Today we start the second chapter of Tractate Chullin. We’ve spent the past month learning primarily about who can slaughter a kosher animal, and now we turn to focusing on what that slaughter actually entails. The “how” of kosher slaughter is centered on the idea of what the rabbis call simanim (singular siman), signs. The simanim are two major organs in the neck: the trachea and the esophagus. These organs must be cleanly severed in the shechita of mammals. But the requirements are different for other animals.
The mishnah states:
One who slaughters by cutting one (siman) in a bird, and two (simanim) in an animal, his slaughter is valid. And the majority of one is like the whole.
The Talmud starts with a very basic question: Why does the slaughterer have to sever both vital organs in a mammal, but only one in a bird?
Bar Kappara teaches: “This is the law of the animal, and of the bird, and of every living creature that moves in the waters, and of every creature that swarms upon the earth” (Leviticus 11:46). The verse situated the bird between the animal and the fish. To require two simanim is impossible, as it was already juxtaposed to fish. To exempt it with nothing is impossible, as it was already juxtaposed to the animal. How is it made kosher? With one siman.
Leviticus 11 lays out which creatures are kosher, concluding with a summarizing list: mammals first, followed by birds, then fish and finally crawling, swarming critters. Bar Kappara reads this list as hierarchical. At the top, mammals require both to be severed. At the bottom, fish and swarming creatures require no ritual severing of organs. Birds land in the middle. Bar Kappara concludes, therefore, that kosher slaughter of birds requires only one siman to be severed.
After discussing Bar Kappara’s explanation, the Talmud offers another possible source for this ruling:
A passerby from the Galilee taught: Kashrut of animals, which were created from the land, is accomplished through cutting two simanim. Kashrut of fish, which were created from the water, is accomplished with nothing. Kashrut of birds, which were created from mud — through one siman.
Where Bar Kappara proved his point through a biblical verse, the unnamed Galilean makes the argument by combining (implied) biblical verses and his own observations of the natural world. In Genesis 1:20, God commands that “the waters bring forth swarms of living creatures, and birds that fly above the earth across the expanse of the sky.”
In Genesis 1:25, God commands that “the earth bring forth every kind of living creature: cattle, creeping things and wild beasts of every kind.” Fish clearly come from the water, where they continue to live, and mammals come from the earth, where (for the most part) they are still found today.
Birds are a special case. According to Genesis 1:20, it sounds like birds are created from the water. But Genesis 2:19 tells us they were formed from the earth. So are birds created from water or land? According to Bar Kappara, both! Anyone who gardens can tell you that water plus earth equals mud, hence his claim they were made from that oozy substance. It follows that the kosher slaughter of birds combines elements of the slaughter of fish and the slaughter of mammals, meaning only one siman.
Rav Shmuel of Cappadocia says: Know that birds have scales on their feet like fish.
Rav Samuel of Cappadocia (what is today Turkey) supports the unnamed Galilean’s position with his own visual observation: Birds share some characteristics with mammals, presumably he is comparing soft feathers with downy fur — and others with fish, which are covered with scales, reminiscent of birds’ tough feet. The Talmud doesn’t try to determine which of these explanations for the halakhah of bird slaughter is correct. Instead, it leaves both explanations side-by-side, presenting a worldview in which the words of the Torah and empirical evidence can co-exist and support each other — at least in this case.
Read all of Chullin 27 on Sefaria.
This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on May 27, 2026. If you are interested in receiving the newsletter, sign up here.
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