"Lantan fish off the Pacific coast of Costa Rica. They are one of the most numerous fish anywhere. Normally, they only come to the surface at night to feed on plankton. But this immense shoal has risen during the day, almost suddenly in order to spawn. For the dolphins, this would be a bonanza. They have located the shoal using their echo-sounding calls. But they have to get to it quickly. They are not the only hunters here. Yellowfin tuna have also detected the shoal. And behind them, with their two-meter wingspans, mobula rays. Now, sailfish, one of the fastest fish in the sea, have joined the chase. The Lantan fish may return to the deep at any moment. But now, the dolphins have got here. They swim beneath the shoal, pinning it to the surface and forcing the Lantan fish to pack more closely together. And now, the sea begins to boil. The tuna charge into the shoal at over 40 miles an hour. The slower swimming rays arrive at last. With their immense mouths agape, they scoop up the Lantan fish by the hundred. The shoal has now been largely dispersed. And the sailfish pick off the survivors. In just 15 minutes, all that's left is a silvery confetti of scales."