In the original email message "handedness" is related to temperature, not
genetics. The Kucera and Kennett paper divides Neoglobroquadrina
pachyderma into six species, four of which have been described in recent
years (one new in the paper cited). So the "handedness" reflects different
species, not different forms of the same species.
Best,
Chuck
Charles L Powell, II
Western Earth Surface Processes Team, MS 975
U. S. Geological Survey
345 Middlefield Rd.
Menlo Park, CA 94025
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(650) 329-4985
"Monfils, Paul"
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Sent by: Subject: Re: Foram "handedness" was Re: fake shells... the Cebu Shell Dakt
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01/06/05 11:19 AM
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Not sure what you mean by "completely genetic". What cause other than
genetic would "handedness" be due to?
Paul M.
> ----------
> From: Charles L Powell
> Reply To: Conchologists List
> Sent: Thursday, January 6, 2005 10:07 AM
> To: [log in to unmask]
> Subject: Foram "handedness" was Re: fake shells... the Cebu Shell
> Daktari strikes!
>
> Not directly mollusk related, but planktonic foraminiferal "handedness"
> may
> be completely genetic as the different "forms" are now being assigned to
> different species. See Kucera, M., and Kennett, J.P., 2000,
Biochronology
> and evolutionary implications of late Neogene California margin
planktonic
> foraminiferal events: Marine Micropaleontology, v. 40, p. 67-81.
>
> Best,
>
> Chuck
>
> Charles L Powell, II
> Western Earth Surface Processes Team, MS 975
> U. S. Geological Survey
> 345 Middlefield Rd.
> Menlo Park, CA 94025
> [log in to unmask]
> (650) 329-4985
>
>
>
> Andrew Grebneff
> <[log in to unmask] To:
> [log in to unmask]
> TAGO.AC.NZ> cc:
> Sent by: Conchologists List Subject: Re:
> fake shells... the Cebu Shell Daktari strikes!
> <[log in to unmask]>
>
>
> 01/05/05 03:58 AM
> Please respond to
> Conchologists List
>
>
>
>
>
>
>
> > However, mollusks are relatively unusual in having many kinds that
> >are normally distinctly asymmetric. Many forminifera have
> >snail-like coiled shells; these can be sinstral or dextral, too.
>
> Foram handedness is temperature-controlled, with no genetic
> component, and is unrelated to gastropod coiling. Indeed, the
> organisms (currently in kingdom Protists, so they are not animals or
> "creatures") themselves are basically "amorphous" blobs of protoplasm
> & organelles. I wonder how they manage to secrete such regular and
> beautiful shells?
>
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