The Blue World: A shark's sixth sense
By CGTN's Gao Yuxin

Sharks have the same senses as humans: smell, touch, sight, taste and hearing. They also have a sixth sense called Electroreception, making them powerful hunters in the ocean.

As highly sophisticated sensory organs, the ampullae of Lorenzini are concentrated on the head, particularly on the ventral and dorsal surfaces of the snout and posterior to the eye are called electroreceptors, allowing sharks to sense electric fields in water. 

Each ampulla consists of a jelly-filled canal opening to the surface by a pore in the skin and ends in a cluster of small pockets full of a jelly-like substance. The ampllae are concentrated on the head, particularly on the ventral and dorsal surfaces of the snout and posterior to the eye. 

Every animal living in the ocean creates electric signals and the ampullae of Lorenzini enable sharks to detect weak, low-frequency electrical fields given off by prey.

Even in murky waters or the dark, they can accurately sense the prey's position and hunt it.

Sharks are usually about 7 centimeters to 10 meters long. Based on fossilized teeth and scales, scientists believe that sharks have been around for more than 400 million years – long before the dinosaurs.

This fierce killer of the sea can also be vulnerable when facing humans.

Sharks are threatened by the demand for their fins, overfishing, fisheries by-catch, habitat and prey loss, and human disturbance.

Overfishing is the biggest threat to shark survival. Sometimes fishermen cut the fins off live sharks and dump the animals – finless – back into the ocean, where they'll drown or bleed out. According to National Geographic, an estimated 100 million sharks are killed each year, mostly to supply demand for shark products.

About The Blue World series:

The ocean covers more than 70 percent of the Earth. In this blue world, there are all kinds of marine life with surprising abilities we don't know about. In this series, CGTN guides you through the journey of exploring the amazing animals in the ocean. 

For more:

The Blue World: The mystery of the sex of green turtles

The Blue World: Brainless jellyfish

The Blue World: Half asleep, half awake dolphins

The Blue World: Never make a pufferfish angry

The Blue World: From round fish to flatfish

The Blue World: When a whale sinks into the sea

The Blue World: Sea otter's treasure chest

The Blue World: Mother octopuses' mission

The Blue World: When the beauty of coral fades

The Blue World: Whale beachings

(All images via VCG)

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