Common name: Christmas Tree Worm

General information

The Christmas Tree Worm (Spirobranchus giganteus) is a colorful marine polychaete worm renowned for its distinctive, tree-like appearance. These worms are named for their spiral, plume-like gills that resemble the branches of a Christmas tree. Each worm has two of these brightly colored crowns that can be a variety of hues including red, orange, yellow, blue, and white.

These worms are sedentary, embedding themselves in live hard corals, such as stony corals from the genus @species:porites. Once settled, they do not move from their chosen spot. They are filter feeders, capturing plankton and other small particles from the water column with their feather-like radioles.

Care

In the aquarium, Christmas Tree Worms require stable water conditions and should be housed in tanks with established live rock and a mature coral community. They need moderate to strong water flow to assist in feeding and respiration, but care should be taken to avoid direct, high-velocity currents that could damage their delicate structures.

Feeding can be supplemented with liquid plankton or other fine particulate foods designed for filter feeders. It's important to ensure that the tank is free from predators that might harm these worms, such as certain species of wrasses and large angelfish.

Reproduction

Christmas Tree Worms are gonochoristic, meaning individuals are distinctly male or female. They reproduce by spawning, where eggs and sperm are released into the water column. Fertilization occurs externally, and the larvae are planktonic before settling onto a suitable substrate to grow into adults.

Symbiosis

Spirobranchus giganteus has a commensal relationship with the corals they inhabit. The worm benefits from the coral's structure for protection and substrate, while the coral is not harmed by the worm's presence. In fact, the worm's feeding activity can help keep the coral clean by reducing sediment accumulation.

Habitat

Christmas Tree Worms are found in tropical coral reefs around the world. They prefer to embed in the hard skeletons of stony corals, particularly those of the genus Porites. These worms are typically found at depths where light is sufficient for coral growth, often between the intertidal zone and about 30 meters deep.