A study published on Wednesday in PLOS ONE, revealed that sharks use their noses to navigate better. Until now, a big mystery involved the straight navigation of the sharks on long distances. Apparently, sharks use their noses in order to point the direction.
With the help of their nose, they use their smell sense that is very well developed, mostly because of it is used while hunting. The researchers said that sharks have the ability to smell the chemical changes that occur in the ocean, as they swim. The study is the first one that has proved that sharks have the ability to smell, even though it has been hypothesized in the past. Hypothesis of the kind were developed around turtles and birds as well.
Andrew Nosal, an oceanography researcher said that scientist have known for a long time that sharks were able to travel for very long distances. But the question on every oceanographer was how was it possible for them to travel such long distances, and keep a straight path.
For the research, 26 leopard sharks were captured from the La Jolla area in California. After that, the team of researchers took them approximately 6 miles away. Half of the sharks were put cotton balls that had been previously dipped in petroleum jelly in their nares. This helped impair their smell sense temporarily. After that, the researchers attached acoustic trackers to the leopard sharks and then they released them in the ocean.
In order to make sure that the sharks didn’t find their way home by picking up some clues on the way, their sight was blocked by covering the tank in which they were being held. The geomagnetic cues were blocked with the help of a magnet that was placed on the tank. The chemical cues were minimized by oxygenating the water from a scuba tank.
According to Nosal, the researchers wanted to confuse the sharks as much as possible. They even released the sharks in random and different directions. 62% of the sharks whose smell sense wasn’t impaired ended up close to where they were found, in a straight line. Only 37% of the sharks with impaired smell came close to the shore, and they didn’t do it in a very straight line. The fact that these sharks made it close to the shore suggests that they were helped by other cues. The acoustic cues that are used by turtles, could be the ones that helped the sharks get to the shore.
Nosal also said that this was only the beginning and that further studies will be done in order to see how exactly do sharks use their noses to navigate better.
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