6. Feb, 2016

Sniffing your way back home: olfaction contributes to pelagic navigation in sharks

How sharks navigate in the great oceans has always been a mystery. Terrestrial navigators  use cues like earth rotation and  the position of  the sun to navigate. Cues that are difficult  to perceive by sharks swimming  a greater  depths in the oceanic currents. Many type of  pelagic sharks, like tiger sharks, great whites and hammerheads have extraordinary navigational abilities and can find their  way in the big oceans to destinations  often hundreds of miles away. Their migratory paths to their selected locations also  seem  to follow almost straight  lines 

Investigator Andre Nosal  from  the  Scripps Institution of Oceanography of La Jolla recently discovered (see Plos one) that leopard sharks Triakis semifasciata follow their nose. 'Leopard sharks were captured alongshore, transported 9 km offshore, released, and acoustically tracked for approximately 4 h each until the transmitter released. Eleven sharks were rendered anosmic (nares occluded with cotton wool soaked in petroleum jelly); fifteen were sham controls.'  The controls appeared to follow almost straight paths back to the shore. In contrast, anosmic sharks  followed more tortuous  and random-like  paths. So it seems  that  these sharks rely on their olfactory bulbs  in tracking a dynamic chemical environment and linking locations in olfactory space. Further reading:

Nosal AP, Chao Y, Farrara JD, Chai F, Hastings PA (2016) Olfaction Contributes to Pelagic Navigation in a Coastal Shark. PLoS ONE 11(1)