[Lee Stewart]

At one time it was thought that sharks had to constantly swim getting water through their gills so they can extract the Oxygen or they would drown. Then it was noticed in the Bahamas, groups of Nurse Sharks gathered together sleeping (not moving) on the bottom. So now we know that as long as there is a current moving water over the shark's gills they don't have to swim. They also found Reef Sharks doing the same thing. That does not hold true in stangant water though.