How sharks sniff out their prey
Washington: Sharks have a keen sense of smell and a remarkable ability to follow their noses through the ocean, right to their next meal. Now, scientists have discovered how the sharks manage to keep themselves on course.
Researchers found that sharks can detect small delays, no more than half a second long, in the time that odors reach one nostril versus the other.
When the animals experience such a lag, they will turn toward whichever side picked up the scent first.
"The narrow sub-second time window in which this bilateral detection causes the turn response corresponds well with the swimming speed and odour patch dispersal physics of our shark species," known as Mustelus canis or the smooth dogfish, said Jayne Gardiner of the University of South Florida.
All in all, it means that sharks pick up on a combination of directional cues, based on both odour and flow, to keep them oriented and ultimately find what they are looking for.
If a shark experiences no delay in scent detection or a delay that lasts too long-a full second or more-they are just as likely to make a left-hand turn as they are to make a right.
These results refute the popular notion that sharks and other animals follow scent trails based on differences in the concentration of odor molecules hitting one nostril versus the other.
It seems that theory doesn't hold water when one considers the physics of the problem.
The study has been reported online on June 10th in Current Biology, a Cell Press publication.