Christmas Tree Worms are truly captivating inhabitants of the coral reef, and seldom will you find a scuba diver that will simply pass on by a coral-head teeming with these tiny creatures without being drawn to their beauty, or take a macro photograph, or to simply give them a gentle flick just to see them retract into the coral head like a mesmerizing vanishing trick.
Christmas Tree Worms or Spirobranchus giganteus, are tiny cone shaped tube-dwelling worms that have spectacular twin spiral plumes containing feather-like tentacles that serve as the worms ‘mouth’ for filter feeding, as well as act as its breathing apparatus or ‘gills’. These creatures do not move, but instead anchor themselves into live coral. The worm builds a tube on the surface of the coral, and as the coral grows, the tube gets buried inside the skeleton of the coral itself. Only the two Christmas tree like feathery crowns are exposed of the worm, which it uses to catch plankton with.
The Christmas Tree Worm if threatened can withdraw its feathery head within the blink of an eye. They are very sensitive to disturbances, and even the slightest touch, disturbance in the water or even a passing shadow can cause the worm to retract its head, which it will re-emerge in a minute or so gradually testing its surroundings before reaching its fully extended state.
Instantly recognizable by its bright colors, Christmas tree worms range from orange, yellow, blue, and white, and additionally several different color combinations and patterns. This species is widely distributed throughout the world’s tropical oceans, known to occur from the Caribbean to the Indo-Pacific.
While the importance of the Christmas Tree Worm to the coral reef or its direct benefit or harm it causes to the coral itself is unknown, the worm is an extremely popular underwater photographic subjects for scuba divers as its varied colors and complex spiral structure is magnificent to behold.
photos from flickr by: divemasterking2000, Boogies with Fish, will48324, Nick Hobgood
