Freshwater Fishes and Amphibians
Freshwater fishes conserve salt in their distal tubules and excrete large volumes of dilute urine
Kidney function in amphibians is similar to freshwater fishes
Amphibians conserve water on land by reabsorbing water from the urinary bladder
Marine Bony Fishes
Marine bony fishes are hypoosmotic compared with their environment
Their kidneys have small glomeruli and some lack glomeruli entirely
Filtration rates are low, and very little urine is excreted