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To: shelps@ac*.ma*.ad*.ed*.au* (Prime Rat)
To: <RLaird@pe*.co*>
Subject: Re: movement through water
From: scot@bt*.co* (Scot Anderson)
Cc: techdiver@opal.com
Date: Wed, 11 Jan 95 20:00:47 EST

At 11:30 95/01/12 +1030, Prime Rat wrote:
>
>>   >A swimming tail is not only less efficient for straight line travel it is 
>>   >horrendously complex compared to a propeller.  
>>
>>Why is it less efficient?  
>Temperature is a problem fish have with their energetics.  I believe Tuna 
>solve this by being warm blooded but then, they are voracous feeders as 
>well.  Comment from the icthyologists?

Tuna do that through something called "rete mirabilia" (spelling escapes me) -
that is, an heat exchange mechanism between blood exiting and entering the
gills.  Blood leaving the core muscles goes through
an elaborate capillary network interleaved with blood exiting the gills. 
This warmer blood, in close proximity to the cooler blood returning from
the gills, warms it.  Hence their cruising muscles remain a little
warmer than the surrounding liquid.   Tuna isn't the only one, either...
p.s. this is NOT "warm blooded".  

Scot Anderson          <scot@bt*.co*>          http://www.btg.com/~scot/

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