>Hello
>I searched the Internet for over one hour for info. on Nautilis
>pompuilis.  How does the shell go up and down in the water column?
> What gas is used tin the chambers?  What is the sphical (the tube)
>running through each chamber used for?  A friend of mine is
>wondering and my knowledge of the subject is not "tangible" and I
>would like it to be written or readable on the computer screen.
> Thanks in advance (I always forget to say that).
>
>J. Star

The shell rises and falls very slowly (if the animal is rendered
excessively buoynatt by removing a chunk of shell lip, for instance,
it can take hours to resubmerge); the siphuncle acts as an osmotic
pump, removing water (not seawater, note) from the chambers and
replacing it with basically air or vice-versa; both fluids I think
are derived from the bloodstream.

For details see:

Ward Peter D "The Natural History of Nautilus", Allen & Unwin,
ISBN 0-04-500036-0. Your town library may well have a copy.

Ward, P D 1988 "In Search of Nautilus", Simon & Schuster, ISBN 0-671-61951-9

And various papers by Ward and Bruce Saunders, some in collaboration.

By the way, Neil Landman (with whom I am supposedly working on a
paper on NZ middle Triassic ammonoid aptychi) tells me that
Cenoceras, a late Triassic-Jurassic nautiloid genus in family
Nautilidae, is probably a synonym of Nautilus. If so, this extends
Nautilus' fossil range WAY back from the Oligocene. It also means
that Eutrephoceras, a Cretaceous-Cenozoic nautilid, also must be
synonymized with Nautilus (and not before time); also the
recntly-described Allonautilus ditto.

I have thought for some time that there is almost nothing to separate
NS's late Triassic Cenoceras trechmanni from Allonautilus
scrobiculatus on conchological characters.

On top of that, I think that Cymatoceratidae, a family of
Cretaceous-Cenozoic nautiloids bearing chevron (tractor-tire) ribs on
the venter, properly belong in Nautilidae.
--
Andrew Grebneff
165 Evans St, Dunedin 9001, New Zealand
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