Hi,

I just reviewed your discussion on daf Shabbat 75 and found it most interesting. A couple of critical points I would like to bring to your attention:

1) In discussing the Murex trunculus as a possible candidate for the
hilazon-shel-tekhelet you dismiss it's candidacy based on three points

(d) netting ,(e) trapping , (f) wriggling. However you then go on to
explain that in fact parameter (d) is met and parameter (e) does find
concrete support. Therefore in fact, your ONLY grounds for dismissal
of the Murex trunculus is point (f). Thus I think it only fair that
you write the discussion such that (d) and (e) are not listed as
points of invalidation. Furthermore I believe that point (f) can be
fit in to the description of the Murex trunculus in that when one
takes it out of the water it "wriggles" into it's shell.

2) The reason the Radzyner squid is untenable can be proven right from
this daf (without having to go into the actual dye production that
blue must be added). The Gemara here states explicitly that the dye
comes out CLEAR (Layztil Tzeviyei). This is a characteristic which
you did not include on your list yet matches precisely to the Murex
trunculus, whose dye stuff is clear until exposed to oxygen.
Furthermore the squid's dye does not change upon death. However this
is another characteristic mentioned in our Gemara which precisely
defines the dye formation phenomena of the Murex trunculus. To quote
you from Dr. B. Sterman:

"Inside the hypobranchial gland of the snail, only the precursors to the dye exist as a clear liquid. When the precursors are exposed to air and sunlight in the presence of the enzyme purpurase which also exists within the gland, they turn into the dye material. Purpurase quickly decomposes, so in order for this reaction to take place, the gland must be smashed soon after being taken from the live snail, (in accordance with the Talmudic passage that the tekhelet is taken from the hillazon while still alive)."

I am attaching a couple of relevant articles for your perusal.

Tizke L'Mitzvot, Mois Navon.

P.S. The vast majority of people who are not wearing Murex Tekhelet do not attempt to refute the Murex but rather hang on the kabbala that awaits the Mashiach ... Bimheirah Viyameinu.