Orcas target the liver because it is, pound for pound, the most energy-rich organ in a shark’s body. A large shark’s liver can account for a quarter or more of its total body weight and is loaded with oils and fats that deliver an enormous caloric payoff for relatively little effort. When an orca rips open a great white shark and extracts only the liver, it is making a ruthlessly efficient foraging decision: grab the densest packet of calories available and move on.
What Makes a Shark Liver Worth the Trouble
Sharks lack the swim bladder that bony fish use for buoyancy. Instead, they rely heavily on their liver, which is packed with low-density oils, to stay neutrally buoyant. This evolutionary solution turns the liver into a massive oil reservoir. In many deep-sea shark species, squalene alone makes up anywhere from about 15 to 69 percent of the liver’s weight, with additional stores of other energy-rich lipids like triacylglycerols and diacylglyceryl ethers.1Australian Journal of Marine and Freshwater Research. Squalene content and neutral lipis composition of Livers from Deep-sea sharks caught in Tasmanian waters Great white sharks, though not deep-sea species, carry similarly oil-rich livers that can weigh hundreds of kilograms in a large adult.
Squalene is a hydrocarbon that packs tremendous energy per gram. To an orca, consuming a great white’s liver is like drinking several hundred kilograms of high-grade fish oil in one sitting. Compare that to eating the shark’s muscle tissue, which is lean, tough, and far less calorie-dense per kilogram. The cartilage skeleton adds no nutritional value at all. When food is available, orcas don’t need to eat every scrap of a kill the way a scavenger might. They can afford to be choosy, and the liver is the clear winner on a calories-per-effort basis.
How Orcas Extract a Liver with Surgical Precision
One of the most striking aspects of this behavior is how cleanly the liver is removed. Researchers examining shark carcasses that wash ashore after orca attacks have found remarkably neat wounds, often a single large tear between the pectoral fins that exposes the body cavity. The liver is gone. Other organs, including the stomach, intestines, and even the energy-rich heart, are left behind largely untouched.
Orcas accomplish this through a combination of strength and apparent anatomical knowledge of their prey. They seem to know exactly where to bite to access the liver cavity. In several documented cases off the coast of South Africa, the wound pattern was consistent across multiple shark carcasses killed by the same pair of orcas, suggesting a learned and repeatable technique rather than random tearing. The orcas appear to grip the shark, flip it to induce tonic immobility (a state of paralysis many sharks enter when turned upside down), and then bite into the ventral surface to access the liver directly.
This level of precision is not unique to orcas in the broader animal kingdom. Many predators practice selective foraging when prey is abundant, eating only the most nutritious parts and discarding the rest. What sets orcas apart is the scale and specificity: they are performing what amounts to a targeted organ extraction on one of the ocean’s largest predators.
The South African Great White Shark Phenomenon
The behavior captured worldwide attention because of events in South Africa’s False Bay and Gansbaai regions, two areas historically known for dense populations of great white sharks. Starting around 2017, great whites began disappearing from these waters. Carcasses washed ashore with their livers surgically removed. Researchers eventually identified a pair of orcas, widely known as Port and Starboard (named for the directions their collapsed dorsal fins lean), as the primary culprits.2African Journal of Marine Science. Further insights into killer whales Orcinus orca preying on white sharks Carcharodon carcharias in South Africa
What made the South African case so remarkable was not just the killing but the aftermath. Great white sharks, once common in these waters, essentially vanished from their usual haunts. The remaining sharks appeared to flee the area when orcas were present, sometimes for weeks or months at a time. This was not a subtle shift. Cage-diving tourism operations in Gansbaai, which depend on reliable great white sightings, saw their business upended. Seal Island in False Bay, once famous for dramatic great white breaching attacks on seals, went quiet.
In several of the documented kills, orcas removed not only the liver but also the heart, suggesting that while the liver is the primary target, other nutrient-dense organs are sometimes taken as well. But the muscle, skin, and cartilage are consistently abandoned. The carcasses that washed up were largely intact, missing only the visceral organs.
