In the context of presumed longevity records, it has been suggested to
look for data available from sponges and corals.
Yes, considerable longevity can be expected for some organisms of
these groups in deep water.
SPONGES
Vacelet J., Cuif J.P., Gautret P., Massot M., Richer de Forges B.,
Zibrowius H., 1992. Un sphinctozoaire colonial apparente aux
constructeurs de recifs triasiques survivant dans le bathyal de Nouvelle-
Caledonie. Comptes-rendus de l'Academie des sciences, Paris, Ser. 3,
314 (9): 379-385.
(here without French accents because of possible transmission
problems; title was also given in English translation: A colonial
sphinctozoan sponge related to Triassic reef builders surviving in deep
water off New Caledonia)
Well, "colonial" in that case may deserve another discussion. The term
was used because of the growth mode, distinguishing this Recent deep
water sphinctozoan from a previously known species (cryptic in shallow
coral reefs) because it is branched and able to produce aggregates.
What is of interest here, is that by isotopically dating the base of a living
10 cm aggregate an age of 700 years was found.
SCLERACTINIAN CORALS
First, Daniel Martin's remark: "Although there are some solitary corals,
these organisms are probably the best known example of colonial
animals."
In fact not only some, but hundreds of species of solitary scleractinian
coral species do exist, all over the range of this group (from the edge of
Antarctica to Greenland and Norway, from the tidal zone to some 6000m)
However, the distinction solitary vs colonial has not been taken into
account in a recently published evaluation of scleractinian species
richness (1314 species listed - all these are CITES protected thanks to a
bunch of brain-deficient bureaucrates).
Cairns S.D., 1999. Species richness of Recent Scleractinia. Atoll
research bulletin, 459: 1-46 (includes: Cairns S.D., Hoeksema B.W.,
Land J. van der, Appendix: List of extant stony corals, p. 13-46).
As for old age of a solitary scleractinian, it has been speculated that a
single polyp of Desmophyllum cristagalli may have lived up to hundreds
of years in order to produce an extremely massive skeleton 12 cm high
and some 700 g in weight. This specimen was taken (already dead) by a
fisherman in deep water of Bjornefjorden, Norway, and is deposited in
the Bergen museum. With modern methods using small amounts of the
skeleton (to be obtained by boring at different levels, thus essentially not
destructive) it should be possible to verify that speculation.
The main argument in this case for suggesting an extended longevity, is
the amount of energy needed (in addition to that needed for the other life
processes) to have such a heavy piece of calcium carbonate built up by
a watery polyp.
Zibrowius H., 1980. Les scleractiniaires de la Mediterranee et de
l'Atlantique nord-oriental. Memoires de l'Institut oceanographique,
Monaco, 11: 284 p., 107 pl.
Helmut ZIBROWIUS
(Centre d'Oceanologie de Marseille)
Station Marine d'Endoume
Rue Batterie des Lions
13007 Marseille / France
E-MAIL: hzibrowi at com.univ-mrs.fr
TEL: within France 0491041624 from abroad +33 491041624
FAX: within France 0491041635 from abroad +33 491041635
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