Many of the laws apply to animal-based foods. For example, in order to be considered kosher, mammals must have split hooves and chew their cud. The pig is arguably the most well-known example of a non-kosher animal. Although it has split hooves, it does not chew its cud. For seafood to be kosher, the animal must have fins and scales. Certain types of seafood, such as shellfish, crustaceans, and eels, are therefore considered non-kosher. Concerning birds, a list of non-kosher species is given in the Torah. The exact translations of many of the species have not survived, and some non-kosher birds' identities are no longer certain. However, traditions exist about the "kashrut" status of a few birds. For example, both chickens and turkeys are permitted in most communities. Other types of animals, such as amphibians, reptiles, and most insects, are prohibited altogether.