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.eehttp://www.ut.ee/~vinn
