Re: insects - not! (OT)

[Phil Bigelow <bigelowp@juno.com>]

Gills are VERY efficient gas exchange organs on land, and upward
scaleability, per se, shouldn't be a problem.  The limiting factor is how
much water loss is acceptable with increasing gill surface area.  If the
Earth's atmosphere had always been saturated with water vapor (relative
humidity kept perpetually at 100%), then evolution of super-sized land
crabs (with huge external gills) could have occurred.

Think 100 Kg Robber Crabs with an attitude.  Snipping the legs off of
troodontids as they walk by.  Pleasant dreams, people!  ;-)

<pb>
--

On Mon, 02 May 2005 08:16:10 +1000 Dann Pigdon <dannj@alphalink.com.au>
writes:
> Phil Bigelow wrote:
> > 
> > The largest living "land" invertebrate is the Robber Crab.  Do a 
> Google
> > on it.
> > It spends a lot of its time hunting on land.  Getting enough 
> oxygen isn't
> > the limiting factor for big land arthropods.  Their problem is 
> keeping
> > their gills moist.
> 
> Not all crabs are dependant on water to breath. There's a species 
> of
> land crab that lives in the middle of the Australian desert. It 
> only
> encounters water on the rare occasions when it rains, then it 
> quickly
> breeds and lays eggs. It's dry the rest of the year (both the crab 
> AND
> the desert, that is).
> 
> Maitland, P. & D. Maitland, 1986. The Australian Desert Crab. A
> Side-walk to the conventional crustacean. Aust. Nat. Hist., 21(11):
> 496-498.
> 
> pheret wrote:
> 
> > i believe cockroaches have a similar breathing mechanism?  i 
> > know i read an article about their breathing which is not the same 
> as 
> > other insects
> 
> Cockroaches are amazing insects. They invented wing assisted 
> running
> long before any archosaur attempted it. When they have to go really 
> fast
> (and for their size they're the fastest runner known in the insect
> world), they actually run bipedally with their body shape acting as 
> an
> aerofoil to keep the front part of their body up.
> 
> -- 
> ___________________________________________________________________
> 
> Dann Pigdon
> GIS / Archaeologist         http://www.geocities.com/dannsdinosaurs
> Melbourne, Australia        http://heretichides.soffiles.com
> ___________________________________________________________________
> 
>