Thresher sharks are distinctive marine predators recognized by their exceptionally long, whip-like tails, which can measure up to half the length of their entire body. These sharks inhabit tropical and temperate oceans worldwide, ranging from coastal waters to the open sea. They are highly migratory, often traveling across vast ocean basins seasonally.
Main Components of Their Diet
Thresher sharks primarily consume schooling bony fish, which constitute approximately 97% of their diet. Their staple prey includes small pelagic species such as herring, mackerel, sardines, and anchovies. Other common fish include hake, bluefish, and lanternfish.
Beyond schooling fish, thresher sharks also feed on cephalopods like squid. Less commonly, larger individuals consume bigger fish, such as lancetfish, cod, and even juvenile tuna. Occasionally, they prey on pelagic invertebrates like red crab and, rarely, seabirds.
Their Signature Hunting Method
Thresher sharks employ a unique hunting strategy using their elongated caudal fin. They use this tail, which can be up to 3 meters long, to stun or incapacitate schools of fish. This “tail-slapping” action delivers a powerful blow to their prey.
The hunting sequence involves four distinct phases: preparation, strike, wind-down recovery, and prey collection. During the preparation phase, the shark accelerates towards a fish school and then brakes by adjusting its pectoral fins, causing its posterior body to rise. The strike phase involves flexing its body and raising its tail overhead, whipping it forward at speeds that can exceed 24 meters per second (over 50 mph). This rapid tail movement generates explosive shockwaves in the water, which are sufficient to stun or kill multiple fish within the school. Following the strike, the shark enters the wind-down recovery phase, returning to swimming posture before collecting the stunned or dead prey.
Factors Influencing Their Diet
The diet of thresher sharks is influenced by their habitat and migratory patterns. These sharks are found in both open ocean and coastal waters, from the surface down to depths of approximately 550 meters. Their highly migratory nature leads them to follow seasonal changes in water temperature and prey availability, often moving northward in summer and southward in winter in the Northern Hemisphere.
Thresher sharks exhibit opportunistic feeding behavior, especially when specific prey is scarce. For instance, during less productive, warmer El Niño periods, they become less selective in their prey choices. Their relatively small mouth and smooth-edged teeth are suited for grasping and consuming the smaller, stunned prey from tail-slapping, rather than tearing at larger, intact fish. While they pursue prey day and night, their large eyes suggest an adaptation for low-light conditions, suggesting nocturnal or crepuscular feeding activity.