The five senses describe everything about surroundings. With smell, taste, touch, sight, and hearing, humans and animals can understand the makeup of everything around them. But, for some animals, there’s a sixth sense, and it’s practically invisible. It’s not the force or whatever mystical power. It’s an uncanny ability to sense disturbances in electric currents. This is called electroreception.
There’s some natural voltage created by the difference in the concentration of ions within the body compared to all living organisms. It is something that plants and animals need to maintain homeostasis. Any muscular movement can create a small electrical current, which includes muscle movements. It’s actually what’s being picked up from a heartbeat to make this.
How do sharks use electricity?
There are two ways that animals use electroreception. They either use their electric currents to sense how those currents bounce back to interpret their surroundings. Or they pick up the electric currents already being produced by other animals to locate prey. Electroreception is most common in some amphibians and fish. It is because saltwater is a fantastic conductor of electricity, especially compared to air. But bees have also been found to use electric fields to assess pollen in flowers. And some mammals have the sixth sense, too, notably the platypus, echidna, and the Guiana dolphin. But sharks are truly some of the best at using electroreception because they’re so sensitive.
In addition to their strong muscles, aerodynamic shape, and specialized fins, this sixth sense helps sharks be talented hunters. Great white sharks are so sensitive.
- They can detect 1,000,000th of a volt in a milliliter of seawater, and maybe even less than that.
According to the University of Birmingham, it is like connecting a double battery. Theoretically, a shark swimming between those two points could tell when a battery is switched on or off, which is wild.
That’s a sensitivity better than most state-of-the-art equipment used by electrical engineers. So how do they do it? It’s all due to a specialized sensory organ in sharks and rays called the ampullae of Lorenzini, named after Italian physician Stephano Lorenzini who discovered it back in 1678.
In the sea underneath the shark’s head, there is an array of practically symmetrical dots. These are pores connecting jelly-filled tubes to bulb-like structures in the shark’s head called ampullae. These electric fields travel into the pores under its head through the tubes to the ampullae. These tiny hairs read the signals and use a network of nerves to send a message to the brain.
This gives the shark the exact dimensions and location of the fish, helping the shark catch and eat it. It’s fascinating because there’s so much electrical noise going on in the ocean all at once. Besides all the animal and plant life, the salinity, temperature, water movement, and acidity produce a voltage that a shark can pick up. So to be able to distinguish prey amid all the noise is beyond impressive. In practice, a shark will use all of its senses to hunt.
Sharks lead to long canals that cluster together. When an electric charge enters a pore, it travels through the highly conductive gel in the canal to the ampulla, where special cells detect the current and send a message along nerves to the brain. That’s how stingrays can spot prey hidden beneath them, even though their eyes are on top of their heads. But the ampullae aren’t just for hunting. Pores also let it know if someone’s trying to sneak up on it from behind on the ray’s back.
From far away, a shark would smell and hear its prey. Vision and taste would kick in upon closer range. But during the final phase of an attack, electroreception precisely locates the prey and tells the shark how to orient its jaws. Beyond hunting prey, scientists believe that sharks also use electroreception to sense potential predators and find mates. Research is also being done on how electric currents could repel sharks from fishing hooks. This could help protect sharks against dangerous fishing techniques that kill sharks as bycatch when fishers go after other fish. This research could also help find a way to repel sharks from swimmers and surfers.
Shark prey by using electricity
Sharks are the apex predator, and over 400 million years, they have developed and involved a set of incredible super senses. The shark’s electro-reception is, without a doubt, one of the coolest and most supernatural senses that they have. It is the ability of sharks actually to sense electrical currents in the water. And they can, in fact, sense electric currents as small as one nano volt of electricity. It is tiny, but every living animal gives off these very tiny electrical currents through muscle contractions and particular heart contractions.
In fact, sharks can sense their prey’s heartbeat in the water, and electrical currents are given off by some other inanimate objects as well. Actually, the blood gives off a small electrical current because it is so full of electrolytes. Shark gets start sensing these electrical currents.
So they will use their other senses, such as their hearing, sight, or smell, which are senses. Their electro reception will take over, and they will use that as their primary sense to identify where their prey is and catch it. Sharks also use this electroreception to detect the electrical currents of the earth’s magnetic field, which allows them to do long-distance migrations across oceans with very minimal landmarks.
Almost all sharks are grayish with a darker top and lighter underside. It is called countershading. Imagine sunlight falling on a shark with no countershading. The top would be illuminated more brightly than the underside. It would make the shark very easy to see, and its shape is obvious. However, when darkening the top of the shark, it matches the brightness of the underside when sunlight falls on it. It’s much harder to see, and its shape has been disguised.
That is countershading, and it’s what sharks do to help blend in while swimming in plain sight. Other sharks like the Wobbegong live entirely on the bottom and hunt by ambushing their prey. They have evolved complex coloration and camouflage to blend into the seafloor. In addition to countershading, it has spots on top. Biologists think these help the shark use sunlight’s dappling near the ocean surface to disguise their shape.
Over the years, sharks have gotten a bad reputation that they don’t deserve. Sharks are brilliant and beautiful animals. Each year there are only about 140 shark attacks on humans. Many of those are provoked by spearfishers or the humans interacting with sharks in their natural habitat. Compare that to the nearly 100 million sharks killed by humans each year.
Electroreception. Bullock, Theodore Holmes. New York: Springer. 2005. ISBN 978-0387231921. OCLC 77005918.
Heiligenberg, Walter (1977) Principles of Electrolocation and Jamming Avoidance in Electric Fish: A Neuroethological Approach Springer-Verlag. ISBN 9780387083674.
Lewicki, M. S.; Olshausen, B. A.; Surlykke, A.; Moss, C. F., “Scene analysis in the natural environment.” Frontiers in Psychology.