Head to head
Mediterranean Fanworm vs Christmas Tree Worm
Mediterranean Fanworm
VS Christmas Tree Worm
The Mediterranean fanworm and the Christmas tree worm are two tube-dwelling worms that spread feathery crowns into the water to feed, one in cool harbours and the other on tropical reefs.
| Mediterranean Fanworm | Christmas Tree Worm | |
|---|---|---|
| Scientific name | Sabella spallanzanii | Spirobranchus giganteus |
| Relationship | A tube-dwelling fanworm that feeds with a crown of feathery tentacles | A tube-dwelling worm that feeds with a crown of feathery tentacles |
| Crown | A large, spiral crown of feathery tentacles banded in brown and cream, up to about 15 cm across | Two small Christmas-tree-shaped spiral crowns, about 1.5 to 4 cm tall, in red, orange, blue, white, or yellow |
| Tube | A tough, flexible, leathery tube of mucus and mud, with the worm up to about 40 cm long | A hard tube embedded in living coral, encased as the coral grows |
| Retreat | Pulls its crown into the tube instantly if it is touched or threatened | Withdraws both crowns into its tube in a fraction of a second, sealing it with a plug called an operculum |
| Habitat | Sheltered harbours, piers, and rocky ground of the Mediterranean and the nearby eastern Atlantic | Tropical coral reefs worldwide, from shallow water to around 30 metres |
| Where it travels | Carried on the hulls of ships to Australia, New Zealand, and other countries, where it forms dense clumps | Stays in the same coral head for its entire adult life, living 10 to 40 years |
| Conservation status | Not Evaluated, and an invasive fouling pest in Australia, New Zealand, and elsewhere | Not Evaluated, and common on tropical reefs |
Mediterranean Fanworm vs Christmas Tree Worm: common questions
Which one lives in coral?
The Christmas tree worm, which settles on a live coral colony and burrows into it, so its tube is encased as the coral grows.
Which one is an invader?
The Mediterranean fanworm, which has been carried by ships to Australia, New Zealand, and other countries, where it settles on hulls, wharves, and moorings.
How fast can they retreat?
Both pull their crowns into their tubes almost instantly if touched or threatened, and the Christmas tree worm can do it in a fraction of a second.