The Great White Shark (Carcharodon carcharias) is the ocean’s apex predator. This powerful hunter is known for its immense size and varied diet across the global ocean. Great White Sharks do consume other sharks and rays. This behavior is a recognized part of their complex feeding ecology, demonstrating their dominance within marine food webs.
Confirming the Diet: Evidence of Shark Consumption
Scientists employ multiple methods to confirm that sharks and rays are a regular part of the Great White Shark’s diet. The most direct evidence comes from analyzing stomach contents, which reveals the remains of smaller elasmobranchs, the group that includes sharks and rays. These analyses show that juvenile Great Whites often prey on smaller species like bottom-dwelling stingrays and small sharks.
Advanced techniques like stable isotope analysis provide a long-term view of the shark’s diet by examining chemical signatures in muscle tissue. This method has indicated that other sharks can make up a large proportion of the Great White diet, even near seal colonies. Tracking studies also provide direct, real-time evidence of this predation. Researchers attach specialized tags to smaller species, such as smooth-hound sharks, that signal when the animal has been consumed by a larger predator.
Apex Predators and Intraguild Predation
The act of one shark species preying on another is known as intraguild predation. This occurs when a predator kills and consumes a competitor that shares the same resources, combining competitive and predatory behavior. For Great White Sharks, smaller elasmobranchs, including smooth-hound sharks and species of dogfish, are frequent targets.
This feeding behavior is often opportunistic, meaning Great Whites take advantage of available prey when it is easy to catch. In some regions, Great Whites have been observed gathering near river mouths where smaller sharks congregate to breed. The decision to engage in intraguild predation is driven by localized prey availability or high energy demands. One study reported that 70% of tagged smooth-hound sharks were consumed by Great Whites in a specific area.
The Broader Great White Diet
While they eat other sharks, the primary diet of an adult Great White Shark is rich in high-calorie prey, which fuels their massive bodies and migratory movements. As Great Whites grow larger, their diet shifts from smaller fish and rays to energy-dense marine mammals, such as seals, sea lions, and dolphins. This shift to fattier prey is necessary to meet the high energy requirements of a fully grown shark.
Marine mammals offer the caloric density required to sustain a large predator during long periods of travel and hunting. Their diet is supplemented by large bony fish, or teleosts, including tuna and salmon. Great Whites are also opportunistic scavengers, readily feeding on the carcasses of dead whales. This varied menu ensures the shark meets its nutritional needs, prioritizing energy efficiency and local abundance.