Elasmobranchs have an electric sense that enables them to detect electric fields.  All marine fish and invertebrates produce bioelectric fields, and these elasmobranchs can detect the electric responses from tens of centimeters away in the dense sea water. 

Specific Examples:
     Blue Sharks
          Carey and Scharold (1990) have tracked migrating blue sharks off the coast of northeast United States and found that they stay in a straight path and migrate hundreds of miles over a course of many days (Paulin, 1994). 

     Hammerhead Sharks 
          Studies have shown that Hammerheads follow a specific rout off the coast of California when the travel long distances.  Their journey correlates with the pattern of "magnetic anomalies on the ocean floor" (Paulin, 1994). 

     Round Stingrays (Urolophus halleri)
          Both male and female stingrays can detect weak bioelectric fields produced by other stingrays buried under the sand.  The slight charges are detected by stimuli arising from ionic charges at the skin in contact with the water.  These charges are then passed along the spiracles, gill slits, and mouth.  Recent findings suggest that the electrosensory function is expanded to include detection and localization during mating activity in the wild (Tricas and New, 1998). 

     Catfish
          Sensitivity to electric stimuli was first discovered in catfish by Parker and van Heusen in 1917.  When blindfolded, catfish responded to the presence of a metallic rod a short distance away.  The researchers concluded that the response by the catfish was associated by "weak galvanic currents at the interface between the metal rod and the aquarium water" (Tenforde, 1980). 

Hypothesis:
     Avian navigation is widely researched in regards to the complexity of their flight patterns.  It seems almost impossible for a bird to fly a thousand mile round trip journey to the exact location each year (Teneforde, 1980).  Although no definite research has been found to support such a notion, researchers are investigating this amazing phenomenon.