Chullin 59a
חולין נ״ט א — ד"ה מַתְנִי׳ סִימָנֵי בְּהֵמָה וְחַיָּה נֶאֶמְרוּ מִן
Chullin 59a:6
The sugya analyzes the Torah's signs for permitted locusts and discusses the role of a received tradition in identifying which species may be eaten.
מַתְנִי׳ סִימָנֵי בְּהֵמָה וְחַיָּה נֶאֶמְרוּ מִן הַתּוֹרָה, וְסִימָנֵי הָעוֹף לֹא נֶאֶמְרוּ, אֲבָל אָמְרוּ חֲכָמִים: כׇּל עוֹף הַדּוֹרֵס – טָמֵא, כֹּל שֶׁיֵּשׁ לוֹ אֶצְבַּע יְתֵירָה וְזֶפֶק וְקוּרְקְבָנוֹ נִקְלָף – טָהוֹר. רַבִּי אֶלְעָזָר בְּרַבִּי צָדוֹק אוֹמֵר: כׇּל עוֹף הַחוֹלֵק אֶת רַגְלָיו – טָמֵא. וּבַחֲגָבִים, כֹּל שֶׁיֵּשׁ לוֹ אַרְבַּע רַגְלַיִם, וְאַרְבַּע כְּנָפַיִם, וְקַרְצוּלַּיִם, וּכְנָפָיו חוֹפִין אֶת רוּבּוֹ. רַבִּי יוֹסֵי אוֹמֵר: וּשְׁמוֹ חָגָב. וּבַדָּגִים, כֹּל שֶׁיֵּשׁ לוֹ סְנַפִּיר וְקַשְׁקֶשֶׁת. רַבִּי יְהוּדָה אוֹמֵר: שְׁנֵי קַשְׂקַשִּׂין וּסְנַפִּיר אֶחָד. וְאֵלּוּ הֵן קַשְׂקַשִּׂין – הַקְּבוּעִין בּוֹ, וּסְנַפִּירִים – הַפּוֹרֵחַ בָּהֶן.
MISHNA: The signs that indicate that a domesticated animal and an undomesticated animal are kosher were stated in the Torah, and the signs of a kosher bird were not explicitly stated. But the Sages stated certain signs in a bird: Any bird that claws its prey and eats it is non-kosher. Any bird that has an extra digit behind the leg slightly elevated above the other digits, and a crop, which is a sack alongside the gullet in which food is stored prior to digestion, and for which the yellowish membrane inside its gizzard can be peeled, is kosher. Rabbi Elazar, son of Rabbi Tzadok, says: Any bird that splits the digits of its feet when standing on a string, placing two digits on one side of the string and two on the other, is non-kosher. And with regard to grasshoppers, whose signs were also not stated in the Torah, the Sages stated: Any grasshopper that has four legs, and four wings, and two additional jumping legs, and whose wings cover most of its body, is kosher. Rabbi Yosei says: And this applies only if the name of its species is grasshopper. And with regard to fish, the signs are explicitly stated in the Torah: Any fish that has a fin and a scale is kosher; Rabbi Yehuda says: Two scales and one fin. And these are scales: Those that are fixed to its body; and fins are those with which the fish swims.

