No mention of the huge techailes event in Boro Park on Chol Hamoed?!

youdont say
“You simply miss the point. This issue is not innovation”

That is one issue. there are others.

“thinker123
“If you really are interested I already told you were to look. ”
thanks. I found it.

“You have another explanation?”
Sure take your pick
1) He has questions on the murex
2) He feels techeiles wont be found before moshiach as the medrashi say (Ive heard this quoted in his name)
3) He doesnt want to change mesora based on academic research.

Feel free to add your own.
He doesnt have time, is less logical than any of mine

” Regarding what you are quoting, [realy sorry but a know it already”
Then it was abit dishonest for you to leave it out

” I usually try not to waste time on all the brisker bubeh maises,”

Even if a bubeh maisah I still have R’ yoshe Ber on my side.

“By the way, I don’t know if I’ll be wasting more of my time debating someone who never went thru the topic.”

nu nu. At least youve learnt something. Glad I can help

Yekke — you still haven’t let me know what your personal question for me is.

ubiquitein:
“No. so it isnt every mitzvah. you go on to list some more excellent examples…Um, that may be kefira. Repaying a loan, giving a Get are absolutly mitzvos”.
As you have vlearly misunderstood (for the umpteenth time), it is ONLY a mitzvah when P (the circumstances) call for it. Only a foolish man would say that one has a mitzvah to repay a loan if he has not borrowed. But isn’t that kefirah? Isn’t it a chiyuv to repay a loan? The answer is simple and glatt, (no brisker torahs need here), it is not a mitzvah if P (in this case the borrowing) is not there, but if P has been done, the AND ONLY THEN is it a mitzvah. Same with gitten and other mitzvohs. So in short, it is not that a person is not mechuyiv if P is not fulfilled, rather ther is no M IF AND ONLY IF P is not fulfilled. [think about this for some time, it is not too difficult].

“I think it self understood that you have nothing to say on this topic ”
about the silly comment of: no race to do mitzvohs.

No. It is with everything we do. From the very names of the aleph beis”
You have obviously not understood why I capitalized HALACHA. Go back and reread my comment, you should be able to understand it, again it is not to difficult.

you do realize there are midrashim that say tat about techelies as well
First off we don not paskn like aggadah, even for a brisker it is imperitive to learn kalalei hapsak.

About the CI
Actually you are contardicting yourself, since in such a case we are not uprooting a halacha, there is no halacha not wear techeilis.

apushatayid: It’s not ‘too busy’ but rather this is not a simple halachic concept, it has a lot to do with the metzyas. Did you hear Rav Chaims shittah on the new chickens? No, but why not, is he to busy to be mevarer? the answer that he is for such a type of question which involves a lot of detective work, and learning a metziyos.
It is well known that Rav Chaim only writes a sefer on an ibbur yair since otherwise he has no time. The Techeilis is no different.

From Rabbi Kaganoff:

Can We Identify the Techeiles?

Parshas Shelach includes the mitzvah of wearing techeiles on our tzitzis. Rashi, in the beginning of Parshas Korach, mentions that the followers of Korach donned garments that were completely techeiles. Therefore, whether we are in a place that reads Shelach this week or one that reads Korach, it is appropriate to read about:

Can We Identify the Techeiles?

wool-1196345-640x640When we are commanded about wearing tzitzis, the Torah includes two mitzvohs. In addition to the mitzvah of wearing tzitzis threads on the corners of the garment, there is an additional mitzvah that some of the tzitzis threads should be dyed with a special dye called techeiles. (It is a dispute among the Rishonim how many threads are to be dyed techeiles. That topic we will leave for a different time.) This dye must be made from a species called chilazon (Tosefta Menachos 9:6).

Although the regular use of techeiles stopped over a thousand years ago, there have been a few attempts within the last 130 years to reintroduce the practice of wearing techeiles threads alongside the white threads. This article will present the differing opinions on this question and some of the issues that have been raised.

At the time of the Gemara, the nature of chilazon and its manufacture was still known and practiced (see Menachos 42b). However, some time after the period of the Gemara, the use of techeiles ended. By all indications, techeiles fell into disuse sometime after the period of Rav Achai Gaon, the author of the She’iltos, around 4520 (760). Although I have seen it claimed that by the time, techeiles was no longer worn in his era (The Royal Purple, page 112), Rav Achai mentions some of the halachos of wearing techeiles (see She’ilta 126). Although there is no indication that, in his day, he knew people who were still wearing techeiles, he also makes no mention of the practice no longer existing. The obvious reading is that he knows that some people may still be wearing it.

