How Are Frogs Similar to Humans on the Inside?

Frogs and humans share a similar body plan, which is reflected in their skeletons, and have organ systems which are broadly similar in shape, location, and purpose.

Both frogs and humans possess a skull, spine, central nervous system, and the bones of the limbs are given the same names for each species. In humans the radius and ulna are separate bones that form the forearm. In frogs the bones are fused. The bones supporting the shoulder, the clavicle and shoulder blades, have a similar shape in both species.

Frogs possess much the same visceral organs as humans. They have a stomach, a urinary bladder, large and small intestines, a heart, a liver and lungs. They also have specialized digestive organs such as a gallbladder, pancreas, and spleen. Frogs have reproductive organs, testes and ovaries, much the same as humans, but the way they reproduce is different. Humans bear live young, whereas frogs release eggs into the water, and their young develop externally to their mothers.

Frogs can be thought of as having a simplified anatomy compared to humans, though in certain ways they are highly specialized. For example, human anatomy lacks the frog's long lower leg bones, and a human tongue is, if anything, a simplified version of a frog's, which is adapted for firing at prey and is extensible.