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| Date: | Fri, 12 Oct 2001 13:52:31 +1300 |
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Hi everyone and thanks for all the responses:
There appear to be many unbelievers that hermit crabs damage the shells they
live in. I too have collected many specimens occupied by hermit crabs while
in the Pacific and many do not display damage - maybe damage is time and
taxa related. Let me use Neritidae as an example. In my experience (and in
many of my archaeological samples) the edges of the aperture have been
dissolved; ie the columellar pad has been partially etched or abraded away
as well as any denticles on the opposite side of the aperture. It is in
this way that the aperture is widened without literally breaking the
aperture or chipping it back. This is certainly not the doing of the
mollusc and seems an unlikely wear pattern in relation to beachrolling and
other intertidal action. I can only tie it sensibly to hermit crabs.
Although most obvious often in Neritidae, similar damage is often seen in
Planaxis sulcatus, various thaids and turbinids etc.
With regards to the columella, it is frequently absent, or present only
in remnant form in specimens that have the greatest degree of aperture
damage. This also is clearly not caused by the mollusc and the absence of a
columella when the rest of the shell is largely in tact is an odd thing
indeed - though very common in the samples I look at.
Hermit crabs are the only feasible explanation I can see to explain this
sort of damage - though perhaps terrestrial rather than intertidal hermit
crabs (?). This sort of damage has been reported in relation to Coenobita
rugosus (Carucci 1992; Kinosita and Okajima 1968:296).
Have I been vindicated for my choice of indicators?
Kath.
<br><br><br><html><DIV>Katherine Szabo </DIV>Archaeology and Natural History
<DIV></DIV>Research School of Pacific and Asian Studies
<DIV></DIV>Australian National University
<DIV></DIV>
<DIV></DIV>Canberra ACT 0200
<DIV></DIV>Australia
<DIV></DIV>Ph:61-2-6125 2235
<DIV></DIV></html>
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