Horse-Eye Jack

Photo: Kevin Bryant · CC BY-NC-SA

Horse-eye jacks form rotating, tornado-like schools of several hundred individuals that orbit the north-facing pinnacles at North Rock, a behaviour likely linked to cooperative prey-herding at the reef edge where currents concentrate baitfish. They are one of the dominant large predators of Bermuda's open reef system, making coordinated attacks on anchovy and silversides that spill out of reef crevices. The schools provide one of Bermuda's most dramatic underwater spectacles, the fish packed so densely at times that visibility through the column is reduced to metres.