There is an allusion in the Ramban that, in his day, techeiles was still worn, although it is possible that he was referring to the color and not the source.

It is unclear why the Jewish people stopped using techeiles. Numerous theories have been suggested as to why wearing techeiles ended, but these are all theories with no evidence to support them. The wording used by the midrashim is: “now, we have only white tzitzis, since the techeiles was concealed” (Medrash Tanchuma, Shlach 15; Medrash Rabbah, Shlach 17:5). Some poskim understand that there are halachic or kabbalistic reasons why techeiles should not be worn until Moshiach comes (Shu”t Yeshuos Malko #1-3). According to this opinion, the Medrash means that the source of the techeiles was concealed, and it is to be revealed only at a future time when Hashem wants us to wear it again.

Other poskim disagree and contend that we should still attempt to fulfill the mitzvah of wearing techeiles on the tzitzis. They explain that the Medrash means that techeiles became unavailable. Rav Herzog, zt”l, who followed this approach, speculated that persecution by anti-Semitic governments ended the production of techeiles (The Royal Purple and the Biblical Blue, page 112). Still another possibility is that the knowledge how to produce the techeiles was lost, or that there was no longer availability or access to the chilazon, the source of the techeiles.

The Radziner Rebbe’s Research and Conclusion

In 5647 (1887), the Radziner Rebbe, Rav Gershon Henoch Leiner, zt”l, published a small sefer, Sefunei Temunei Chol, wherein he discusses the importance of fulfilling the mitzvah of wearing techeiles, even today. In his opinion, the Medrash quoted above means that techeiles became unavailable, not that we are not permitted to wear techeiles. The Radziner encouraged wearing something that may be techeiles, because one is possibly fulfilling a mitzvah min hatorah. Thus, he contended that if he could identify a species that may be the chilazon, and he could extract a dye from it, then one should wear tzitzis that are dyed this way.

The Radziner, himself, analyzed every place in the Gemara where the word chilazon is mentioned and defined what characteristics would help us identify it. Based on his analysis, he drew up a list of eleven requirements with which one could identify the chilazon. Among other requirements, these included that the chilazon would be located in the eastern Mediterranean Sea; that it must be able to live on land, at least for a brief period of time; that it produces a black ink and that it must have fins, bones, and sinews. The Radziner concluded that if one located a marine animal that meets all the requirements, one can assume that it is the chilazon.

Having completed his halachic research, the Radziner then began his scientific research to identify the chilazon. He traveled to Naples, Italy, to study marine animals that would meet all the requirements of techeiles. In Italy, he decided that the cuttlefish, which in many languages is called an inkfish, is indeed the chilazon from which one produces techeiles. The cuttlefish meets every one of the Radziner’s requirements for chilazon, including that it emits a dark dye, which is the reason why it is called an inkfish. The cuttlefish is not a true fish and is capable of living on land for brief periods of time.

The Radziner then published his second volume on the subject, Pesil Techeiles, in which he announced his discovery of the chilazon and all his proofs why the cuttlefish meets all the requirements of the chilazon. Subsequently, the Radziner published a third volume, Ein HaTecheiles, whose purpose was to respond to all the questions he had been asked regarding his identification of techeiles. The three volumes have been republished together under the title Sifrei Hatecheiles Radzin.

Reaction to the Radziner’s Proposal

Although the Radziner took much effort to present his case, most of the Gedolei Yisroel did not support his theory. The primary reason for his publishing Ein HaTecheiles was to refute those who had disagreed with him and to convince others of the validity of his approach. He attempted to get several great poskim to agree with him, particularly, Rav Yitzchok Elchonon Spector (the Rav of Kovno and the posek hador at the time), the Beis HaLevi (then the Rav of Brisk), Rav Yehoshua Kutno (author of Yeshuos Malko, the Rav of Kutno and considered one of the poskei hador, particularly among the chassidim), the Maharil Diskin (who had been Rav of Brisk and was living in official retirement in Yerushalayim), and Rav Shmuel Salant (the Rav of Yerushalayim). None of these Rabbonim accepted the Radziner’s proposal. Their reasons for rejecting his proposal are significant.

The Brisker Approach

Beis HaLevi wrote that he was convinced that because of mesorah, the inkfish cannot be the source of the techeiles. There are two versions as to why the Beis Halevi objected.

