Re: Tears and 'salt excretion'. Was Re: tears
Bill Burnett (bbur@wpo.nerc.ac.uk)
Wed, 1 Nov 1995 11:13:35
H. M. Hubey writes:
>bbur@wpo.nerc.ac.uk (Bill Burnett) writes:
>You can't
>>afford to waste water in a salty environment or you get dehydrated very
>>quickly.
>So?
>What do whales drink? Do they not drink for weeks at a time? Or
>maybe they swim up to rivers and then go upstream until there's
>no salt left in the river, drink and swim back to the ocean.
>How about seals? Where do they find water to drink? And how
>about the other critters like doogongs (sp?), walruses, sea
>otters.
>Do any of these animals swim in rivers?
Jim Moore has graciously saved me the trouble of how whales drink so I shan't
bother with that... Other than to point out that your 'drain and dilute'
ideas of isotonic excretory mechanisms could only work in freshwater so your
irony is self defeating...
Since you asked, plenty of these animals swim in rivers but I rather doubt
it's because they're thirsty... It's a relatively trivial matter for a marine
mammal to swim into freshwater compared with e.g. a marine fish, so they don't
need a major incentive to do so, although I've heard it suggested that
hypotonic river water is bad news for external parasites. Some of them live
there all the time, might be interesting to compare their kidneys with those
of habitually marine species.
And on a slight sideline...
I wrote...
>>the AAT 'becomes' unnecessary. Doubtless a return to the all mammals
evolved >>in water at 98.1F argument will be forthcoming from certain
quarters...
Which provoked the typical AAT advocate's response...
>Find a better explanation of evidence.
What 'evidence' are we talking about? I see another cute but unsupported
hypothesis. Since I'm not sufficiently desperate for an explanation to invent
one and carve it in stone to oppose you, you are obviously right and I concede.
>Ahhh, yes, the doubtless better explanation "It just happened by
>accident like everything in the universe! There's no direction to
>evolution. It just happens. Rocks fall down. Why? They just do
>Sea is salty. Why? It just is......."
What sort of direction do you want for evolution? Going to tell us you're
'higher' than a worm again? Richard Owen and victorian Britain thought
that, and Darwin and Huxley were trashing them 150 years ago, before the
'Origin' was even published. Ask Tom Clarke for a copy of Dawkins, there's no
need for a direction except human insecurity.
As for falling rocks and salty oceans I can only suggest Newton and a decent
physical oceanography text.
Bill
|