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Someone wrote:-
> A swimming tail is not only less efficient for straight line travel, it
> horrendously complex compared to a propeller.

Prime Rat replied:-
>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?

I saw an item about the artificial fish tail compared with a propeller, on a
UK TV program called `Tomorrow's World'. It seems that the fishtail sends more
water backwards and less sideways than the standard propeller. But it seems to
me that what you gain in efficiency this way you lose in payload and motor
space by the space occupied by the tail-waving mechanism. I suspect that most
research will have to be towards more efficient screws and waterjets etc.

> Tuna do that through something called "rete mirabilia" (spelling escapes me) -
> that is, an heat exchange mechanism ...

Singular `rete mirabile', plural `retia mirabilia', 3rd declension neuter.
I read somewhere that the great white shark is a bit warm blooded also.

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