The Nervous System in Amphibians

Amphibians are the first big steps away from fish and towards a mammalian nervous system; not only did they literally take the first steps on land, because of that, they were also able to take some evolutionary steps.

Image of a northern leopard frog.

While the brain of an amphibian, such as the frog above, is roughly equivalent in shape and structure to that of the average fish, amphibians evolved some new sensory features. For example, they have a tympanum, or ear organ, visible on the outside of their head rather than completely internal. Also, they have more developed eyes with a nictitating membrane to shield them from dust particles and keep them moist while outside of the water. They kept a similar nostril structure to fish.

These more developed sensory organs made amphibians far more equipped to hunting on land. They were also somewhat more precise than those of the fish. While frogs don't have as many sensory organs as some fish, they each serve their own purpose.