"In fact, the primary feature of clean animals is their feet, in one sense or another. To understand this, we must bear in mind that the ground was cursed under the Old Covenant (Genesis 3:17). Men normally wore shoes, and it was ceremonially important to wash the cursed soil off one's feet before entering a house...Holy ground, where the curse was removed, required men to go barefoot..."
--James Jordan, "Through New Eyes", Wipf and Stock, #101-102
Jordan then goes on to comment that chewing the cud (meditating on God's Word? Kind of reaching...) and wearing "shoes" (cloven hooves) are the distinctions of a clean land animal, that fish, to be clean, must also be shod: "in their case it means having scales. Scales are like armor that keeps th fish from contact with his environment..."--ibid, and that clean birds are picky about where they put their feet.