It appears that sharks use their noses for both hunting and navigation which might solve the mystery of their impeccable migration capabilities.
- A number of 26 sharks were taken for the experiment
- Half of the animals were deprived of their sense of smell
- Those who were affected took longer to find their way home
Andrew Nosal, a postdoctoral researchers at the Scripps Institution of Oceanography and Birch Aquarium in California took an interest in the matter, and investigated. He and his team captured a number of 26 leopard sharks in order to conduct his experiment. The plan was to take them away from their usual areas within the ocean, and then assess how they returned home.
Previous theories suggested that sharks find their way home through odor cues or by sensing the Earth’s magnetic field. However, it seemed that neither has been confirmed or properly examined.
Nosal took the step forward in order to reveal the true answer. According to the researcher, their incredible ability of swimming in a straight path directly toward their destination made them excellent enigmas. He wanted investigate how they do it, or what sort of cues they follow home.
First off, he made sure to confuse the sharks. When captured, the marine animals were not given any visual cues of where they were being taken. Their tanks were covered with tarps, and a strong magnet was placed above it to neutralize the geomagnetic hints. That way, it eliminated one possibility, and allowed liberty to test another: scent.
Half of the sharks were given a nose plug with a cotton ball dipped in petroleum jelly. All of them were then freed back into the ocean, around 6 miles (10 km) away from their initial areas. According to Nosal, just 30 minutes after they were released, those without nose plugs made the proper U-turn and headed back toward their homes.
The rest however, took much longer and appeared to move much more slowly when deprived of their olfactory sense. The temporary restriction halted their sense of direction, and seemed to suppress their impressive tracking abilities. Thus, the conclusion was drawn that their noses are more than accurate trackers of prey that made them so famously feared.
Some, such as Kim Holland, a marine biologist from the University of Hawaii, claimed that the sharks with plugged noses had a more difficult time heading home because they were confused. Any animal likely would be with one of their senses suddenly ripped away.
However, Nosal countered and stood by his theory, stating that those sharks didn’t seem to have a problem hunting and feeding. It only temporarily affected their navigation ability, not their actual senses. Whether their followed the scent of something from their home or environmental cues, their nose was key.
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