The brain and central nervous system of the Bottle-Nosed Dolphin is much like that of a human. They are claimed to be almost as intelligent as humans (the common way to determine the intelligence of a species is by the convulutedness of its brain (Gyri and Suculi). The dolphins swim synchronized to show that they are speaking on a certain wave length. They also have two stomachs and can't smell very well (Dolphin Talk). Among other things, their two greatest commonalities and differences are within their hearing and sight.
- The Dolphin has a larger, more complex, auditory cortex than a human does. They also have roughly 4 ear canals, 2 external ears, and what is believed to be hearing through their jaw's like many other whales.
- Evolution from land to aquatic environment has left the dolphin with the same hearing as humans, plus some, to survive under water. Such benefits of a larger auditory cortex, and many canals, is for the purpose of echolocation. Echolocation allows them to pinpoint precisely where noises come from both above and below water, also between a larger range of Hz than humans can hear. Humans hear roughly .02kHz to 20kHz as dolphins can hear and understand 40kHz to 160kHz (Ridgway).
- The visual system of the dolphin is a lot like the human in the sense that they have both rods and cones, report back contralaterally, and have well developed optic nerves, but differ in the sense that the dolphin has evolved over time to be able to see and decipher better than most mammals in the both bright and dim light, and also above and below water. They have a more developed tapetum lucidum, which refracts light back through the cornea a second time to enhance vision in dim lit areas. They also lack the S-cone which removes the color blue from their color spectrum, allowing them to make out predator and prey in the ocean (Bottlenose).