All that shows on the sand is a mat of white feeding tentacles; the worm is below.
A terebellid worm living head-down in a mucus-lined tube in soft sediment. What is visible is a spreading mat of fine white to pink tentacles, radiating over the surface for up to half a metre, moving slowly and independently of one another; the worm itself is buried and is almost never seen. Each tentacle is grooved and ciliated and carries collected particles back to the mouth along the groove, so the mat is a feeding apparatus laid out over the sediment surface.
It is one of the animals that makes a stretch of grey silt worth looking at. The tentacle mats are a landmark on a muck site, and small commensals — shrimps, tiny crabs, occasionally a juvenile fish — use them for cover. Tentacles detach readily when pulled and regrow, and a diver’s fin wash will clear a mat that took an hour to lay out. Recorded from the shallows to about 30 m. The photograph is a study in texture rather than in an animal, which is why it is more often walked over than taken.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.
