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SWIMMIN' CRITTERS..



> On Fri, 17 Nov 1995 GSP1954@aol.com wrote:
> 
> > Concerning swimming theropods -
> > 
> > Most animals are good swimmers. 
> [...]
> > probably better swimmers than birds, but not as good as crocs. This does not
> > mean they were specialized swimmers, just that they could when needed, and
> > were able to pursue prey into the water (like some living big carnivores 
> > do).
> 
> This is true....armadillos are another good example of this. They aren't 
> naturally aquatic, but have been observed fording ponds, streams, and 
> other moderate bodies of water when they have to. They can also submerge 
> for up to 30 mins. on a breath when necessary. Again, this doesn't mean 
> they *LIKE* to, just that they can...
> 
> 
> -----Steve

An interesting area (armadillos) - in reading around for this, I had a
couple of people tell me that armadillos couldn't swim! The main idea is
that they are too heavy - an argument that has also (laughably - but
seriously!) been directed at elephants! Anyhow, armadillos have a higher
specific gravity than water, and sink. This isn't a problem - they are
adapted for burrowing and rely on anaerobic respiration more than
'average' - they can hold their breath for rediculously long amounts of
time (as Steve says). So, down they sink to the bottom, and then trot
along  on the river/lake bed. This is slow, however, and sometimes they 
seem to prefer surface swimming. The method bu which they achieve this is
fascinating, and succinct. They 'swallow' air, inflating their stomachs 
and guts, and can then float on the surface. I've also been told that they then
re-cycle this air as it leaves the gut, to aid in a primitive form of
jet propulsion.. but I'm perhaps a little dubious of this suggestion.

In fact, aside from the specialized land birds (hummingbirds, swifts,
swallows, martins, colies all being good examples), unfairly
mutated domestic dogs, and pathetic humans, all tetrapods are competent
swimmers. I haven't yet found a source saying whether or not testudinid
turtles can swim - I know they float - and my humane (very ironic word)
ideals prevent me from undergoing any attempt at practical
demonstration.

What glyptodonts would have done to swim I wonder - I shouldn't think
they'd have that much of a problem however. Likewise with ankylosaurs -
but is s.g. that much of a problem? Any helpful comments appreciated.

"Jack - I know how you feel"

DARREN NAISH