A Great White's sensory system is so finely tuned that it is able to detect almost every signal or disturbance that occurs around it including smells, vibrations, signals, sounds and very low intensity electrical impulses.
SMELL AND TASTE
Although the senses of smell and taste revolve around chemoreception, there are different stately systems involved in each case.
Smell takes place in the nasal cavities, with 18% of the brain mass dedicated to analyzing the information provided by the olfactory organs. In fact, the Great White has the largest olfactory bulbs of any elasmobranch, being this sense of great importance in the sensory world of sharks.
Smell allows them to detect at the second any substance around them, being able to follow the trace to its source, sometimes several kilometers away. It is not only used to find food, but also plays an important role in social aspects such as mating. Males are very likely to find females by detecting the trail of their pheromones.
The sense of taste is found in the mouth and throat. It is mainly used to help the shark decide whether what is in its mouth is edible or not. When it bites into potential prey, the taste buds are instantly activated, informing it of the taste and even giving it caloric value data. A bad tasting or low-calorie food (such as a human) is dismissed, while a tasty energetic prey (such as a sea lion) is consumed.
HEARING AND LATERAL LINE
Differently from humans who have inner, middle and outer ear, sharks have only inner ear, a small hole that protrudes above the skin near the eyes. Inside, they have a lining of hair cells that vibrate to the sound waves and travel to the brain to be interpreted.
Their inner ear is able to detect not only sound, but also acceleration and gravity. A white shark is attracted to low-frequency pulsed sounds and can detect them up to 250 meters away. It can hear from a frequency of 10 hz (infrasound) up to 800 hz.
Great whites, like other sharks, can sense and identify the source of vibrations with another sense called lateral line. These are a series of sensory pores running along their sides, from head to tail, through which they detect water currents, vibrations and pressure changes.
The movement of the water creates a series of weak pressure ripples that sharks are able to discover through the receptor hair cells that carry these stimuli to the brain. An injured or sick fish would swim more clumsily than a fish that swims normally and creates little turbulence.
This sense can also alert them to predators in the area or changes in environmental conditions.
SIGHT
Despite their highly developed sensory system, Great white sharks rely primarily on their sense of sight for hunting. Like humans, they possess two types of cells in the retina: rods, adapted to detect contrast and movement even in low light levels, and cones, specially designed to distinguish detail and color differences when light conditions are higher. The rod-to-cone ratio in the Great White's retina is 4:1 (similar to that of the human eye), giving it the best vision in the shark kingdom.
Shark eyes also have a remarkable feature, the "tapetum lucidum", similar to the eyes of cats and other nocturnal animals. Located just behind the retina, this miniature plate structure causes light rays entering the eye to strike the shark's retina thereby increasing the light available to photoreceptors and improving vision in low light conditions.
Most sharks have a protective membrane, called the nictitating membrane, to protect their eyes, similar to our eyelid. The Great White, however, lacks this membrane. Instead, it rolls its eyes back into their sockets so that they are protected when approaching unfamiliar objects or striking prey.
Contrary to the popular idea that the Great White has "death" black eyes, the iris is actually a deep blue color, clearly visible in sunlight when viewed from the front.
A SIXTH SENSE
The Great White, like all sharks, possesses "a sixth" sense that we humans lack: "electroreception." Multiple rows of tiny pores are scattered around its head, mainly on its snout.
These pores are known as "ampullae of Lorenzini". This allows sharks to detect the electrical currents created by muscle tissue activity in living creatures and locate prey even in the absence of vision or in dark conditions.
The Great White relies on this sense during the final stage of a catch, just as it hides its eyes the ampullae of Lorenzini come into action.
Electroreception is also used by some species of sharks to navigate and allows them to sense the earth's magnetic field in order to orient themselves in their migrations in the absence of other geographic cues.
These six senses, added to other physiological characteristics such as the great difference in color between its back (dark gray) and its belly (white) in order to camouflage itself perfectly when stalking its prey and the ability to maintain its body temperature above the ambient water temperature, called endothermia, make it a perfect hunting machine. But we must not forget that this "hunting" is oriented only to its target prey, which certainly, without any doubt, are NOT human beings...