Creature Feature: Christmas Tree Worms
December 17, 2022
The Christmas Tree Worm is a colorful marine worm with beautiful, spiraling plumes that resemble – you guessed it – a Christmas tree! These animals can be a variety of colors from red, orange, yellow, blue and white. The “Christmas tree” shape shown in the image is the animal’s radioles, which can be up to about 1.5 inches in diameter. Each worm has two of these plumes, which are used for feeding and respiration. The rest of the worm’s body is in a tube in the coral, which is formed after the larval worm settles on the coral and then the coral grows around the worm. The worm’s legs (parapodia) and bristles (chatae) protected within the tube are about twice as large as the portion of the worm visible “tree” above the coral. If it worm feels threatened, it can withdraw into its tube to protect itself.
The Christmas tree worm lives on tropical coral reefs throughout the world, in relatively shallow waters less than 100 feet deep. The tubes that Christmas tree worms live in can be up to about 8 inches long and are constructed of calcium carbonate. The worm produces the tube by excreting calcium carbonate that it obtains from ingesting sand grains and other particles that contain calcium. The tube may be much longer than the worm, which is thought to be an adaptation that allows the worm to withdraw fully into its tube when it needs protection. When the worm withdraws into the tube, it can seal it tight using a trapdoor-like structure called an operculum. This operculum is equipped with spines to fend off predators.
The Christmas tree worm feeds by trapping plankton and other small particles on their plumes. Cilia then pass the food to the worm’s mouth.
There are male and female Christmas tree worms. They reproduce by sending eggs and sperm into the water. These gametes are created within the worm’s abdominal segments. Fertilized eggs develop into larvae that live as plankton for nine to 12 days and then settle on coral, where they produce a mucus tube that develops into a calcareous tube. These worms are thought to be capable of living over 40 years.
Happy Holidays and enjoy spotting the Christmas Tree Worms – what an amazing world we call home!