text: how is the kidney of a desert rat, a beaver or a dolphin different to that of a humans? biology work, any ideas? this is to do with the length of the loops of henle in the medulla of mammalian kidneys. the loops work as countercurrent multipliers providing a relatively high concentration of solutes deep in the medulla. long loops generate a very high solute concentration relative to general body tissues and this promotes the reabsorption of water from the glomerular filtrate. a desert rat has very long loops of henle. i'll let you work out the rest!