Active shark species like the mako and great white shark tend to swim closer to the surface because of their need for speed.

Other shark characteristics include using their gills to extract oxygen from the water, rather than breathing air. Unusual ...

(soundbite of whale shark breathing) SOMMER: Whale sharks are the largest fish species on the planet, as long as a school bus. This whale shark was a juvenile, though still about 16 feet long, and ...