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 ...

JOINT BASE LEWIS-MCCHORD, Wash. -- The four Soldiers who stood over the shark tank knew what creatures lurked below. But as large flashes of gray streaked across the dark water, they willingly ...