Spirobranchus corniculatus, commonly referred to as the Indo-Pacific Christmas tree worm, is a species of tube-building annelid fanworms in the family Serpulidae.[1] Belonging to the class Polychaeta, it is recognized for its bristle-like tentacles and the presence of a structure called radioles. It is widely encountered and recognized for its unique resemblance to a conifer and its diverse array of colors.[2] Initially presumed to be part of a species group including Spirobranchus cruciger and Spirobranchus gaymardi, it has been determined to be a singular, morphologically adaptable species inhabiting the Central Indo-Pacific region.[3]
The Christmas tree worm is very vibrant in color and changes its color based on depth, camouflage, and a scare tactic.[4] It has bright spiral rings around its body segments or radioles, which can number more than 200 segments.[5] The body is abnormally large, ranging up to long and wide.[5]
The species predominantly engages in reproduction throughout its lifespan. Males use their coloration to attract females.[4] During mating, females emit a pheromone that signals males to release sperm. In turn, females release eggs; this action is called spawning. Larvae are characterized by an elongated body.[6] The species also uses its color to make predators second guess their meal. The species primarily consumes suspended food particles, phytoplankton, and microalgae.[4]
Spirobranchus corniculatus can be found in the tropical Indo-Pacific, specifically in corals such as Porites lobata, which are typically found in Hawaiian waters.[5] The Christmas tree worm inhabits depths of [6] and can also be found living on almost every species of coral.[4] It is mostly encountered in the eastern side of the globe, spanning Southeast Asia, the Indian Ocean, the central Pacific, and the northern region of Australia.