According to this namesake and great-grandson, Rav Yosef Dov Soloveichek of Yeshiva University and Chief Rabbi of Boston, the Beis Halevi held that when the Torah requires the usage of a specific type or species of item to fulfill a mitzvah, one cannot do so without a mesorah that this is the correct object being referred to. Attempting to identify the type or species on the basis of research, analysis or proofs will not help; nothing can be substituted for mesorah. Thus, no matter how compelling the evidence is that a specific species is the chilazon of techeiles, one will not fulfill the mitzvah of wearing threads dyed with this color without the substantiation of the mesorah (Shiurim Lezeicher Aba Mari, Volume I, page 228). When Eliyahu HaNavi returns as the precursor to the Moshiach, he will identify for us the mesorah he received from his rabbei’im and, thereby, we will be able to identify the proper techeiles.

However, the Radziner quotes that the Beis Halevi disagreed with him for a different reason. According to the Radziner, the Beis Halevi’s concern was that since the inkfish was a known species, why would klal Yisroel not have observed techeiles for over a thousand years, if it could have? This proves that inkfish is not the source of the techeiles (Sifrei Hatecheiles Radzin, page 191).

Other Counter Arguments

Rav Yehoshua Kutno and Rav Yitzchok Elchonon disagreed with the Radziner for a different reason. In their opinion, the Medrash quoted above should be understood literally, meaning that techeiles had been placed in genizah until Hashem again wants us to observe this mitzvah. Their assumption is that the species that provides techeiles is not currently available and will become so only when Hashem wants. Rav Yehoshua Kutno suggests several reasons why this happened, reasons that are beyond the scope of this article.

Others were opposed to wearing techeiles, because of sources in the writings of the Ari and other mekubalim that say that we are not to use techeiles until the rebuilding of the Beis HaMikdash, bimheira beyameinu. The Radziner did not agree with their interpretation of these sources.

An additional objection was raised against the Radziner’s position that one should wear questionable techeiles, since one may be fulfilling the mitzvah. This is based on the poskim who contend that one who places blue tzitzis that are dyed with a dye other than techeiles on a white garment does not fulfill the mitzvah. Therefore, it is preferable to wear white tzitzis, if one is uncertain (see Rama, Orach Chayim 9:5).

There were also objections to the Radziner’s conclusions on other grounds. Some objected to his choosing a non-kosher species as the source or the techeiles, since there are early poskim who contend that the techeiles must come from a kosher species. Others contend that the color of the Radziner’s techeiles was wrong, since Rashi states that techeiles is green.

On the other hand, there were some gedolim who considered the merits of the Radziner’s position. The Maharsham wore a talis with the Radziner’s techeiles, although apparently he did so only in private. However, in the final result, only the Radziner’s own chassidim and some Breslever chassidim wear the techeiles that the Radziner introduced.

Rav Herzog’s Research

More than twenty years after the Radziner’s passing, Rav Herzog (later to become the first Chief Rabbi of Israel) researched the source for the techeiles. This was done as Rav Herzog’s doctoral dissertation and is now published under the title, The Royal Purple and the Biblical Blue. In his analysis of the halachic issues involved, Rav Herzog accepted most of the Radziner’s opinions and interpretations. However, there are some aspects of the Radziner’s approach with which Rav Herzog took issue. Whereas the Radziner assumed that every place in the Gemara mentioning chilazon refers to the chilazon that was used in making techeiles, Rav Herzog assumes that the word chilazon means a sea snail, and not necessarily the snail used in making the techeiles. Thus, in Rav Herzog’s opinion, not all of the Radziner’s requirements in determining the species for the techeiles are accurate (The Royal Purple…, page 76). Therefore, Rav Herzog focused on determining, from among the numerous species of sea snails, which ones are the most likely candidates to be the chilazon that was specifically used for producing techeiles dye.

There is one major point of the Radziner’s conclusions with which Rav Herzog took issue. Rav Herzog took samples of the dye recommended by the Radziner as techeiles and had them chemically tested. Based on results that he received from laboratories, Rav Herzog concluded that the blue color that results from the Radziner’s techeiles is not caused by anything in the cuttlefish ink. The chemists he consulted contended that the color is an artificial dye named Prussian blue, which was created by the chemicals added as part of the processing. Since he could not discern anything in the cuttlefish that causes the blue coloring, Rav Herzog reaches the conclusion that the cuttlefish could not possibly be the source of the techeiles (The Royal Purple…, page 116). (There are answers to explain how the Radziner might have responded to this question that are beyond the scope of this article. I believe that there is a website that discusses this.)

