“Every creature on land has a parallel in the sea except the rat.” Chulin 127b. The rat is the only creature that is not worthy enough for Hashem to have a created a similar animal in the oceans. The Toras Kohanim in Parshas Shemini says “every creature that is Tamei on the land, its counterpart at sea is Tahor. That means that the rat is the only creature in the entire world is completely Tamei. It is further from Hashem than any creature on the planet.
Why is this? The Knaf Renanim explains that every creature has some redeeming feature from which people can learn from. The Gemara in Eruvin (100b) says that we learn Tznius from a cat, not stealing from an ant, etc. Each animal sings to Hashem thanking Him for its unique attribute. The rat doesn’t have a single unique attribute. It has nothing desirable in it character. What can we learn from the rat? We can learn that life no matter how worthless and how empty is a great gift in and of itself.
The rat sings, “Kol HaNeshama Tihalel Ka”, every neshama praises Hashem. Chazal tell us that the word Neshama in this pasuk can mean “Neshima”; breath. We thank Hashem for every breath he gives us on this earth. Whether life is good or bad; fulfilling or empty; whether we are capable of accomplishing great things or grounded by our handicaps; no matter what, we thank Hashem for life itself. Even is a person is unconscious and on a respirator he still thanks Hashem for every “breath” he takes. Each breath of life is a gift and its greatness should not be dismissed.