If the membrane is absent, as for white sharks, the eye is rolled upwards for protection just before the shark bites. Hearing Sharks have been attracted to low, irregular pulsing from distances of over a mile. The vibration resembles the sounds made by erratic swimming or convulsing fish. These sense vibration, change in pressure, movement and sound. Olfaction Nostrils used for olfaction only, not for respiration as in humans and terrestrial animals.
Sharks can sense blood in the water as little as one part per million from a mile away.
Ampullae of Lorenzini Receptor cells located at base of canals on sharks' snout, lower jaw and around the eyes. Combined with the lateral line system form the Bioelectrical Sensory System. Detects electrical field, its direction and intensity. All living creatures give off an electrical field. This sense can be uses to detect changes in sharks own bioelectrical field.