Feeding frenzy. A diver jostles for position with hungry seabirds while observing the Great Sardine Run — a mass movement of billions of sardines (Sardinops sagax) along the east coast of South Africa. The journey is thought to be one of the world’s biggest animal migrations in terms of biomass — the fish gather in shoals that are several kilometeres long, and attract swarms of predators including dolphins, sharks, whales and gannets.