Christmas Tree Worm
Fast Facts
Latin name: Spirobranchus giganteus
Notable feature: A tube-building worm with brightly coloured “crowns” – feeding structure that look like mini-Christmas trees!
Conservation Status: Not Evaluated
Where in the UK: Tropical coral reefs from the Caribbean to the Indo-Pacific, including Bermuda in the UK Overseas Territories.
Christmas Tree Worm (Spirobranchus giganteus) © Justin Philbois
Coral reefs decked with Christmas Tree Worms are quite a sight. The worms burrow into live coral and build tubes out of calcium around their bodies – providing a protected home.
Their most distinctive feature is their modified mouthparts – a pair of brightly coloured feathery spiral structures in the shape of Christmas trees. The feathery mouthparts are used to breathe and to feed – they filter plankton from the water.
Their “crowns” have light-sensitive molecules scattered across them, helping the Christmas Tree Worms detect the shadow of predators. If a fish comes near, the worm can quickly retract into its burrow.
Each worm has “crowns” of a different colour and pattern and it’s easy to understand why they were given their common name – groups resemble vibrant festive decorations!
- Size: Body length is around 3.8cm.
- Life span: 10 – 40 years.
- Diet: Plankton.
- Reproduction: Christmas Tree Worms reproduce via “broadcast spawning” – where sperm and eggs are released into the water and form free-swimming larvae. When the larva finds a patch of suitable coral it burrows in and begins growing into an adult form, forming its tube – inside which it will stay for the rest of its life.
- When to see: All year round.
- Population Trend: Thought to be stable.
- Threats: Loss of habitat, coral bleaching, raised water temperatures due to climate change, and collection for the aquarium industry affect their numbers locally.
- Interesting Fact: Some of the touch-sensitive plants featured in Avatar were inspired by Christmas Tree Worms!
How you can help:
Buglife is working to increase awareness of invertebrates, but we need your help!
Buglife work to increase awareness of invertebrates and support nature’s recovery through our projects and campaigns, but we need your help!
You can support our work by joining our community or by adopting a Christmas Tree Worm!
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