A sixth sense for electricity
Smell, sight, hearing, a lateral line for feeling movement, and hundreds of tiny jelly-filled pores that pick up the electric fields of living things.
Electroreception
Sharks have hundreds to thousands of electroreceptors called ampullae of Lorenzini, which detect the electric fields given off by living things. Wikipedia Electroreception helps sharks, particularly hammerheads, find prey. Wikipedia
Each ampulla is a gel-filled canal that opens to the surface through a pore in the skin. Wikipedia The organs are named after the Italian physician Stefano Lorenzini, who described them in detail in 1679, without knowing what they were for. Wikipedia
The hammerhead’s view
Hammerheads are named for their flattened, T-shaped heads, called cephalofoils, with an eye at each end. Wikipedia The eye position gives hammerheads 360° vision in the vertical plane: they can see above and below at all times. Wikipedia
Feeling the water
Like other fish, sharks have a lateral line, a row of sense organs that detect movement, vibration and pressure changes in the water. Wikipedia
Smell
Sharks have a keen sense of smell. Wikipedia
Sight
Behind the retina, many sharks have a reflective layer called the tapetum lucidum, which bounces light back and helps them see in dark water. Wikipedia
In one study of 17 shark species, 10 had no cone cells at all, which means good night vision but no colour vision. Wikipedia