Researchers temporarily cut off sharks' senses to discover that some of them can navigate to find prey even with being able to see or smell.
Working in the Mote Marine Laboratory in Sarasota, Fla., the team looked at three types of sharks: blacktip, bonnethead and nurse, Discovery News reported.
"The biggest motivation with this multisensory approach was to try to understand what they're really doing in a natural environment with sensory cues," said Jayne Gardiner, a postdoctoral fellow at Mote, who led the study, as quoted by Discovery News.
As detailed in the study published in PLOS ONE, the scientists used a flow channel constructed in the tank with just enough room to hold a shark as it swam to find prey. The sharks were kept in one end in a holding pen while the prey, which was pinfish for nurse and blacktip sharks and shrimp for bonnetheads, was prepared at the other end.
As they moved down the 7-foot channel to the prey, the sharks were filmed with high-speed cameras. To have a control round, the researchers let the sharks pursue the prey with all of their senses the first time.
In subsequent experiments, the sharks' noses were temporarily blocked with bits of cotton soaked in petroleum jelly, and then their eyes were covered in small pieces of black plastic.
Once sight and smell had each been tested, the researchers took away the sharks' ability to sense movement in the water through hair cells that have receptors. Giving the sharks an antibiotic destroyed the hair cells for a few weeks so the animals couldn't use their heads and bodies as extra senses.
The researchers found that the sharks could adapt to snag food even without one of their senses. When their noses were blocked with cotton, the blacktips and bonnetheads still found their prey; however, the nurse sharks were not successful, showing that they do need their sense of smell to find food in the wild.
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