9 Fascinating Facts about Christmas Tree Worms

1. They can live to over 40 years old

Christmas Tree worms are long-lived, although pollution and climate change might reduce their lifespan.

2. Two Christmas Trees are actually One Worm

Each worm has two crowns or Christmas Trees. The worms come in a myriad of colours, but a worm’s two crowns are always the same colour.

3. They breath using their Christmas Trees

As well as breathing, the feathery trees also waft food down to the mouth.

4. At sign of danger they whisk down into the coral

On sensing danger, the worm quickly retracts its crown into its tube in the coral and closes the entrance with a trapdoor called an operculum. It will stay down there for about a minute, before re-emerging very slowly to check that the danger has gone.

5. Some are male and some are female

There are both male and female Christmas tree worms.

6. They are very choosy where they live

Different species of Christmas Tree Worms are very selective where they live. The larger ones often choosing a specific species of coral. Smaller species will also choose artificial substrates as their home.

7. They protect the coral

The worms are important for the health of coral reefs and help protect corals from invasive sea stars whilst also preventing the coral being overgrown with algae.

8. They live all around the world in tropical seas

They’re easy to find and very photogenic, making them great subjects for macro photography. As long as you have the patience to wait and not disturb them into shooting back into their tubes. You might see them down to depths of 30 m.

9. There are several species

Although often identified as Spirobranchus giganteus, there are several different species. S. giganteus lives in the Caribbean. In the Indo-Pacific  S. corniculatus and other species take over.

References and Further Reading

Eijiroh Nishi, Moritaka Nishihira. Age-estimation of the Christmas Tree Worm Spirobranchus giganteus (Pomlychaeta, Serpulidae) Living Buried in the Coral Skeleton from the Coral-growth Band of the Host Coral. https://doi.org/10.2331/fishsci.62.400

Perry et al. Substrate selection of Christmas tree worms (Spirobranchus spp.) in the Gulf of Eilat, Red Sea