Rav Herzog conducted much research on which sea snail is the most likely source for techeiles. However, in his conclusion, he rejects each of these species because they do not meet all the requirements listed by the Gemara and Rambam. Thus, after much scientific and halachic research in his dissertation, Rav Herzog did not have a source of techeiles to recommend. However, in Rav Yechiel Michel Tukachinski’s work, Ha’ir Hakodesh Vehamikdash (Volume V, page 55), written many years later, he cites Rav Herzog as having decided that one of the species is, indeed, the correct source of the techeiles, although a careful reading of Rav Herzog’s article there implies that he was still undecided.

A point to note, is that Rav Herzog’s basic assumption, that chilazon must be a sea snail is based on his extensive background in linguistics. However, this is not a halachic argument. Each of the reasons mentioned by the poskim who disagreed with the Radziner’s proposal applies to Rav Herzog’s suggestions. We should also note that, in his explanation of the Gemara in Shabbos, which discusses how the techeiles dye is extracted from the chilazon, Rav Herzog took issue with how Rashi explains the Gemara. (The question is whether the word potzei’a in the Gemara means to squeeze the fluid dye out of the chilazon or to smash it.) I will note that Rav Herzog’s approach is probably the more obvious way to understand that passage of Gemara, and yet Rashi clearly rejects it. Although Rashi presumably never saw techeiles removed from the chilazon, he obviously had a compelling reason for interpreting the Gemara as he does. Until the era of techiyas hameisim, we will never know whether Rashi had a compelling proof from Chazal, an oral tradition, or ruach hakodesh that told him why he should understand the Gemara this way.

Recently, some have attempted to answer the questions raised by Rav Herzog regarding which sea snail is the source of the techeiles. These researchers have suggested that one of the species of sea snail named Murex trunculus may, indeed, be the source for techeiles. Rav Herzog rejected this species as the source for techeiles for several reasons that these researchers feel that they have resolved. Several works have recently been published advocating the wearing of tzitzis dyed with Murex trunculus extract, as a fulfillment of the mitzvah of wearing techeiles. One of the reasons cited as strong evidence of Murex trunculus being the source of techeiles is that it is rare to find in the marine world anything that will naturally produce a blue dye, and that since this snail is found in the correct geographic location, this should indicate the likelihood of it being the source of the techeiles.

It should be noted that the method currently used to process the dye from the Murex trunculus cannot be the correct method of dyeing techeiles threads. This is for the following three reasons:

The current method of extracting dye from Murex trunculus involves removing a gland from the snail, which would involve the melacha of gozeiz, removing part of a living creature. (According to many poskim, one violates this also by removing part of a creature that has since died.) Clearly, this could not have been the method of removing the dye from chilazon in earlier days, as can be proved from the Gemara (Shabbos 75a), since although the Gemara mentions other prohibitions, it omits mention of this one.
Another objection is based on the fact that it can be demonstrated from the Gemara that the removing of the source of the dye from the chilazon kills it, although one would prefer that the chilazon remain alive for as long as possible. However, in the process used to remove the dye from murex, the snail can remain alive for several hours after the process has been completed.
A third problem with the current method of using Murex trunculus requires an introduction. At the time of the Gemara, there were unscrupulous individuals who sold threads dyed with a coloring called kla ilan. This coloring is not kosher as techeiles, and therefore, someone wearing it on his tzitzis would not fulfill the mitzvah of wearing techeiles. According to the Aruch, kla ilan is indigo, a vegetable dye that has a blue color. Thus, the Gemara was concerned about someone selling indigo-colored threads as techeiles threads to an unsuspecting buyer. The Gemara describes a test that can be used to check whether the threads are kla ilan or techeiles, by testing the threads for colorfastness, whereby kla ilan would fade, whereas techeiles would remain fast. However, if the dye produced from Murex trunculus is indigo, and the substitute is also indigo, how could a chemical test for colorfastness be used to determine what was the source of the indigo?
We can also note that, in addition to the source quoted above from Rashi, it is quite clear that the Rambam could not identify Murex trunculus as the source of the techeiles. The Rambam describes that the “blood” that is the source of the techeiles is black when removed from the chilazon. The gland extract removed from Murex trunculus is clear when it is removed and changes color afterwards.

