Fig. 20.8. Cloacal regions.
Large renal corpuscle means more water in raw filtrate Thick intermediate segments mean many cilia to drive filtrate through tubule, which means less water will be reabsorbed One extreme: marine teleosts and mammals - concentrated urine Other extreme: freshwater teleosts and sharks - copius dilute urine Fig. 20.10. Nephron structure in representative craniates.
Red - water or ions into body Green - urine or ions out of body Fig. 20.11. Osmoregulation by “fishes.”