Re: NANFA-- Osmoregulation in freshwater sharks

Bob Bock (bockhouse_at_earthlink.net)
Sun, 20 Jan 2002 20:56:18 -0500

Are you sure? I just read about this today, in Fish Anatomy, Physiology, and
Nutrition, p. 61, "The combination of salts at concentrations siimilar to
those in bony fishes and nitrogenous waste products increases the osmotic
concentration of the blood so that it is slightly hypertonic to the
seawater."
----- Original Message -----
From: "Bruce Stallsmith" <fundulus_at_hotmail.com>
To: <nanfa_at_aquaria.net>
Sent: Sunday, January 20, 2002 7:43 PM
Subject: Re: NANFA-- Osmoregulation in freshwater sharks

> >FYI, Jeremy, unlike marine bony fishes, sharks have a higher blood ion
> >concentration 2 percent, as opposed to about .2 percent in the bony
fishes.
> >This higher concentration is due to urea, which would kill bony fishes in
a
> >concentration so high.
> Urea is present in high concentration, but so is another organic salt,
TMAO,
> which is usually found in a concentration of 2:1 relative to the urea.
This
> enables sharks to be isotonic (roughtly same salts concentration) relative
> to sea water and eases osmoregulatory pressures.
>
> (10 years ago I could have told you off the top of my head what TMAO
stands
> for...).
>
> --Bruce Stallsmith
> Huntsville, AL, US of A
>
>
> _________________________________________________________________
> Chat with friends online, try MSN Messenger: http://messenger.msn.com
>
>
>
/---------------------------------------------------------------------------

--
> /"Unless stated otherwise, comments made on this list do not necessarily
> / reflect the beliefs or goals of the North American Native Fishes
> / Association"
> / This is the discussion list of the North American Native Fishes
Association
> / nanfa_at_aquaria.net. To subscribe, unsubscribe, or get help, send the word
> / subscribe, unsubscribe, or help in the body (not subject) of an email to
> / nanfa-request_at_aquaria.net. For a digest version, send the command to
> / nanfa-digest-request_at_aquaria.net instead.
> / For more information about NANFA, visit our web page,
http://www.nanfa.org

/----------------------------------------------------------------------------- /"Unless stated otherwise, comments made on this list do not necessarily / reflect the beliefs or goals of the North American Native Fishes / Association" / This is the discussion list of the North American Native Fishes Association / nanfa_at_aquaria.net. To subscribe, unsubscribe, or get help, send the word / subscribe, unsubscribe, or help in the body (not subject) of an email to / nanfa-request_at_aquaria.net. For a digest version, send the command to / nanfa-digest-request_at_aquaria.net instead. / For more information about NANFA, visit our web page, http://www.nanfa.org