The great white shark is the undisputed ruler of the seas. Once it reaches adulthood, a great white shark will face a significant threat only from humans. In order to make it to the top, a predator must have an effective hunting method. As juveniles, a great white’s diet mostly consists of fish, but as the shark approaches maturity they mostly subsist on marine mammals such as seals and sea lions.
Great whites do not have a single normal body temperature like mammals and birds, so they cannot be considered true warm blooded animals. However, great whites are able to maintain a varying body temperature warmer than the surrounding water. This adaptation allows them to move quickly in cold conditions, but in order to fuel their internal furnace a great white shark needs huge amounts of calories, so great whites must eat significantly more often than most other fish. The fatty blubber of marine mammals is rich in calories, and as such great whites have adapted ways to capture these swift animals.
First and foremost, a great white must have good timing. Most hunt early in the morning, when the seals wake up and swim off shore to feed. The seal must travel between the shore and the shallower areas that are home to small fish. A great white will usually hunt in the deeper channel in between. The water is murky early in the morning, but this works to a shark’s advantage. The seal must stay near the surface, as they need air. A seal would be hard pressed to look down and see a shark against the dark waters below, but a shark can look up and see the seal clearly silhouetted above them. In addition, a shark has highly tuned senses of smell and hearing, as well as a sense we humans do not share with them: the ability to detect electrical disturbances generated by the muscles of organisms. Combined with the murky water, this gives the shark the predatory equivalent of a sniper scope.
Though great whites are both agile and strong, they are ambush predators, relying on the element of surprise. Depending on the prey, the hunting method will vary, but the beginning is the same for any situation. The shark positions itself directly beneath the prey and shoots upward, quickly gathering speeds of up to 25 miles per hour. It strikes a single massive blow, ripping into its prey with hundreds of 2 inch long teeth, the edges of which are serrated, like steak knives. It is difficult to conceive the power of that first bite. A great white can weigh over a ton. Being hit by a great white from below would be similar to being hit by a mid-sized sedan moving at 25 miles per hour, except this car has a set of jaws bristling with daggers mounted on its front fender.
This is where the method starts to change depending on the prey. For smaller prey, like harbor seals, the shark simply grabs the prey and drags it below the surface. The animal will either drown or go into shock and die, at which time the shark consumes it near the bottom. In the case of larger animals, such as elephant seals, the shark delivers a massive bite to the hind end of the animal, crippling it. The shark then moves to a safe distance and waits for the seal to bleed to death. It may seem at odds with the Hollywood image of the great white ripping chunks of flesh from its still-living prey, however, it makes sense from an evolutionary standpoint. A bull elephant seal can weigh as much or more than a great white; after all, why risk injury fighting a huge animal when you can hinder it and inflict a mortal wound with one bite, then simply wait on the sidelines for it to die? Great whites will not pass up an easy meal, however. They have been filmed scavenging off whale carcasses.
The great white’s method of hunting is believed to be the cause of most of the recorded attacks on humans. A great white can sense the mammal above it, but it cannot clearly see what type of mammal it is sensing. By the time the shark can properly distinguish what kind of animal it is bearing down on, it is already too close and moving too fast for it to stop. Often, the shark will take a single bite and then swim off upon realizing that a human being is not, in fact, a seal. Unfortunately, as described before, the first bite is often all it takes. More often than not, the cause of death in an attack by a great white is blood loss, not the shark tearing the person to pieces
These facts are interesting in and of themselves, but they also can be used to help prevent attacks on humans by great white sharks. Firstly, if you see seals swimming where you intend to swim, there may be whites below, hunting. Secondly, avoid swimming at dawn, when sharks are most active. In addition, avoid deep, murky water, as most sharks prefer these conditions for hunting and will also not be able to tell that you are not dinner. Great white sharks are majestic and amazing animals, and understanding how they catch their prey is of pivotal importance to understanding how we might preserve them. It also gives us the added bonus, however, of teaching us how to stay off their menu.
