Contrary to what sensationalist movie makers would have us think, humans are not really part of the great white’s regular diet. Occasionally we’ll flounder around near the shore when the weather’s good but great whites generally prefer slightly deeper waters and, here’s the good part, fatter fish.
As the sole survivor of its genus, Charcharodon, meaning jagged tooth, this species has done well to beat the challenges faced by predators through a number of physical and behavioural adaptations. Both are necessary for feasting on the less fortunate members of the oceanic food chains. Great whites, like most sharks, are solitary creatures. The young leave their mothers immediately after birth and rely solely on instinct to hunt and capture their prey. Sharks hunt alone. Luckily, they’re well equipped for dealing with these circumstances.
Great whites, like most sharks, use gill slits to filter oxygen from the surrounding water. Consequently, their noses are used for smelling, never breathing, and are very efficient for this purpose. A layer of skin between the nostrils creates a one way system for water to pass through the nose in one nostril and out the other. Sharks “smell” the water by moving their heads from side to side, effectively forcing water through their nostrils. The water within this system passes over a number of highly sensitive olfactory cells which are directly linked to the brain’s olfactory bulb. This enables the sharks to smell pray from miles away.
The ampullae of Lorenzini are probably the most interesting of the great white’s adaptations to feeding. These little jelly filled holes covering the top and under side of the snout allow sharks to pick up tiny electrical vibrations created by moving animals. Although this type of sense is not unique to sharks it certainly gives them an advantage in sensing their prey, especially when that prey is hiding. Blood releases ions into the water enabling sharks to seek out wounded prey even more easily.
Great whites use smell and electro-detection to seek out their prey over vast distances. After that, it’s largely down to site. Evidence shows that great whites feed mainly in the day time but this is as likely to be due to the behaviour of their prey as to poorly developed eye sight. For example, when hunting seals, one of their favourite foods, they tend to hunt more often in the early hours of the morning, before sunrise. At this time the seals themselves are hunting in the surface waters. The sharks are able to make out the shadow of the seals on the surface but are concealed themselves, in the darker deeper water.
The great white will usually strike its prey from below. Seeing a seal floating on the surface it will swim furiously toward it, ramming and biting it at the same time. Its massive jaws are lined with three rows of serrated triangular teeth which help make up for its lack of jaw movement. A shark will often drag its prey into the water before releasing it. The stunned victim will usually bleed to death or drown. Seals have a high number of blood vessels surrounding the head area and bleed to death quickly when bitten around the head. Sea lions may not die as easily. If not, when the shark returns for its second strike it will usually finish the job.
As the shark thrashes its head from side to side, the prey is torn and sawn by serrated teeth. The teeth will often break off during this process and are swallowed. Not a problem for these beastslost teeth are quickly replaced by teeth from the inner rows. Chewing is a messy business for a shark and so it’s hugely advantageous to kill prey within the first two strikes. A misplaced bite can allow prey to escape with, hopefully, minor wounds.
The bite and release method of hunting has been used to account for the low number of fatal attacks on humans. The great white generally feeds on fatty animals such as tuna, mackerel, seals and sea lions. After the first bite the shark seems to sense that a human is not an adequate meal and will leave it at that
Great whites are at the top of their food chain along with the Orca whales. As young great whites eat rays and smaller fish. As adults they have been known to eat sea birds, dolphins, sea turtles, small toothed whales and other sharks, in addition to the creatures already mentioned. They may also scavenge off bigger whale carcasses.
A great white can last up to 2 months after a big meal. Then the hunt must begin again
