Why sharks are unique
Sharks are fascinating animals that have evolved various adaptations to survive in their aquatic environment. One of these adaptations is their ability to sense electric fields, which helps them locate prey and navigate. Sharks have specialized organs which are jelly-filled tubes that open on the surface of their skin. Inside each tube, there is a bulb called the ampulla, which contains sensory cells that can detect tiny changes in voltage across the skin. Sharks can sense electric fields as weak as one millionth of a volt in water. The ampullae are distributed over the shark's head, snout and lower jaw, where they are most sensitive to the electric fields produced by living organisms. Sharks use electroreception for two main purposes: hunting and orientation. When hunting, sharks can detect the bioelectric fields of their prey, such as fish, crustaceans and marine mammals. These fields are generated by the movement of ions across cell membranes and muscle contractions. Sharks can also sense the electric fields of wounded or dying animals, which may attract them to scavenge. Electroreception allows sharks to locate prey even in murky water or at night, when vision is limited. When orienting, sharks can use electroreception to sense the Earth's magnetic field, which varies in intensity and direction across different regions. Sharks can use this information to navigate long distances and return to their home areas. Some sharks may also use electroreception to communicate with each other by modulating their own electric fields. Shark electroreception is different from that of other animals, such as electric eels, electric rays and platypuses. These animals can not only sense electric fields, but also generate them for defense, offense or communication. They have specialized organs called electric organs, which consist of modified muscle or nerve cells that can produce electric pulses. Shark electroreception is a remarkable example of how physics and biology interact in nature. By understanding how sharks sense electric fields, we can learn more about their behavior, ecology and evolution. We can also apply this knowledge to develop new technologies for underwater exploration, detection and conservation.