Any sea creature that lacks gills and can only breathe oxygen from air through lungs, or has an exoskeleton instead of an endoskeleton, is by default not kosher. The definition of scales does not include the shells of prawns and shrimp, which are in fact the exoskeleton ("outer skeleton") of these animals, in the same manner as the shells of lobsters or crabs. Even if these shells were to be misidentified as scales, these creatures would still not be kosher as they lack fins. While not every fish that has fins will have scales, every true fish that has true fish scales by default also has fins. Birds The Torah names only a few birds that may not be eaten; those not in the list are presumed to be kosher. However, the precise identity of the unclean birds is a matter of contention in traditional Jewish texts. It is therefore common to eat only birds with a clear masorah (tradition) of being kosher in at least one Jewish community, such as domestic fowl. Leviticus 11 lists, among other things, the specifically non-kosher birds. The Hebrew names listed have been translated as follows: Cormorant Eagle Gull Hawk Heron Hoopoe Red and Black Kite Osprey Owl (Horned, Screech, Little, White, and Desert) Raven Stork Vulture and Black Vulture Bats are also mentioned (though biologically, these are mammals rather than birds). Insects The Torah allows eating certain kinds of "winged swarming things" (e.g. insects) while prohibiting others. However, due to uncertainty about the Hebrew insect names, rabbis today recommend that all insects be considered unclean. An exception is made for certain locusts (Schistocerca gregaria), which are traditionally considered kosher by some Yemenite Jewish communities. details which insects are not to be eaten, and due to the wording all insects are considered impure to avoid mistaken consumption. Bees' honey is considered kosher because the honey is not a product made of bees. Explicit list The following animals are considered to be impure according to and , based on Rashi's identification: Bat Camel Chameleon Coney (hyrax) Cormorant Cuckow (cuckoo) Eagle Ferret Frog Gier eagle Glede Great owl Hare Hawk Heron Kite Lapwing Little owl Lizard Mole Mouse Night hawk Osprey Ossifrage Owl Pelican Pig Raven Snail Stork Tortoise Vulture Weasel Reasons Some scholars have conjectured that the Jewish concept of "unclean animals" arose out of public health concerns by community leaders, since, in the conditions