South America's seas are rich in life, including huge shoals of fish, whales, southern sealions, dusky dolphins and Magellanic penguins. Fish shoals can be huge, and so attract lots of predators. A shoal of anchovies is attacked from all sides by the hungry predators. Dolphins split the large shoal into smaller shoals and drive them to the surface. Seabirds can now dive into the water to grab them. Sealions join the feeding frenzy. Soon there is nothing left of the anchovies but fish scales drifting in the water.