Inside a Sardine Tornado

A tornado of sardines swirls around diver and photographer Erwin Poliakoff in the Philippines. Sardines are small fish that gather in large schools, a behavior that defends them against predators. As they travel across oceans and up coastlines to feed on plankton, they serve as a nutrient-rich food source for many larger animals like seabirds, sea lions, whales and other species. Because they are foraged upon by so many animals, scientists have included them in a group of small schooling fishes called "forage fish."