Christmas Tree Worm
Spirobranchus giganteus
Crown to 4cm

2 spiralling crowns of radioles. Double-horned operculum extends from between radioles. Calcareous tube with large spiral protusion. Highly variable colours and markings.

Found on living coral reefs, protected by their calcareous tubes., usually below 10ft (3m). Their food consists of zooplankton, phytoplankton, and detritus particles. They extend feeding palps from the opening of the tube and prey is trapped and moved by tiny cilia lining the feeding apparatus towards the opening of the tube and into the mouth
These worms have a mutualistic symbiotic relationship with the coral, with the coral providing support and protection while it enhances water circulation for the coral's feeding.
They are highly sensitive to movement and quickly retract their crowns and close the operculum. The radioles will then re-emerge slowly, with 2 pinkish horms appearing first.

Life Cycle
Christmas tree worms do not mate but engage in external fertilization. There are both male and female worms which produce their gametes within their abdominal segments. Male and female worms release their sperm and eggs into the water column. Fertilized
eggs develop into larvae that live as plankton for 9-12 days and then settle on coral, where they produce a mucus tube which develops into a calcareous tube.
The life span of Spirobranchus giganteus is over 30 years.
    Ecological Descriptors
Habitat Size (cm) Diet Behaviour Sex 
Co 4
Pla I F
Christmas Tree Worm