Sardines form a “baitball” under the surface of the water after being tracked by a mega pod of dolphins on the annual sardine run, the biggest migration of marine wildlife on the planet, in Port Elizabeth, South Africa. Forming a spiral formation around the fish, the dolphins were able to compress the baitball by surrounding it anticlockwise, gradually reducing the circle more and more. (Photo by Rainer Schimpf/Barcroft Images)