Do Orcas Do This Only with Sharks
Selective organ consumption in orcas is best documented with sharks, but the broader principle of picky eating extends across orca ecotypes. Different orca populations around the world specialize in different prey and show strong preferences for specific body parts. In the Pacific Northwest, resident orcas that feed on salmon often eat only the fattiest portions of a chinook salmon, particularly the belly and the head, and discard the rest when fish are plentiful. Transient (Bigg’s) orcas that hunt marine mammals sometimes eat only the blubber and tongue of large whale calves, ignoring the muscle entirely.
The pattern is consistent: orcas preferentially consume the tissues with the highest fat content. Blubber, liver, brain, and tongue are all disproportionately rich in lipids compared to muscle. For an animal that needs enormous daily caloric intake to fuel its size, metabolism, and thermoregulation in cold water, this strategy makes biological sense. Eating lean muscle when fatty tissue is available would be like filling up on celery when steak is on the table.
With sharks specifically, the liver is an outsized prize because sharks store so much of their energy there. A marine mammal distributes its fat across a thick blubber layer, so an orca eating a seal consumes the whole animal. A shark concentrates its fat in one giant organ, making it efficient for an orca to extract just that organ and move on to the next shark.
What Orca Diets Reveal About Their Nutritional Needs
Orcas have significant requirements for fat-soluble vitamins and essential fatty acids, which organ meats supply in abundance. The liver in most vertebrates is the primary storage site for vitamin A, and it contains high concentrations of other micronutrients. Research on orca blubber has found that vitamin A appears to be tightly regulated in their bodies regardless of diet or contaminant load, suggesting it plays critical physiological roles that the animals’ metabolism works hard to maintain.3Environmental Research. Are vitamins A and E associated with persistent organic pollutants and fatty acids in the blubber of highly contaminated killer whales (Orcinus orca) from Greenland?
Vitamin E, another fat-soluble vitamin found in organ tissue, showed more variability tied to diet. Orcas that fed more consistently on marine mammals in Arctic waters had different vitamin E profiles than those eating fish, and their vitamin E levels were more vulnerable to disruption by accumulated pollutants.3Environmental Research. Are vitamins A and E associated with persistent organic pollutants and fatty acids in the blubber of highly contaminated killer whales (Orcinus orca) from Greenland? This hints at why nutrient-dense organs like liver are so valuable: they supply vitamins and fatty acids that orcas cannot easily get from lean tissue. An orca that selectively eats liver is not just maximizing calories but potentially meeting specific micronutrient needs.
The Ecosystem Ripple Effects
When orcas kill and partially consume great white sharks, the consequences go well beyond one predator eating another. Great white sharks are themselves apex predators, and their absence reshapes the behavior and survival of the animals they normally eat. Research in South Africa’s False Bay found that when orcas pushed great white sharks out of the area, the pressure on Cape fur seals dropped. Without white sharks patrolling the waters around Seal Island, seals could forage more freely and faced fewer predation events.4PubMed Central. Killer whales redistribute white shark foraging pressure on seals
This kind of chain reaction, where removing a top predator releases pressure on the prey species below it, is a well-established pattern in ecology. What made the South African situation unusual was how quickly and dramatically it played out. The orcas did not need to kill every great white shark in the area. They only needed to kill enough, or be present enough, to trigger avoidance behavior in the remaining sharks. The effect was disproportionate to the number of sharks actually killed. Even a few attacks sent the white shark population packing, with downstream effects on seals, smaller sharks that white sharks normally suppress, and potentially the fish species those smaller sharks eat.
The partially consumed shark carcasses themselves play an ecological role. A large great white carcass, minus its liver but with hundreds of kilograms of muscle and cartilage still intact, sinks to the seafloor and becomes a food bonanza for deep-water scavengers. Hagfish, crabs, amphipods, and bottom-feeding sharks can feast on the remains for weeks. In this sense, the orcas’ wastefulness from a human perspective is a resource transfer from the surface food web to the deep-sea community.
