Pig Butt or Marine Worm?

From MBARI: This is a worm? This photograph of the newly named worm shows its mouth, which typically faces downward as the animal drifts about 1,000 meters (3,300 feet) below the ocean surface. Image: Karen Osborn (c) 2006 MBARI

The picture is of a new marine worm, Chaetopterus pugaporcinus, that dwells at 1000m.  Its Latin name translates into "Chaetopterid worm that looks liek th rump of a pig.  It has a segemented body like other polychaetes but the middle segments are inflated.  The posterior and anterior segments are compressed against the inflated segments.  One of the authors, notes its similarity to the larvae of other chaetopterid worms with the exception that is 5-10x larger, so it may be an adult.  On the other hand none of the individuals yet identified have sex organs, sperm, or eggs, so it may be a larvae.  By the way, that family of worms is a taxonomic mess, so before the authors could place this worm in the family, they had to construct a phylogeny to sort out the mess.  The worms feed by facing mouth down and deploying a mucus cloud that catches marine snow. More pictures below fold. More at MBARI. 

This photograph shows the back of the newly named worm. The concentric ovals are body segments that have been flattened against a single central segment that has ballooned out to form the bulk of the the worm's body.Image: Karen Osborn (c) 2006 MBARI

This beautiful photograph shows a "normal" chaetopterid worm larva, with its elongated, segmented body. Many chaetopterid worms spend months as drifting larvae. Image: Karen Osborn (c) 2006 MBARI

This photograph shows another view of Chaetopterus pugaporcinus, including its mouth parts.

Image: Karen Osborn (c) 2006 MBARI