Kangaroo rats living in the western American deserts have very efficient kidneys; they excrete an exceedingly small volume of highly-concentrated urine in order not to lose much water from their bodies. If you compare a desert kangaroo rat kidney and a human kidney you would see that the rat kidney has a relatively longer medulla than does the human kidney. Additionally, the collecting ducts and proximal and distal tubules are also relatively longer in the rat. Hypothesize and explain how the rat kidney anatomy might be especially valuable to survival in an arid environment.