Digestive System
Most frog larvae are herbivores, where as salamander larvae are carnivores. However, adult frogs and salamanders are predators and feed on small invertebrates. After an amphibians eats, the food flows from its mouth to its esophagus to its stomach. Digestion begins in the stomach of an amphibian. Food then moves to the small intestine, where enzymes from the pancreas start the digestion process. From the small intestine, nutrients from the food are absorbed into the bloodstream and delivered to body cells. Food moves from the small intestine to the large intestine before waste is eliminated. Digestive waste enters the cloaca before it exits the body.
Excretion
Amphibians filter waste from their blood to their kidneys, and excrete either ammonia or urea as a waste product. Amphibians that live in water excrete ammonia, while amphibians that live in terrestrial environments excrete urea. Unlike ammonia, urea is stored in the urinary bladder until it reaches the cloaca.