Re: Sclerotic rings

[christopher robert noto <crnoto@midway.uchicago.edu>]

John,
If I'm not mistaken, that is not the only explanation for sclerotic rings
in marine reptiles.  At least in Ichthyosaurs, sclerotic rings probably
helped maintain the shape of the eye when swimming at speed, as opposed to
protecting the eye at depth.  Squid have large eyes, but I don't think
they have rings in them and they do live at depth, bu then again they
don't have to surface so there's no pressure difference.  Also,
cetaceans have extremely small eyes proportional to their body size,
which may affect such things.

Check out any of the recent articles by Motani for more information, he
also has a website on the subject at

http://www.ucmp.berkeley.edu/people/motani/ichthyo/index.html

look at "Eyes of Ichthyosaurs".

hope this helps,
Chris


On Thu, 5 Apr 2001, John Fredriksen wrote:

> A question for all you mesozoic mavens out there.
>     Marine reptiles developed sclerotic rings around their eyes as a
> means of coping with high pressure during deep dives, correct? Well, do
> whales have such structures and, if not, how do they compensate for the
> pressure without ruining their eyes?
> 
> John
>