Off Venezuela, a 30 tonne whale shark is filmed gorging on a school of fish rather than its normal plankton diet - proving adaptation and change is the key to survival. This program reveals the impressive swimming prowess of ocean dwelling common dolphin as they rocket at more than 30 kilometres an hour. By night, the ocean again spills into dramatic life. The nocturnal upward migration of billions of plankton near Hawaii is eagerly awaited by giant manta rays gorging in the darkness. In Costa Rica, the night hides squadrons of squid, desperately dodging the sonar of hunting spotted dolphin.