Metal transport (was: platoon stuff and combat engineers)

Beth, perhaps you can shed some light on this. Seems an appropo time to
bring it up.

on 02.6.26 1:34 PM, Beth.Fulton@csiro.au at Beth.Fulton@csiro.au
scribbleth:
> 
> After the last major comet collision the major herbivore niche was
empty,
> this allowed the shallow swamp dwelling snails to push further on
land. As
> they did this the developed desiccation resistant shells and egg
coatings
> (actually it was the other way round but there were no biologists
there to
> jot that down, but it has kept great swaths of academia locked in
perpetual
> uproar for a good part of 70 years now... 4 million years after the
event).
> The expansion in snail folivores meant that there was a large pool of
unused
> biomass allowing for the detritus feeding microwasps to extend their
nursery
> sites (they lay their eggs in their larvae's future prey) and increase
in
> size and brood size. Unfortunately as the wasps got more aggressive
and wide
> spread the snails needed thicker shells. They found the most efficient
way
> was to incorporate undigested and chemically processed ore particles
into
> the quinpartite structure of their shell matrix. The resulting history
of
> coevolution leaves us with the metali-snails and their oviparasitic
wasps on
> the tray in front of you. Have fun in the dissection and watch out not
to
> get any of the attachment sack on your fingers... or you'll find
yourself
> intimately attached to your dinner tray when you get to the dorms
> tonight....

Terran animals use stones for support, presumably because Ca-based
structures are relatively easy to form given water-based transport, and
Ca
is plentiful in the environment. While there are some snails (IIRC; I
think
you told me that, actually) that use Ti for an oxygen-transport
mechanism, I
don't know of any structural uses of metal or metallic compounds. Why
not?
Just because the useful metals are not as chemical active as Ca? (and
the
ones that are active aren't common) Fe seems to have plenty of useful
reactivity, considering we use it to transport O2 ourselves.

Are there are chemistry- or physics-related reasons why metal structures
aren't found in nature? (real answers, theories, sheer guesses and tall
stories all welcome)

-- 
Edward Lipsett
Intercom, Ltd.
Fukuoka, Japan
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