The feather duster
It's not everyday you stumble upon a field of feather dusters. What? Feather dusters? Yep. The Northern Feather Duster Tube Worm to be more specific. Found, in this instance, on a deep wall on Steep Island, just outside of Campbell River.
Steep is a fantastic dive site, presuming you have a skipper that can read the fast currents and drop you in the water at a safe, and fun time. The dive begins in 60 to 100 feet, a section of the vertical wall covered with tube worms. Now tube worms can be found in other sites throughout BC (in fact, from Alaska to California), but this is the only place I have seen, or heard of, where they are in abundance locally. This entire section of wall is covered with them. Large clusters of these 2 inch diameters worms, consisting of a long light grey tube around 30 inches, into which the purple feather duster-like plumes, called radioles, retract.
The species is highly light sensitive and will withdraw quickly into the tube if a shadow passes over it. Its blood contains chlorocruorin instead of hemoglobin and they can regenerate their plumes if a predator nips them off.
The radioles contain a 'food groove' that serves as a size-filter. The smallest particles, which fit in all the way to the bottom of the groove, are usually eaten. Moderate size particles, in the upper parts of the groove, are often glued together to build the tube. The largest particles, too large to fit within the groove, are usually rejected. The radioles are also used for gas exchange, like gills.
The tube worms are also great cover for a range of marine life, with puget sound king crabs and ling cod often seen resting within, or on the worms.
From a divers perspective, the tube worms offer a feeling of being somewhere otherworldly. A dive on the Steep Island tube worms feels like a deep dive in the middle of the ocean. It feels like you are visiting the Mid Atlantic Ridge, or the moon of Europa.
It's otherworldly atmosphere may be why it's influence is noticeable in Avatar. The scene of Jake Sully touching plants in the Pandora jungle, that promptly retract into tubes - these are basically tube worms!