Cattle, pigs, chickens, humans—our collective evolutionary sculpting has left little differences between land-dwelling Animalia musculature. The most pronounced differences occur in the fats of animals. Fat absorbs surrounding molecules and compounds rather indiscriminately, and as such are, for the most part, responsible for the differences in flavor between the meats that we consume. In fact, were one to leave an uncovered fish in the same refrigerator as an uncovered stick of butter, the butter would soon take on the aroma and taste of the fish. This is generally an unpleasant affair, and while some day we may receive thanks from celestially-bound dolphins for all the fish, butter will only smell up your toast. It is largely for this reason that we cover the food in our refrigerators (in fact, it is the absorption of unpleasant odors that makes butter rancid). Certainly covering ones food prevents some cross-contamination, but in general, food will remain equally preserved at refrigerator temperatures covered, or uncovered (though one might argue that the evaporation of water from certain uncovered items, would decrease their microfaunal habitability, and thus actually be preserved longer than their covered versions…but we digress). The point is that it is the temperature of the food that plays the role of preserver, far less so the relatively shoddy attempts that we may make with plastic wrap.
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