Extra Shark Senses
In the last section, we saw that sharks have a wider hearing range than human beings, as well as a much better sense of smell. As it turns out, they also use one sense we don't have at all.
The ampullae of Lorenzini give the shark electrosense. The ampullae consist of small clusters of electrically sensitive receptor cells positioned under the skin in the shark's head. These cells are connected to pores on the skin's surface via small jelly-filled tubes. Scientists still don't yet understand everything about these ampullary organs, but they do know the sensors let sharks "see" the weak electrical fields generated by living organisms. The range of electrosense seems to be fairly limited -- a few feet in front of the shark's nose -- but this is enough to seek out fish and other prey hiding on the ocean floor.
Water flows through the lateral line systems. Vibrations in the water stimulate sensory cells in the main tube, alerting the shark to prey and predators.
Another unique sense organ is the shark's lateral line. The lateral line is basically a set of tubes just under the shark's skin. The two main tubes run on both sides of the body, from the shark's head all the way to its tail. Water flows into these main tubes through pores on the skin's surface. The insides of the main tubes are lined with hair-like protrusions, which are connected to sensory cells. When something comes near the shark, the water running through the lateral line moves back and forth. This stimulates the sensory cells, alerting the shark to any potential prey or predators in the area.
By themselves, none of a shark's sense organs would be adequate for effective hunting. But the combination of all these senses make the shark an incomparable predator. The success of sharks is due largely to these physiological advancements -- they are superbly built to find food. They are also quite good at catching food, of course, as we'll see in the next section.