Hi Olev,
It is my experience also that only pectinariids will build very neat
cones. These are single-layer, smooth 'brick-wall' tubes of cemented small
particles.
However, I wonder if the rarer offshore pectinariids will be more variable
in their tubes than the 'ice cream cone' constructions we see from
well-sorted sandy beaches. I have some specimens I identified as Petta
assimilis McIntosh which have (I noted) "Tube near straight, is thick, not
a single layer, made of small grains, with larger foraminifera etc
attached. There is a inner brown secretion layer." Also an unnamed
pectinariid with "tube of large white, yellow and pink carbonate
particles, overlapped, (tiled and ca. 2 mm dimensions)."
So multi-layered and tiled pectinariid tubes are also possible.
Geoff
On Tue, October 16, 2012 10:46 pm, Olev Vinn wrote:
> Dear Geoff,
>> Thanks for the reply. The fossil in question is old indeed and probably
> belongs to pectinariids. It is from the Late Cretaceous of Colombia (South
> America). I copied all the answers I got, as they were very helpful. Now
> other list members will see them too:
>> -----------
>> Since I have not seen all the message people sent you as answer, maybe you
> just know my comments. Tubes from these two families are very easily
> recognized because Pectinariidae ones are rigid, cone-shape opened in both
> sides and somewhat straight. The size grain depends on the availability
> from environment, as well as for Terebellidae, but the way pectinariids
> attach the grains is different, because the tube finished as a brick wall,
> with almost all the grains in the same size. Finally, these tubes could be
> found inside the sand, in seagrass or just bottoms compound only by sand.
> I have attached to this message a figure I prepared for a chapter about
> pectinariids from Mexico.
>> On the other hand, terebellid tubes are made by any material from the
> bottom, from coralline algae, foraminifers, coarse grains, to seagrass
> roots, depending of the species. Nevertheless, It is not possible to
> identify terebellid species just by their tubes. Only the genus
> *Lanice*has some filaments in the upper part, for placing their
> tentacles as a net.
> Al the tubes are irregular found inside the sand in non-compacted bottoms,
> or below rocks. Consistency of these tubes are more weak than those from
> pectinariids. They are easily separated from the rock, and broken just
> with
> our fingers. I am attaching one photo of *Loimia* from Mexican Caribbean.
>> I suppose people has told you all this, but, anyway, I wanted to tell you
> what I know from them.
>>> Mario H. Londoño Mesa
> Instituto de Biologia
> Universidad de Antioquia
> Medellin, Colombia
>> ---------------------
>> Pectinariid tubes are always cemented sediment grains whereas terebellids
> have a proteniaceous matrix upon which sediment particles might be
> incorporated
> into, but never cemented. The other difference lies in the inner layers
> and this
> could be more useful for fossils, pectinariid tubes are very smooth (and
> straight
> but conical), whereas terebellid tubes are not polished inside and very
> rarely
> straight (like in Lanice).
>> Sergio Salazar
>> ----------------------------------------------
>> My post graduate student Tanya Scherbakova (she had started her project
> as a master-student) is an investigation of ultrastructure of various
> polychaete tubes. She already worked out a preliminiary classification
> jf polychaete tubes, base on the types of fixation of sand/mud particles.
> She uses SEM and some ofther techiques, like tomography.
>> I will ask her. But problem, that we have rather llimited material in the
> solid tubes of Terebellidae:
> Pista ( Axionice) maculata and Pista flexuosa. Other Terebellidae in
> our
> disposal, have the very soft tubes, consisting of inner thin organic
> cylinder and thick layer of mud particles,
>>> Alexander Tzelin
> ---------------------------
>> Pectinariidae tubes (based on extant species) are constructed very
> precisely with
> grain sizes nearly identical in size and cemented in a very orderly
> manner. Tubes of
> terebellid species that use materials other than sand are more random in
> their
> design, using almost anything available to construct the tube. Terebellid
> tubes are
> very well designed, but I do not believe even in the fossil record (using
> today's
> species as examples), one could not identify a pectinariid tube from a
> terebellid
> tube. Please send me a picture of your fossil tube if possible. I hope
> this helps.
>> Steve Gardiner
>> --------------------------------------
>>>>> I should have liked to learn from these fossil tube experts. Public
>> answers are more useful than private ones.
>>>> FWIW my suspicion as a non-expert on fossil tubes would be - modern
>> tubes
>> or fragments can be recognised as pectinariid, fossil tube fragments
>> perhaps. But a quick look suggested the oldest pectinariid fossils
>> reported were only Miocene.
>>>> Geoff
>>>> On Tue, October 16, 2012 3:50 am, Olev Vinn wrote:
>>> Thank you very much to all who helped me with morphology of
>>> pectinariid-terebellid tubes.
>>>>>> Olev
>>>>>>> Dear annelidans,
>>>>>>>> I am currently studying a pectinariid-like agglutinated fossil tube
>>>> from
>>>> the Cretacous. I asking your help regarding the possible morphological
>>>> difference between the agglutinated tubes made by Pectinariidae and
>>>> Terebellidae. Is it possible to distinguish Pectinariidae tubes from
>>>> Terebellidae tubes, based only on the tube?
>>>>>>>> Best wishes,
>>>>>>>> Olev
>>>>>>>>>>>> --
>>>> Dr. Olev Vinn
>>>> Department of Geology
>>>> University of Tartu
>>>> Ravila 14A
>>>> 50411 Tartu
>>>> Estonia
>>>>>>>> Tel./Fax +372 7 375 836
>>>> E-mail: olev.vinn from ut.ee>>>>http://www.ut.ee/~vinn>>>>>>> --
> Dr. Olev Vinn
> Department of Geology
> University of Tartu
> Ravila 14A
> 50411 Tartu
> Estonia
>> Tel./Fax +372 7 375 836
> E-mail: olev.vinn from ut.ee>http://www.ut.ee/~vinn>>
--
Geoffrey B. Read, Ph.D.
8 Zaida Way, Maupuia
Wellington, NEW ZEALAND
gread from actrix.gen.nz
