pixell, 1913
- *[Spirobranchus giganteus](/source/Spirobranchus_giganteus)* (Pallas, 1766)
- *[Spirobranchus incrassatus](/source/Spirobranchus_incrassatus)* Krøyer in Mörch, 1863
- *[Spirobranchus kraussii](/source/Spirobranchus_kraussii)* (Baird, 1865)
- *[Spirobranchus lamarcki](/source/Spirobranchus_lamarcki)* (Quatrefages, 1866)
- *[Spirobranchus latiscapus](/source/Spirobranchus_latiscapus)* (Marenzeller, 1885)
- *[Spirobranchus lima](/source/Spirobranchus_lima)* (Grube, 1862)
- *[Spirobranchus maldivensis](/source/Spirobranchus_maldivensis)* Pixell, 1913
- *[Spirobranchus minutus](/source/Spirobranchus_minutus)* (Rioja, 1941)
- *[Spirobranchus murrayi](/source/Spirobranchus_murrayi)* Pillai, 2009
- *[Spirobranchus nigranucha](/source/Spirobranchus_nigranucha)* (Fischli, 1903)
- *[Spirobranchus paumotanus](/source/Spirobranchus_paumotanus)* (Chamberlin, 1919)
- *[Spirobranchus polycerus](/source/Spirobranchus_polycerus)* (Schmarda, 1861)
- *[Spirobranchus polytrema](/source/Spirobranchus_polytrema)* (Philippi, 1844)
- *[Spirobranchus pseudopolytremus](/source/Spirobranchus_pseudopolytremus)* Pillai, 2009
- *[Spirobranchus richardsmithi](/source/Spirobranchus_richardsmithi)* Pillai, 2009
- *[Spirobranchus spinosus](/source/Spirobranchus_spinosus)* Moore, 1923
- *[Spirobranchus taeniatus](/source/Spirobranchus_taeniatus)* (Lamarck, 1818)
- *[Spirobranchus tenhovei](/source/Spirobranchus_tenhovei)* Pillai, 2009
- *[Spirobranchus tetraceros](/source/Spirobranchus_tetraceros)* (Schmarda, 1861)
- *[Spirobranchus triqueter](/source/Spirobranchus_triqueter)* (Linnaeus, 1758)
- *[Spirobranchus zelandicus](/source/Spirobranchus_zelandicus)* Pillai, 2009
- *[Spirobranchus zibrowii](/source/Spirobranchus_zibrowii)* Pillai, 2009

## References

1. Iñiguez, Abril; Starger, Craig; Kupriyanova, Elena; Willette, Demian; Varman, Tristan; Drew, Joshua; Toha, Abdul; Maralit, Benedict; Carpenter, Kent; Barber, Paul (2013-01-01). ["Phylogeography of the Christmas Tree worm Spirobranchus corniculatus (Annelida, Serpulidae) from the Coral Triangle, Australia, and Fiji"](https://digitalcommons.odu.edu/biology_fac_pubs/645). *2013 International Polychaete Conference: IPC2013: Program and Abstract Handbook: IPC International Polychaete Conference, Sydney 2013: 4-9 August 2013, Australian Museum, Sydney, New South Wales* Christmas Tree [Worms] is a common name given to a group of large and colourful serpulid polychaetes of the genus Spirobranchus that are obligate symbionts of hermatypic corals commonly found in tropical and subtropical regions world-wide.

1. ["WoRMS - World Register of Marine Species - Spirobranchus Blainville, 1818"](https://www.marinespecies.org/aphia.php?p=taxdetails&id=129582). *www.marinespecies.org*. Retrieved 2026-04-11.

1. Blainville, Henri Marie Ducrotay de. (1818). Mémoire sur la classe des Sétipodes, partie des Vers à sang rouge de M. Cuvier, et des Annélides de M. de Lamarck. *Bulletin des Sciences, par la Société Philomatique de Paris.* 1818: 78-85., *available online at* https://biodiversitylibrary.org/page/4146409 (p. 79).

## Bibliography

- Ruppert, Edward E.; Richard S. Fox; Robert D. Barnes (2004). [*Invertebrate Zoology: A Functional Evolutionary Approach*](https://archive.org/details/isbn_9780030259821/page/963). 7th ed. Belmont, CA: Brooks/Cole - Thomson Learning Inc. pp. [963](https://archive.org/details/isbn_9780030259821/page/963). ISBN 0-03-025982-7.

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Adapted from the Wikipedia article [Spirobranchus](https://en.wikipedia.org/wiki/Spirobranchus) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Spirobranchus?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.