Christmas Tree Worm (Spirobranchus giganteus) Care Guide
Spirobranchus giganteus is a small serpulid worm with two spiral radiole crowns that embeds its tube in living coral and filter feeds.
Compiled by Aquairi from published sources · Published · Updated
Overview
Spirobranchus giganteus is a marine polychaete of the family Serpulidae. According to Wikipedia it has two crowns shaped like Christmas trees, composed of feather-like tentacles called radioles, which are highly derived structures for both feeding and respiration. The worm is typically sold embedded in a chunk of its living host coral.
Taxonomy
- Phylum: Annelida
- Order: Sabellida
- Family: Serpulidae
- Scientific name: Spirobranchus giganteus
Habitat
Per Wikipedia the species ranges from the Caribbean to the Indo-Pacific and is commonly found embedded entirely in heads of massive corals, such as stony Porites and brain corals. The worm builds a calcareous tube within the living coral.
Tank requirements
- Minimum tank volume: 80 L (mature reef with a healthy host coral)
- Temperature: 24-26 °C (75-79 °F)
- pH: 8.1-8.4
- Salinity: 1.024-1.026 SG
- dKH: 8-11
- Adult body size: 1-4 cm; Wikipedia reports body length about 3.8 cm and a tube up to 20 cm
- Lifespan: 5-30 years
Diet
It is a filter feeder. Per Wikipedia the radioles filter microorganisms from the water, which are deposited straight into the worm's digestive tract. In aquariums survival depends on a healthy living host coral and a plankton-rich water column with supplemental fine foods.
Compatibility
Peaceful and reef-safe. Avoid hawkfish and some wrasses, which may pick at the retractable crowns. The long-term success of the worm is tied to the health of its host coral, making it an advanced animal to maintain.
Breeding
It is a broadcast spawner; per Wikipedia it reproduces by casting eggs and sperm into the water. Captive breeding is not practical in home aquaria.
Spirobranchus giganteus Breeding Guide
Overview
Spirobranchus giganteus, the Christmas tree worm, is a small serpulid polychaete that lives embedded in living coral heads, particularly Porites and brain corals, occurring from the Caribbean to the Indo-Pacific. Its body reaches about 3.8 cm, while the calcareous tube it secretes can extend up to 20 cm into the coral. Two spiral, Christmas-tree-shaped crowns of brightly coloured radioles filter microorganisms from the water for feeding and respiration.
Reproductive Mode
There are both male and female Christmas tree worms, and they reproduce as broadcast spawners, casting their eggs and sperm into the water for external fertilisation. No asexual reproduction is documented for this species in the consulted source.
Sexual Reproduction
The fertilised eggs develop into larvae that subsequently settle on coral heads and then burrow into the coral to form their tubes. Settlement onto living coral is therefore an obligatory step in the life cycle, tying recruitment directly to the presence of a suitable host.
Common Challenges
Because the larvae must settle into and bore into a living host coral, Spirobranchus giganteus cannot be cultured without that coral, and there is no practical route to breeding it in a home aquarium. Specimens are collected and sold within a fragment of their host coral, and the worm's survival depends on keeping that host coral alive.