Carole,

From Chapter 29 of "The Mollusks: A Guide to their Study, Collection, and
Preservation":

29.2.6 Annelida. Almost all segmented marine worms (annelids, phylum
Annelida) are polychaetes and occupy a great variety of habitats. In
comparison to other annelids, polychaetes have high species diversity and
many different body morphologies. Some polychaetes build and live in a
variety of tubes. Two families of polychaetes, the serpulids [e.g.,
Serpula vermicularis Linnaeus, 1767 and Spirobranchus giganteus (Pallas,
1766)] and spirorbids (e.g., Spirorbis bifurcates Knight-Jones
1978)] produce calcium carbonate tubes (Figure 29.6), which are cemented
on rocks and other hard surfaces. Polychaete tubes are secreted by a pair
of large glands near the base of the worm’s crown. These tubes are
sometimes misidentified as tubes belonging to small vermetid snails.

In general, tubes from vermetid snails are calcareous, three-layered
tubes, with the inner layer being glossy. There may be a spiral protoconch
present. Often there is a spiral (appears longitudinal) or a cancellate
pattern to the shell’s surface. Polychaetes build two-layered tubes of
unadorned mud, sand, or parchment (often decorated with sand, shell
fragments, algae, or hydroids) or of hardened calcium carbonate. A live
vermetid snail will often have an operculum at the opening of
the tube, whereas a tube-dwelling polychaete may have a funnel shaped
operculum that arises from a modified radiole (Keen 1961, ten Hove 1994).

As tube dwelling polychaetes, both serpulids and spirorbids bear a
tentacular crown, as in feather duster worms, in addition to a
funnel-shaped operculum that can be pulled into the end of the small
calcareous tube when the worm withdraws. Serpulids form moderately
straight tubes whereas spirorbids form tubes that coil to the right
(dextral or right-handed) or left (sinistral or left-handed). In Hawaii,
sea frost that occurs in tide pools, deeper reefs, and on harbor pilings
is actually masses of white intertwining tubes of the serpulid Salmacina
dysteri (Huxley, 1855) (Hoover 1998).


> Good morning all, praying our Carolina / Georgia friends and all our
> Jacksonville friends are not devastated by Matthew. Please Harry, Bill,
> Everett,
> Jean and all, let us know you are all right and if there is any way we can
> help.  I have an extra room if needed.
>  To keep on topic, does anyone know how to tell the difference between
> worm tubes and mollusk worm tubes. There is a small esoteric worm called
> Thylaeodus, I am told lives in my Peanut Island area. I see a lot of
> little
> white tubes with longitudinal lines, but I am not sure if they are
> mollusks or
> worms. I did find one on a Spondylus, that I am sure of, but not sure
> where
> the  Spondylus is exactly from. I know it is S. Florida.
> Can anyone tell me more about these?
>  Carole
>
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Regards,
Charlie
.................................................
Charlie Sturm

Treasurer
American Malacological Society

Research Associate - Section of Mollusks
Carnegie Museum of Natural History
Pittsburgh, PA, USA

Associate Professor - Family Medicine
Fellow-American Academy of Family Practice
Fellow-Academy of Wilderness Medicine

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