|Christmas Tree worm (Spirobranchus giganteus) and Pillar Coral (Dendrogyra cylindrus), with polyps extended|
by B. N. Sullivan
We chose this image for our holiday post because we thought it looked festive. We hope you agree.
The photo, taken during a night dive off Providenciales in the Turks and Caicos Islands, shows a stand of Pillar Coral (Dendrogyra cylindrus) with its polyps extended for feeding. Nestled cozily in the coral is a kind of Polychaete worm called the Christmas Tree worm (Spirobranchus giganteus). The worm burrows into coral and secretes a calcareous tube in which it lives. Only its pair of feathery 'Christmas Tree' shaped crowns are visible outside its tube. The feathery tentacles on the crowns trap tiny tidbits of food, and also are used for respiration.
The Christmas Tree worm can retract its crowns into its tube for protection. When the crowns retract, a structure called the operculum closes snugly over the tube like a lid or a little trap door. Christmas Tree worms come in lots of colors: red, orange, yellow, blue, and white. We also have seen a version that is striped!
We hope all of our readers are enjoying the holiday season, and we wish you all a very happy, healthy, and prosperous New Year.