Obviously, I am not the first one to note these difficulties with the process of extracting dye from Murex trunculus. However, the responses I have seen to answer these questions are tenuous. It should also be noted that the descriptions used by Chazal to identify the chilazon are not a very smooth fit to Murex trunculus.

In conclusion, I personally remain unconvinced that either the inkfish or Murex trunculus are the correct sources of techeiles. It is also seems clear to me that the list of prominent poskim who disagreed with the Radziner would all still feel that we do not have access to the true techeiles.

ubiquitin: three points, first I’m glad to see you have finally realised your error, as you have not answered anything. Second of all as I have stated above, rav Chaim does not even write seforim if not for an ibbur yair, kol shekein this.
As for the Midrash, there are no such medrashim (unless you mean the sifri, bit if so it is obvious that you have never seen it inside…).

Regarding saying Krias Shma, neither Nusach Sefard nor Nusach Ashkenaz is known to be more (or less) correct than the other nusach.

So, what exactly transpired at this huge techeiles event? A hands on demo ho wto trap a chilazon? how to extract its dye? how to tie techeiles? a shiur on the various shittos on how many of the strings must be techeiles? did someone get up and scream about the terrible zionists? did someone lead the crowd in a lets go yankees chant? a discussion if colin kapernick should be the next spokesperson for techeiles? Please enllighten us,

“The Techeilis is no different.”

Seriously? A mitzvas that hundreds of thousands of yidden would be able to perform daily the way the torah prescribes it is something the gadol hador has no time for? Nobody thinks it is important to ask? Rav chaim himself doesnt think it is important to research? Does he wear tzitzis? Did Rav sheinberg z’l, who was rather meticulous about tzitzis spend any time on it? Why not?

In reading through some of the prolific online literature on the issue (BTW this subject is a great argument as to the value of the internet for limudei kodesh), I learned that Rav Tendler,shlita, the son-in-law of Rav Moshe, Z’TL has actually researched the issue and was ultimately supportive of Radziner Techelet as the “real deal”. Of all those who opine on the subject, I would suggest he is among the few really having the technical expertise to make such a claim (although as is his practice, does not asset that it is a chiyuv that must be adopted by all yidden) .

Thefakemaven

“It is well known that Rav Chaim only writes a sefer on an ibbur yair since otherwise he has no time. The Techeilis is no different.”

Too bad there hasnt been an ibbur yahr since the techeiles was rediscovered I guess.

“first I’m glad to see you have finally realised your error, as you have not answered anything.”
What?

GHD — isn’t that the rabbi dr. that goes up on Har Habayis kneged the halachic consensus of gedolei yisroel zt’l and shlita? And the one who argues on his father in law on numerous issues, like organ donations.

you dontsay

Im sorry I dont follow

“I think that this just demonstrates that you are a moving target.”
There are severla problems with techeiles. I am focusing on one. Namely uprooting mesora.

you said “You simply miss the point. This issue is not innovation”
I dont understand what you mean by this. There are several issues the one I am most concerned with tis the innovation. Though there are others.

(I concede that the issues are linked, if we were 100% certain MAYBE we can uproot mesora, but this is an impossibility as ad biasgoel few maintain we are 10% certain (R’ Shachter told me 99%)

” In any case, this issue has nothing to do with manuscripts.”

I disagree. IT is about academic research to decide a halacha. You cna say the CI was wrong, you can say here he’d agree. but they are certainly related.

ubequitein: For the last time! we must do ALL the mitzvohs, but a mitzvah (M) which is dependent on something (P), as long as there is no P THERE IS NO M. not we are not mechuyav, rather there is no M AT ALL AS LONG AS THERE IS NO P!

As for mesorah, THINK for a second, of course there is a mesorah for DARKEI PSAK, but here, the issue about a psak. I.e. your issue is that we have no mesorah that this is the true techelis, the only place we need a mesorah about specific things are by birds. But of course for כללי הפסק we need a mesorah. In short HOW we pasken we need mesorah WHAT we pasken has no meshorah.

As for the Gedolim, the issue is not that it is a hard topic, rather it touches issues that pertain to zoology, biology, botany, chemistry, archaeology, dyes among others. Most gedolim do not have the expertise in these fields, nor the time to get acquainted with it, But the ones that did do wear it such as R’ Belsky ztz”l and lbcl”c , R’ Karp, R’ Nechemya Goldberg

The fakemaven
“we must do ALL the mitzvohs, but a mitzvah…”
Great so not ALL Mitzvos! I’m glad we settled that. that is what IVe been saying all along.