The Physical Cost of Eating Sharks
Eating sharks comes with a penalty that orcas in other dietary niches do not pay. Shark skin is covered in dermal denticles, tiny tooth-like structures that make it feel like coarse sandpaper. Orcas that regularly eat sharks show dramatically more tooth wear than orcas that eat fish or marine mammals. Offshore killer whales in the northeastern Pacific, which frequently prey on sharks, have significantly greater apical (tip) tooth wear compared to resident and transient populations, and researchers have proposed that abrasion from dermal denticles is a major contributor.5ResearchGate / Aquatic Biology. Shark predation and tooth wear in a population of northeastern Pacific killer whales
Severe tooth wear can eventually grind orca teeth down to the gumline. This is functionally a big deal: orcas use their teeth to grip prey, not to chew, and worn teeth make it harder to hold onto large, struggling animals. The fact that offshore orcas persist with this diet despite the dental cost speaks to how nutritionally rewarding shark predation must be. If the caloric payoff from shark liver were not substantial, you would expect the behavior to be selected against over time. Instead, it persists, suggesting the energy gains outweigh the physical toll.
The selective consumption of liver rather than the entire shark may partly mitigate this cost. By extracting the liver through a single, targeted wound rather than consuming the whole carcass, the orca minimizes the total time its teeth spend in contact with abrasive shark skin. Eating the entire body would mean chewing through far more denticle-covered hide. Removing just the liver keeps contact time shorter and reduces cumulative tooth damage per feeding event, though over a lifetime of shark hunting, the wear still adds up visibly.
How This Behavior Spreads Between Orcas
Orcas are cultural animals. Different populations maintain distinct hunting traditions, vocalizations, and dietary specializations that are passed from mothers to calves. The liver-extraction technique appears to be no exception. In South Africa, the behavior became prominent when Port and Starboard arrived in the region. Other orcas in nearby waters do not consistently target great whites in the same way, suggesting this is a learned skill specific to certain individuals or lineages rather than a universal orca instinct.
This has important implications for how far the behavior might spread. If Port and Starboard interact with other orcas and those individuals observe and adopt the technique, liver-extracting shark hunts could become more common across the region. There is some evidence from other orca populations that novel foraging techniques can spread between pods over the course of a few generations, much as tool use spreads in primate communities. But if the behavior stays confined to one lineage, it could disappear entirely if those individuals die without passing it on.
The cultural dimension also explains why this seems like a “new” phenomenon even though orcas and great whites have shared oceans for millions of years. Orcas have always been capable of killing great whites. What may be relatively new, or at least newly documented, is a specific technique refined by particular individuals for maximum efficiency. The surgical extraction of a liver from a five-meter shark is not something an orca figures out on its first try. It is a practiced, transmitted skill, and its emergence in a specific time and place reflects the behavioral innovation of individual whales, not a species-wide evolutionary shift.
Why Not Eat the Whole Shark
The question is really about energy budgets. An orca can spend 20 minutes extracting a liver that delivers an enormous caloric return, or it can spend hours consuming an entire shark carcass, most of which is low-fat muscle and indigestible cartilage. If there are more sharks available, or other food sources nearby, the rational strategy is to take the best part and hunt again. This is the same logic behind why wolves sometimes eat only the organs of a fresh elk kill when prey is abundant, or why bears eat only the roe-filled bellies of spawning salmon when the river is thick with fish.
When prey is scarce, animals tend to consume more of each kill. When prey is abundant, they get selective. The orcas off South Africa had access to a population of great whites that, before the orcas arrived, was one of the densest on Earth. In that context, eating only the liver made perfect economic sense. Whether the same orcas would consume more of the carcass in a lean season is an open question, but the principle of optimal foraging predicts they would.
There is also a digestion angle. Shark muscle contains high levels of urea and trimethylamine oxide, compounds that sharks use for osmoregulation. These substances give shark meat its characteristic ammonia-like smell and taste when not properly processed. While orcas can certainly digest shark muscle, the liver is free of these compounds in high concentrations and consists almost entirely of easily digestible fats. For a predator that relies on efficient digestion to maintain its energy balance, the liver is simply a cleaner, more efficient fuel source than the rest of the animal.