Worms are not usually known for their beauty, but there is and always should be, an exception to every rule and in this case it is the Spirobranchus giganteus or the Christmas tree worm, a polychaete worm that makes its underwater home in hard corals.
Christmas tree worms are found on coral reefs in tropical waters worldwide. They come in a fantastic variety of colours: orange, white, blue, yellow, brown and pink and can grow up to about an inch long.
These exquisite-looking worms burrow into the face of a coral head and build a chalky tube in which to live. Coral polyps then grow around the worm providing it with a safe, secure home.
This serpulid has a fairly regular segmented body but bears a pair of enormous spiralled gills, a direct translation of its Latin name. These magnificent radioles are not purely decorative but have an important practical purpose too. The feathery gills sift food out of the water and wafts it directly down the food groove. They also collect oxygen from the water and any sand particles gathered are sent to storage sacks to be used later for tube building.
The worms are very susceptible to movement and changes in light and will retract their antennae at the slightest disturbance. After disappearing into their protective tube they will take upwards of one minute to re-emerge. Butterfly fish have been known to try for a nibble on a Christmas tree worm but invariably they are not fast enough; deploying these tactics, the Christmas Tree Worm can live for over 40 years.
For this year’s Festival of Trees, CCMI is using the Christmas tree worm as its event image and inspiration. This is appropriate for more than just the obvious reasons. Both CCMI and the Christmas tree worm play a role in protecting coral reefs. In waters where the voracious crown of thorns starfish, Acanthaster planci, attack hard corals, Christmas tree worms are the last line of defence.
Studies have shown that as a crown of thorns moves onto a coral head that is home to a Christmas tree worm, the worm will retract into its tube only to pop back out seconds later and use its radioles to irritate the underside of the starfish, causing it to beat a very hasty retreat.
This year’s Festival of Trees will help to raise money to support the costs of running the CCMI’s research station in Little Cayman, where the organisation provides education for the young people of the Cayman Islands, thereby continuing to recruit foot soldiers for the cause of reef conservation.
Come and be a part of the Festival at Camana Bay this year and celebrate the Christmas tree worm and its environment, the coral reef. WH
www.reefresearch.org