Spirobranchus giganteus

Christmas Tree Worm

The feathery tentacles of the spiral crowns function both as filter-feeding mechanism and respiration. Photo by Ana Robles Cortez, 2017.

  • Kingdom Animalia
  • Class Polychaeta
  • Order Canalipalpata
  • Family Serpulidae
  • Genus Spirobranchus
  • Species S. giganteus

S. giganteus is a tube-building Polychaeta worm which lives primarily on large stony brain corals and porites. The distinct feature of this animal is it's brightly colored crown spirals which come in pairs.

Each spiral is composed of 'radioles', the feather-like tentacles which are covered with mucus and hair-like 'cilia'. This structure helps in trapping passing prey by pumping the water from below into a column which is then conveyed to its mouth. Not only do they filter micro plants and animals for feeding, the spirals double as a respiratory organ by harvesting oxygen from the water.

The average size of the spiral crowns are about one inch with two-thirds of the worm lying inside it's calcerous tube in the form of a tubular segmented body. The body is lined with small appendages called 'chaeta' which aid in mobility. When the worm withdraws into the tube, another specialized body part, known as the 'operculum' closes the hole like a lid.

The species is well distributed throughout tropical oceans worldwide. They are commonly seen living in shallow water as deep as 30 meters and can live up to 30 years.