Explorer of the sea © Nuno Sa/Minden Pictures
This blue shark is swimming near the Azores, a Portuguese chain of islands about 850 miles west of mainland Portugal. The inspiration for the shark"s name comes from its back color, which can vary from a light blue to a darker shade. Its slender, tapered body is propelled through the water with agility and grace by a long tail fin that sweeps from side to side. Listed as "near threatened," blue sharks are found off the coast of every continent except for Antarctica, making them the most widely distributed of all sharks. Swift and powerful swimmers, blue sharks migrate long distances. It"s common for them to swim 1,200 to 1,700 miles or even farther, following the clockwise currents of the Gulf Stream in search of food, mates, and "just right" water temperatures.