Christmas tree worms usually reach a length of 1.5 inches and come in a variety of colors.

One purpose of the worm’s appendages is to collect sand to build tubes for anchoring themselves to the coral. Once they have anchored themselves, they won’t move again.

If danger such as a crab or reef fish come near, the Christmas tree worm can seal itself closed for protection.

The spiraled structures on top of the Christmas tree worm, also called crowns or gills, are used for feeding and breathing. They are more similar to feather-like tentacles but do not help the worm move but instead collect oxygen from the current. These tentacles come in many different colors and sizes to match the coral growth surrounding the worm.

They are located throughout the world’s tropical oceans from the Caribbean to the Indo-Pacific. Christmas tree worms prefer shallow tropical coral reefs but have also been found burrowing onto giant clams accidentally.

Christmas tree worms are filter feeders eating plankton and other small particles that drift by. Once the particles get stuck on the plumes of the worm’s tentacles, the cilia will move it towards the worm’s mouth. On the way, large particles are discarded, and sand grains are stored for building tubes later. Christmas tree worms not only have a complete digestive system, but they also have a well-developed nervous system and circulatory system!

Since Christmas tree worms never move from their burrowed coral spot, reproduction is done without contact. To increase their chances of successful fertilization, males and females will release their eggs and spermatozoa into the water at the same time. The embryos turn into larva after 24 hours and drift freely until attaching to coral where it will burrow and begin its life.

Christmas tree worms are a type of tube building bristle worm in the class polychaete.