Five  Senses of smell Taste Touch Vision Hearing Sense of smell Contrary to the sharks which have an extremely developed sense of smell, the dolphins appear to have lost their faculties of detection of the odors. Indeed, the olfactive nerve and the olfactive bulbs of the brain disappeared and it is the same for the chimio-receiving cells of the nasal mucous membranes of the vent.

The sense of smell, very developed at the predatory terrestrial ones, loses of its importance in marine environment because water has the capacity to dissolve the odorous molecules, making their propagation certainly very diffuse. The dolphins developed another system of detection much more powerful to seek their preys, echolocation. Taste The language of the dolphins has papillae and small cavities rich in cells chimio-receiving which confers certainly on these animals very developed gustatory feelings. It takes part not only in information on the ambient conditions, but it can also play a part in the social behavior. The gustatory sensitivity of the dolphins would enable them to recognize the sexual phéromones announcing the availability with the coupling, or substances intended to mark out corridors of migration. Touch The direction of the touch is important at the dolphins. Their skin comprises a network extremely complex of nervous terminations of which the sensitivity is increased by the fact that the skin is deprived of the cells corneas which, in the other animals, decrease the smoothness of tactile perceptions. Thanks to this sensitivity, the dolphins can induce, undulatory microdistortions to improve theirs swimming performances. When they are let touch, they appear very sensitive to the caresses, with privileged areas (on the head, around the vent, for example). One saw orcs pâmer of pleasure when the language was cherished to them. Somes points of the lower head and the jaw are even sensitive to the pressure; the dolphins would make use of it to evaluate their speed. Vision The experiments carried out on the dolphins as their exhibitions in the marinelands showed that they have a completely remarkable visual capacity. Indeed, it is always astonishing to note the precision with which a large captive dolphin aims a ring placed at five meters above surface, then leaps out of water and seizes it without problem with the nozzle. And is not it extraordinary also to observe one flotilla dolphin to spout out, pass through cerceaux in parallel without the touch, and to fall down all at the same time without running up? And which vision the orc, this monster of 2.000 kg, must it have when it rises out of the water of several meters to seize delicately, except for the centimetre, the exceeding fish of the mouth of the adjuster? Which are thus the adaptations developed by the dolphins to carry out such performances? If their eyes are examined, one notes that the crystalline lens is quasi spherical, a little like that of fish, and that the ocular sphere is flattened in the direction anteroposteror, which gets a vision adapted to the marine environment to them. One also noticed that the surface of the cornea is irregular, probably allowing a better accommodation at the time of the drainage duct the air, which is confirmed by the presence of powerful muscles ocular, ready to change the shape of the crystalline lens and the curve of the cornea according to the medium in which the dolphin evolves/moves. From the position of their eyes, the dolphins have a mainly monocular vision, which explains that they are obliged to move their body to look at eye successively, then other, an object located at the bottom. Eyelids deprived of lashes close the eyes of the dolphins when they sleep. Glands secrete a thick and oily liquid which permanently covers surface with the eye to protect it from salt and other corrosive agents of sea water. The dolphins have lachrymal glands, one will not thus see them never crying even if they have sorrow. Hearing To increase the hydrodynamism, nature eliminated the auditive houses. The external body is thus tiny room to a very small opening with flower of skin. It seems that the sounds are perceived by the small bones of the mandible, then transmitted to the inner ear, made up well, including/understanding ossicles (hammer, anvil, clamp), by the fat cushion which surrounds the tympanic bone. When the man is in water, the sounds reach him of all shares without them being able to identify the source of it. But the Cetacea would not be satisfied with such an approximation and their auditive apparatus manages to fill this gap. The bone of the tympanum is isolated from the remainder of the brain-pan by a layer of grease, and inside, the significant part of the ear is isolated by a bulb containing from the air. Variations of density of all these structures indicate to the animal from which the sound comes. The number of cell which innervent the ear - two or three times higher than at the man and the important size auditive nerve indicate that the Cetacea manage very well to discriminate the tone and the sound waves at high frequency. Hearing is particularly important, as the strong development of the auditive zone of the brain proves it. The dolphin uses it for its system “sonar”, or system of “echolocation”, which enables him to locate very distant objects and to move the night without anything to run up. When this system has suddenly been disturbed or faded because of parasites or electromagnetic interferences, it can happen that the dolphins are failed.