The stomachs of fish are generally simple or absent. This organ will tend to be more complicated in herbivorous fish for the same reasons as are noted in the 1st reading. If the stomach is present, some gastric secretions are usually produced. The intestine is basically a simple tube and little if any electrolyte retrieval occurs.
Much electrolyte balance occurs through the gills.
Terrestrial types have a more enlarged hindgut compared to fish. This larger, more complex intestine is mostly associated with water and electrolyte conservation. Amphibians also possess a cloaca, which is a common reservoir for digesta and urine. Amphibians also have simple, but functional kidneys, but these are much less efficient compared to those of mammals. They have a more pronounced large intestine.