We now begin the sixth chapter, which deals with blemishes and the question of what is considered a blemish. Almost all the Mishnayos in the chapter, except for the last one, deal with a permanent blemish - a lasting blemish that will not heal. The common denominator of all of them is that these are blemishes visible to an outside observer, and they will not heal but will remain forever. Therefore, we will go over the animal limb by limb, beginning in Mishnah 1 with the ear.
The Structure of the Ear:
We are speaking of the external ear of a cow, goat, or sheep, which has two parts relevant to the halachos before us:
Cartilage - the part that gives the ear its structure and stability. This is the hard part of the ear, but it is not a bone: it is hard, stable, and flexible all at once.
Skin - the skin surrounding the cartilage, similar to the human earlobe.
The guiding principle: skin grows back after being damaged, whereas cartilage does not grow back.
The Mishnah opens with a list of blemishes, which continues over several Mishnayos: an animal that has one of these blemishes has a permanent blemish, and from now on it is permitted to slaughter it outside the Temple courtyard, as it is profaned by the very existence of the blemish, whether it was born this way or it was caused later. Nevertheless, the determination of the blemish must be made prior to slaughter by an expert, or by three valid members of a congregation; without this, it is forbidden to derive benefit from the animal, at least on a rabbinic level.
The Blemishes of the Ear in Our Mishnah:
"Pegimah" - a piece is missing from the ear, as if a triangle was cut out of it, even a tiny amount - provided the deficiency is in the cartilage. But if the deficiency is only from the skin, such as the earlobe or the rest of the skin surrounding the cartilage, it will heal, and it is not a permanent blemish.
"Nisdekah" - a slit in the ear, like someone cut into it with scissors: even though no piece is missing from it and the cartilage is entirely in place, the very fact that the cartilage is slit is a permanent blemish.
"Nekev" - a hole, even a tiny hole the size of a vetch seed, which is about a third of a barleycorn, is considered a permanent blemish.
"Yeveshah" - a dry ear, and the Tannaim disagreed on its definition.
What is a dry ear?
Tanna Kamma: "Kol shetinakev ve'einah motziah tipas dam" - any ear, even in the skin, that if a hole is made in it, even a small hole, it does not produce a drop of blood. This means that blood flow to the ear has ceased and it is dry, and no longer functions. This is a permanent blemish, and it is permitted to slaughter the animal.
Rabbi Yosei ben Meshullam: "Yeveshah shetehei nifreches" - it must be so dry that it crumbles: when one pulls on it, it breaks and crumbles. This definition is very reminiscent of the invalidations of the Four Species taught in Tractate Sukkah.
The halachah follows the Tanna Kamma: if the blood flow has ceased, and when one wounds or punctures the ear it does not produce blood - this is sufficient to call it dry. This is a permanent blemish, and it is permitted to slaughter a bechor with this blemish outside the Temple courtyard.