Spirobranchus giganteus giganteus, or Christmas Tree Worm, is one of the most conspicuous and beautiful tube worms on the reef.
A person would indeed find it hard to believe this flower-like animal is related to the garden worm. However, one only has to think of a garden worm with an outrageous hairdo.
Since it cannot go and get its food, a tube worm’s head has been modified, so the tentacles form a fan. The fan has tiny hairs that drive water through, allowing plankton to be strained and funnelled to the mouth.
These delicate fans – or radioles – have many shadow-detecting eye-spots that sound the alarm when a predator gets too close. In an instant, the worm’s delicate whorl disappears through a trapdoor into its tube. A sharp spike arms the door, ready to impale even the toughest of predatory noses.
The Christmas Tree Worm is one of many species of fan worms that brighten up Cayman’s reefs.
Tom Byrnes is the owner/operator of Cayman Marine Lab. He acquired his Coast Guard Captain’s Licence when he was a teenager and worked as a commercial fisherman in his youth. He got his first diving certificate in 1974 with the YMCA. He has worked in the local dive industry for more than 35 years and has a PhD in Marine Biology.