“As for mesorah, THINK for a second, …”

I thought about it. now your turn.
what percentage of certainty would it take for you to abandon tthe Esrog in pklace of say the apple. (Yes it isnt 100% identicla , but roll with it.)
If you were 90% convinced that Pri Eitz hadar was the apple? 99%? 100% convinced?

Fakeman, the mishna brura makes it clear that a tallia sheila is actually given to the wearer and he is koneh it. So, I don’t see your point.

Most shuls nowadays have their talleisim privately owned and ashaliach tzibur or people receiving an aliyah are not koneh it. That’s why you don’t see them making a brachah.

“and making use of scientific inquiry to buttress an halachic argument.”

You have that exactly backwards.

Wow, there is so much to unpack here, but I simply won’t spend the time on all of it, The arguments range from those mentioned by Rabbi Kaganoff to pure drivel. All of Rabbi Kaganoff’s arguments are not original (besides maybe one of them), and have been answered. Moreover, some of them are simply incorrect, such as his argument in the name of the Yeshuos Malko (please read it in the original and you will see that he says no such thing). Furthermore, some of his claims stem from a lack of knowledge of the metzious.

@ubiquitin
I said: “and making use of scientific inquiry to buttress an halachic argument.”
You argue: “You have that exactly backwards.”

OK I will play the game too. You have it exactly backwards.

@yekke2:

By the way, no one is expecting the world to wear techeles.

There are certainly talmidei chachomim who have done plenty of research who have come to the conclusion that it’s not techeiles.

If you are convinced that it is, fine, wear it, but have the humility to accept that there are those who are very much inside the subject, are much more knowledgeable in halachah than you are, and disagree with you.

Furthermore, to assume that R’ Chaim came to his conclusion out of naivete is degrading.

While you’re with R’ Chaim asking mechilah, why don’t you ask him why he rejects murex.

youdontsay:

The answer to the first part of your argument is simple — when people argue from a lack of knowledge they don’t deserve respect.

I was actually referring to the way you speak about Gedolim, not about the way you speak to the posters here. But while we’re on the subject – I’d hate to be the type of person who only treats people respectfully if they earned it. You shouldn’t be treating people as human beings because they ‘deserve respect’.

Furthermore, it is no raayah what is mentioned in Teshuvos V’Hanhagos, since the Brisker don’t consider him one of them.

I thought we don’t listen to the Briskers anyway?! This has nothing to do with Briskers. It is a halachic discussion about the parameters and application of the ספק דאורייתא לחומרא dictum. I was referring to your distracting post about R’ Chaim not being l’halachah – so I quoted you a Posek who brings this svara.

I don’t think there is any תועלת for me to respond to your posts, much as I’d love to point out a couple of fallacies and inconsistencies in your rants.

Be gebetched.

you dont say
You replied “You have that exactly backwards” when I pointed out then when you said “and making use of scientific inquiry to buttress an halachic argument.” you had it backwards
You also correctly pointed out:
“mesorah in halacha means a derech in p’sak — how to go about paskning”

Allow me to elaborate.
If yo uare looking for chilazon you woudl start with MEnachos 44a
חלזון זהו גופו דומה לים וברייתו דומה לדג ועולה אחד לשבעים שנה ובדמו צובעין תכלת לפיכך דמיו יקרים
Youd look for a fish wih the body comparable to the ocean that rises once in 70 years and whose blood is used to dye. you would never find the murex since it meets none of those criteria (though it is expensive 😉 )

now I grant if you find the murex through other means and are convinced it is techeiles the question that it isnt a fish isnt much of a question (perhaps all sea creatures are called “fish” not sure why the Gemara couldnt say sheretz hamayim, but ok not the biggest question) ditto for it not being the blood that is used.
However this isnt usually how halacha works.

For example take the argument over brain death those who accept it dont argue that it is death based on a scientific definition or modern research. The argument si that a patient who is brain dead is dead based on the Gemara in Yoma and/or mishna in Ohalaos. (This isnt the thread to debate brain death, I deliberately wrote the above in a (hopefully) non-controversial manner).
This just isnt the case with murex. the arguments are primarily scientific/academic in nature with the Gemaras treated as secondary (at best) and many Rishonim (like Rashi) ignored. This isnt how halachic pesak is generally determined