To add to this, color is in the eye of the beholder. Insects can see
colors in flowers that we perceive as only white. If the predator has
more or less limited color vision then colors are more or less important
but the pattern remains important in disguise.  If a snail living in 200
ft of water only wants to produce a pattern  of light and dark patches,
the dark patches can be almost any color other than blue or white.
 
Russ
 
 
 
 
> ----------
> From:         Paul R. Monfils[SMTP:[log in to unmask]]
> Sent:         Wednesday, February 04, 1998 6:30 PM
> To:   [log in to unmask]
> Subject:      Re: Seeing color
>
> Hi Art and all,
>
> The question is not really whether color can be perceived at depths in
> the
> ocean.  The fact is, there is nothing there to be perceived.  Color in
> its
> essence consists of specified wavelengths of electromagnetic
> radiation, in the
> waveband we call visible light.  In the absence of light, there is no
> color.
> Color, as we refer to it in an object or a substance means the ability
> of the
> object to reflect those specified wavelengths of light; and color
> perception
> means the ability to visually (or otherwise) detect those reflected
> wavelengths.  At more than a few meters depth in ocean water, there is
> no way
> that anyone or anything can detect red light by any means, because
> there
> simply is no red light present - the red wavelengths are all absorbed
> in the
> first few meters of water.  Therefore nothing can look red to the eye
> or to a
> camera.  A red wetsuit looks gray.  That is why photography in those
> depths
> requires artificial lighting.  The white light of an electric lamp
> includes
> red wavelengths, which can be selectively reflected by objects having
> the
> inate ability to do so.  However, in the absence of white light or
> some other
> source of red radiation, such objects are not in fact red - they can
> only be
> said to be potentially red.  They possess the ability to appear red if
> and
> when red light becomes available.
>
> Paul M.
>