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Christmas Tree Worm

Named for its festive, tree-like shape, the Christmas tree worm may be small, but it plays an important role in reef ecosystems around the world!

 

Christmas tree worms are typically small — shorter than most people’s thumbs — though most of their body remains hidden inside a burrow they build within coral. Only their colorful crowns are visible — sticking out in a variety of vibrant colors. Each worm has two spiraling crowns of feather-like appendages used for both respiration and feeding on tiny phytoplankton floating in the water.  

When threatened, the worm can retract lightning-fast into its burrow, sealing the entrance with a protective, trapdoor-like structure called an operculum. Once the Christmas tree worm makes its burrow, it will stay there on that piece of coral for the rest of its life. This relationship benefits both the worm and the coral – the worm gets a home, while the worm enhances water circulation around the coral, helping the coral feed! Because they depend on healthy coral to survive, the presence of Christmas tree worms may indicate the health of their coral reef home.

 

 

Depending on coral reefs to survive means that if coral suffers, so do Christmas tree worms. The impacts of climate change on coral — such as ocean warming, acidification, and coral bleaching — pose serious long-term risks to the future of this species.

 

 

Protecting coral reef habitat is key to safeguarding the corals that Christmas tree worms need to survive. Additionally, stopping the expansion of offshore drilling, promoting responsible renewable energy, and other steps to tackle the climate crisis can address the acceleration of warming ocean temperatures that degrade coral habitats. Learn more about how Oceana campaigns to protect our climate here.

 

 

  • Bradbury R. (1986) Does Spirobranchus giganteus protect host Pontes from predation by Acanthaster planci: predator pressure as a mechanism of coevolution? Marine Ecology Progress Series. 
  • NOAA: What are Christmas tree worms? 
  • Petrocelly G. (2022) The Christmas Tree Worm (Spirobranchus giganteus) as a Potential Bioindicator of Coral Reef Health. Berkeley Scientific Journal, 27. https://escholarship.org/uc/item/305555sk 
  • Vinn O. (2011) Microstructure and formation of the calcareous operculum in Pyrgopolon ctenactis and Spirobranchus giganteus (Annelida, Serpulidae). Zoomorphology, 130: 181-188. https://doi.org/10.1007/S00435-011-0133-0 

 

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