Feather-duster worms

Taxonomically, the feather-duster tubeworms (Family Sabellidae) of the Pacific Northwest are in a state of flux because many species descriptions are based on specimens of European worms that may or may not exist along this coast. Gradually, research and new descriptions are determining the true identity of species in this group. As seen in the photographs, the feather-duster tubeworms are diverse. Their size range is also extreme, from less than 1 cm (0.4 in) to 2.1 m (7 ft)! The similarity of the tentacular crown structure and the household “feather duster” appears to be the common name’s origin. To varying degrees, the tentacular crown (plume) serves the dual purpose of respiration and filter feeding, similar to the calcareous tubeworms, p. 147. The crown is bilobed and the spoke-like tentacular radioles (branches) that extend from each lobe have tiny lateral branches called pinnules. Feather-duster tubeworms have as few as two pairs of radioles to several hundred pairs. Both radioles and pinnules are grooved and ciliated. The cilia (hairs) effectively aerate the blood by circulating water up through the plume, while at the same time filtering out food items such as unicellular algae and planktonic larvae. Once captured, the food moves down the grooves of the radioles to the mouth. The feather-duster tubeworms have an amazing ability to sort and select particles by size, some obviously for ingestion and others for tube-building material. The action of giant nerve fibres within the ventral nerve cord enables these worms to retract inside their tubes rapidly when disturbed.