Sentence:  Family Sabellidae [...] Head with a characteristic crown of 2 groups of pinnate projections called <WSD>radioles</WSD> [...], which sometimes bear eyes, and project from the tube when the worm is feeding. 
Meaning of the word marked with <WSD> tags:  A heavily ciliated feather-like tentacle occuring in clusters on the crowns of certain tubeworms, especially those of the order Canalipalpata (the (fan-head worms)), used for feeding and respiration.