Hi Geoff,
Thank you very much for the interesting information!
Olev
> 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>
--
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.eehttp://www.ut.ee/~vinn
