A sac-shaped worm in a burrow, known by the long forked proboscis it spreads over the sand.
The animal itself is a soft unsegmented sac, sausage-shaped and to about 15 cm, and it stays in a burrow in sand or under rubble where it is effectively never seen. What is seen is the proboscis: a flat, mobile, grooved extension of the head end, forked at the tip in many species, that is pushed out across the sediment surface and spread over it. Extended it commonly reaches ten to thirty centimetres, several times the length of the body, and it is pink, grey, fawn or green.
Feeding works along that surface. Cilia and mucus move particles down a groove on the underside of the proboscis to the mouth at its base, the proboscis sweeps a patch of sediment clean and is then drawn back and pushed out in another direction. Withdrawal is quick at any disturbance, and once the proboscis is in there is no sign left on the surface at all.
It is regularly recorded as a flatworm, a ribbon worm or the feeding tentacle of a buried sea cucumber. The distinctions that hold are that the whole structure issues from a single point in the sediment and is drawn back into it, that it is one broad ribbon rather than the many fine threads a spaghetti worm puts out, and that it has no eyes and no defined head. Recorded from about 3 to 30 m.
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.
