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Date: | Mon, 11 May 2009 20:35:32 +1200 |
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Cypraea shells are very smooth (a few genera in the family are not
smooth), and I expect that, combined with the shells' rounded
contours, this is a trait evolved to cause crab chelae and fishteeth
to slip off the shell, reducing the likelihood of shell-crushing
occurring. The labral denticles ("teeth") don't appear to have any
obvious function; a thickened labrum (outer lip) will resist
crab-peeling as well without them. I suspect that if they ever did
evolve to fulfill a function, their continued presence is merely
genetic inertia.
As to the idea of their helping the animal burrow, I seriously doubt
it. The columellar muscle is more than sufficient to keep shell and
animal together.
--
Andrew Grebneff
Dunedin, New Zealand
Fossil preparator
Mollusc, Toyota & VW van nut
<[log in to unmask]>
--
Andrew Grebneff
Dunedin, New Zealand
Fossil preparator
Mollusc, Toyota & VW van nut
<[log in to unmask]>
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