Ocean World | The Blue Planet | BBC | Episode 1

The opening episode shows how ocean life is regulated around the globe by currents and the varying position of the sun. Near a Pacific seamount, there is a large concentration of marine animals because when the current makes contact with the submerged rock, it forces upwards plankton and other organisms. This in turn attracts other fish to the area that are higher up the food chain, like tuna, and those that are higher still, such as silky sharks. Off South Africa, a similar situation occurs every June when sardines migrate and are pursued by a caravan of various predators. The South Atlantic waters are the roughest, and storms also churn up nutrients to the surface.