To find the kashrus status of an organism, we first need to correctly classify it as plant, animal, of, or fish, as each group has its own distinct requirements. E.g., animals need to chew cud and have cloven hooves, while fish need (fins and) scales.

What is the halachic definition of a of (עוֹף)?

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    Penguins! Yum .
    – Double AA
    Commented Dec 11, 2014 at 20:30
  • @DoubleAA That would be a dag, wouldn't it?
    – Adám
    Commented Dec 11, 2014 at 20:30
  • Maybe? It's highly unlikely penguins were on Moshe's list of not-kosher birds. ("Thou shalt not eat penguins." "Psst...this guy is going 'penguins', if you know what I mean...")
    – Double AA
    Commented Dec 11, 2014 at 20:32
  • 1
    Related: judaism.stackexchange.com/q/50304/5323
    – MTL
    Commented Dec 11, 2014 at 21:36
  • 2
    E.g. Was the moa a bird? It had no wings (not even vestigial one), and its feathers resembled fur more than plumage.
    – Adám
    Commented Dec 12, 2014 at 16:00

1 Answer 1


Note that many translations have both a bat and an ostrich listed as "birds". As an example, Rabbi Aryeh Kaplan in Living Torah and the English translator in Rav Hirsch (his grandson Isaac Levy) use Bas Haya'ana as ostrich and ataleif as bat. These translations state that both an ostrich and a bat are halachically considered "of". Thus it appears that a bird is a "winged animal" whether or not it flies. A penguin would seem to be similar to an Ostrich in that it is a flightless winged animal.

Actually, if one wants to analyze a flipper and a wing, one could say that a fish "flies" through the water or a bird "swims" through the air. In both cases, they are propelled through the external medium by something very similar.

  • Why did you delete? Seems reasonable.
    – msh210
    Commented Dec 12, 2014 at 19:23
  • @msh210 Because I had two downvotes and did not want to spend more time on it. I will leave it undeleted until Sunday and see what happens. Commented Dec 12, 2014 at 20:49
  • Do penguins have wings or flippers? Are whales birds too?
    – Double AA
    Commented Dec 14, 2014 at 0:10
  • @DoubleAA Penguins have the equivalent of wings and are not restricted to the water. Whales would have flippers but are completely restricted to the water so they are dagim. Commented Dec 14, 2014 at 0:46
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    I agree that the Torah doesn't (necessarily) classify like Linnaeus, but how DOES the Torah classify? You can't just make assumptions without a source, or a at least a hint. Yes, the Torah calls both bats and ostriches of, but since their "wings" are already anatomically radically different, that is not enough to rule fish fins and lizard ribs as not wings. despite their
    – Adám
    Commented Dec 22, 2014 at 14:52

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