Even our quite common Oliva sayana here in the Southeast United States
produces a similar excretion when "aroused."  When excreted it is virtually
colorless but when exposed to sunlight it takes on the "classic purple"
colour
as noted for Murex brandaris.  Interestingly, the result on skin is a purple
colour which lasts for nearly a month despite any attempts to remove it.  In
my
experience, larger specimens are more likely to produce the secretion - and
only
when stressed.  Also, you will know when you have it by the burning
sensation
which accompanies it. Vigourous rubbing of the area with salt water/sand
will alleviate
the burning but will do nothing for the inevitable coloration which follows.
 
Bill Frank
1865 Debutante Dr.
Jacksonville, FL 32246-8645
Phone/FAX: (904) 724-5326
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-----Original Message-----
From: Jorge Bartolomeu <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Friday, May 15, 1998 7:12 PM
Subject: purple dye
 
 
>        Dear, all
>
>
>        Have been noticing that certain shells like Bolinus brandaris,
Hexaplex
>trunculus, Opalia crenata and even the pelagic Janthina balteata produce a
>purple dye pigment? or fluid?. My curiosity is whether this pigment? or
>fluid?, is an act of defence or is it secreted by the animal when in
>stress, since when I collect live animals, they normally never show traces
>of this pigment? or fluid? Immediately ?
>        Is this purple dye present in many other shells besides these ? Do
(or
>did) any other cultures use similar pigments like the ancient Romans did ?
>        Would really appreciate hearing your comments !!
>        My very best shelling regards to you all,
>
>        Carlos