Calcareous tubeworms

Hard, rocky substrates tend to be the preferred sites for attachment of the calcareous tubeworms (Family Serpulidae), although various species also affix to algae and seagrasses, mollusc shells and arthropod exoskeletons. All calcareous tubeworms have tubes formed primarily of calcium carbonate and a matrix of mucus and carbohydrates. Specialized glands near their heads are responsible for tube production. When the mucus/carbohydrate mixture is secreted within the confined space of these glands, calcium carbonate is precipitated from the surrounding seawater. This mixture is then applied to the leading edges of the tubes. Consequently, as the worms grow, so do their encasements. The calcareous tubes immediately identify these worms and readily distinguish them from their close relatives, the feather-duster tubeworms, whose shelters consist of mucus/sediment combinations. As with the feather-duster tubeworms (AN60–67), the calcareous tubeworms have tentacular crowns that function in both feeding and respiratory activities. The tentacular crown is composed of two halves or lobes, each carrying a number of feather-like radioles (spoke-like branches), which have tiny lateral branches called pinnules. Calcareous tubeworms have as few as three pairs of radioles to 20 pairs or more. Most, but not all, calcareous tubeworms have the added benefit of an operculum (trap door) to seal off the tube entrance—presumably an anti-predator device. Each operculum is a transformed radiole (feather-like branch) of the tentacular crown and can be ornate, symmetrical or irregularly shaped, calcified or chitinized (tough, protective). Some species of calcareous tubeworms have achieved an economic status as significant fouling organisms on pilings, docks and boat hulls.


Apomatus spp. (Apomatus geniculata and Apomatus timsii)


Protula pacifica

AN52. RED-TRUMPET CALCAREOUS TUBEWORM, colourful calcareous tubeworm, calcareous tubeworm, calcareous tube worm, limy tubed worm, limy-tubed worm, white-tubed worm, red tubeworm, red tube worm, serpulid worm, fan worm, plume worm

Serpula columbiana*

AN53. THREE-BRANCH CALCAREOUS TUBEWORM, fragile tubeworm, fragile tube worm, orange tube worm

Salmacina tribranchiata, Salmacina dysteri tribranchiata


Pseudochitinopoma occidentalis, Chitinopoma groenlandica (in part)


Crucigera zygophora

AN56. DWARF CALCAREOUS TUBEWORMS, tiny tube worms, spiral tubeworms, spiral tube worms, small spirorbid worms, snail worms

Pileolaria spp.

Dwarf calcareous tubeworms, also known as spirorbids, have at times been considered a separate family but are included here as Serpulidae. Their systematic status is debated, but some 130 described species of spirorbids are recognized worldwide, 30 of which occur in the Pacific from Alaska to Panama. Many of these species can be expected to inhabit the Pacific Northwest.