Spirobranchus giganteus
Christmas Tree Worm [+]

Kingdom: Animalia
Phylum: Annelida
Class: Polychaeta
Order: Canalipalpata
Family: Serpulidae
Genus: Spirobranchus
species: giganteus
+ITIS +WoRMS

Description & Behavior

The Christmas tree worm, Spirobranchus giganteus, is a Christmas tree-shaped serpulid tube-dwelling worm with magnificent twin spirals of plumes used for feeding and respiration. This cone-shaped worm is one of the most widely recognized sedentary polychaete worms. They come in many colors including orange, yellow, blue, and white and, though they are small with an average 3.8 cm in span, they are easily spotted due to their shape, beauty, and color. The colorful plumes, or tentacles, are used for passive feeding on suspended food particles and plankton in the water. The plumes are also used for respiration. Though the plumes are visible, most of the worm is anchored in its burrow that it bores into live calcareous coral. Christmas tree worms are very sensitive to disturbances and will rapidly retract into the burrow at the slightest touch or passing shadow. They typically re-emerge a minute later, very slowly, to test the water before fully extending their plumes.

World Range & Habitat

The Christmas tree worm, Spirobranchus giganteus, is found on coral reefs in tropical waters worldwide.

» GBIF occurrence data in Google Earth [Tips] | Ocean Biogeographic Information System (OBIS) (World Distribution) [about]

Feeding Behavior (Ecology)

The Christmas tree worm, Spirobranchus giganteus, are polychaete ciliary feeders that feed using their radioles, the hair-like appendages that circle outward from the central spine, to catch phytoplankton floating in the water column. The food is then passed down the food groove by the feeding pinnules (ciliary tracts or tiny hair-like extensions on the surface of cells that generate water currents to move food or mucus). The food particles are sorted and larger particles are discarded. Sand grains are directed to storage sacs to be used later for tube building.

Life History

There are both male and female Christmas tree worms, Spirobranchus giganteus. They reproduce by casting their eggs and sperm into the water. The eggs are fertilized in the water then develop into larvae that settle on coral heads and burrow into the coral.