Short-beaked common dolphins (Delphinus delphis) hunting blue jack mackerel (Trachurus picturatus). The mackerel have formed a bait ball, a defensive manoeuvre performed by schooling fish that makes it harder for the predators to pick out individuals. However, it can also draw the attention of other predators, some of which have learnt how to take advantage of the tactic. This bait ball has been much reduced in size by the hunting. Photographed in the Azores.