Rav Yehuda discusses the physical dangers of consuming chiltit (asafoetida), particularly on an empty stomach, which Rav Yosef expands upon by listing other hazardous foods consumed on an empty stomach.

The Gemara notes that Rav initially permitted an animal whose legs had been severed because he verified that the convergence of sinews (tzumat hagidim) remained intact. Shmuel, however, cautioned him that the severing might have been caused by a venomous snakebite, rendering the animal forbidden due to mortal danger. Shmuel proposed a specific diagnostic test to detect the presence of venom; upon execution, the test confirmed Shmuel's suspicion that the injury was indeed the result of a snakebite.

The Mishna enumerates the physiological kosher signs for animals, birds, grasshoppers, and fish. A kosher mammal must possess fully split hooves and chew its cud. While explicit kosher signs for birds are absent from the Torah, the Sages established four indicators: a bird must not be predatory (dores), and it must possess an extra digit, a crop, and a gizzard with an easily peelable inner lining. Rabbi Elazar b'Rabbi Tzadok adds another sign, noting that a bird that evenly splits its digits when perched on a rope is definitively non-kosher. For fish, the required signs are fins and scales, though the Sages debate whether multiple scales are required or if a single scale suffices. Kosher grasshoppers must exhibit four specific traits: four legs, four wings, two extra jumping legs (kartzulayim), and wings that cover the majority of their body.

A braita asserts that any animal that chews its cud lacks upper front teeth. After addressing a series of difficulties regarding this rule, the Gemara clarifies that the absence of upper front teeth serves as a reliable indicator that an animal chews its cud and is kosher, with the sole exception of the camel (namely, a young camel). This anatomical indicator is practically valuable in cases where an animal's hooves have been severed, leaving no other means to determine its kosher status.

To differentiate between domesticated animals (behema) and wild animals (chaya) - a distinction crucial for determining the prohibition of forbidden fats (chelev), which applies exclusively to domesticated species - a braita states that a wild animal is identified by its horns and cloven hooves. The Sages debate whether the horn alone is a clear sign or if both criteria must be checked. To resolve the anomaly of the goat and an ox, which possess both traits yet are classified as domesticated, the Gemara explains that the horns of a wild animal must be either branched, or layered, grooved, and rounded.

The braita further notes that a single-horned animal, known as the keresh, is classified as a wild animal. This introduces a discussion regarding legendary creatures, specifically the keresh and the tigris. The Gemara recounts an incident where a Roman emperor requested that Rabbi Yehoshua ben Hananya show him the tigris. However, the creature's immense power caused widespread destruction from a distance, prompting the terrified emperor to beg Rabbi Yehoshua to return the beast to its place.