Great White Sharks are probably the most famous species of shark on Earth. From children's television programmes such as Sharkie and George and Kenny the Shark, to films such as Shark Tale or the monster sharks in the movie Deep Blue Sea, the White has captured the public's imagination. Yet it hasn't always been this way. In fact, prior to a series of attacks on humans in the summer of 1916, the media were largely ignorant of the big fish. These attacks by a possible lone shark patrolling the New Jersey shoreline, in which three adults and one child were killed, are described in Michael Capuzzo's book, Close to Shore, and helped influence the author Peter Benchley1 while he was writing his famous novel Jaws. This book and the subsequent box office hit movie, also called Jaws, had a dramatic effect on the public's perception of the animal. Benchley himself was so horrified by what he had done to the reputation of sharks that he became a spokesman on their behalf. Contrary to public perception, the White is not a mindless killer but an intelligent animal that is increasingly threatened by man's influences in the world's oceans.
- Kingdom: Animalia
- Phylum: Chordata
- Class: Chondrichthyes (rays, sharks and relatives)
- Subclass: Elasmobranchs (sharks and rays)
- Superorder: Euselachii (from the Greek eu - true and selachos - shark)
- Order: Lamniformes (mackerel sharks)
- Family: Lamnidae (mackerel sharks, porbeagles and white sharks)
- Genus: Carcharodon (from the Greek karcharos - sharpend and odious - teeth)
- Species: Carcharodon carcharias2
The Great White's family contains five members: the Porbeagle shark, the Salmon shark and the two species of Mako shark, the Short Fin and the Long Fin Mako. They all more or less look like small Great Whites and are probably often mistaken for them. However, the real monster of the family is the Great White's grandfather. Around three million years ago, the Carcharodon genus, which today only contains the Great White, used to contain another fearsome shark species: Carcharodon Megalodon. This enormous fish lived when there were many, many more species of whales in the seas and they were probably the reason it evolved: to eat them. At some 18 metres (60ft) in length and with teeth some 25cm (10 inches) long, the Megalodon makes the White look like a harmless little tropical guppy.
The Great White is very large. It is not the biggest shark in the world; that honour goes to the Whale Shark, followed by the Basking Shark. However, even its bronze medal position still makes it the largest predatory shark on Earth; the larger two species both being harmless plankton eaters. There has always been exaggeration over the White's size and fishermen are well known for their tales of the 'one that got away'. However, scientists generally agree that the White's torpedo-shaped body doesn't grow much bigger than a still impressive six metres (20ft) long. The problem with weighing the Whites that have been caught is that a single bite from a White can absorb around 14kg (30lb) of flesh, and it can gorge on several hundred kilograms of food in one sitting. Should the scientists weigh the shark with an empty stomach or a full stomach? It's a question that many people on a diet have asked themselves, but the general consensus is that a large White can easily weigh up to 1,900kg (4,200lb).
Teeth and Skin
White Sharks are infamous for their jaws. Thanks in large part to the film Jaws, the image of that bottomless pit filled with razor sharp teeth haunts us. The shark's mouth is indeed remarkable, as it is an extraordinary piece of evolution. Each White's mouth can contain up to 300 teeth, arranged into seven rows. These operate on a sort of conveyor belt system. Only the front two rows are used, to grab and slice prey. If a tooth breaks or is worn out, it falls out and a new tooth rotates forward ready for action. Sharks such as the Ragged Tooth Sharks may look fearsome but the long thin dagger-shaped teeth indicate they are mainly fish-eaters as the teeth are used for stabbing. The short triangular shape of the White's teeth, however, indicates that they are used more for grabbing and slicing and therefore are much better adapted for larger prey, such as seals. The mouth of a White is highly tactile as the base of each tooth contains a mass of nerve endings; there are more nerve endings under a single tooth than on a human finger tip. This sensory wonderland enables the shark to use its mouth to 'test' the nutritional suitability of a prey item.
White Shark skin does not have scales like other fish; instead it is made up of thousands of microscopic denticles. As the word implies, these denticles look very similar to a White's teeth but they all lie flat along its body with the point towards its tail. This arrangement ensures that the shark's body is streamlined. If you were to run your hand along the skin in the nose-to-tail direction the skin would feel smooth as silk; if, however, you were to rub it in the opposite direction, from tail to nose, the denticles would be raised upwards making the skin feel like sandpaper.
Although named the Great White Shark, none of them are pure white. All white sharks have a pale underbelly while the top half is dark. The actual colour can vary depending on the region it comes from: Californian sharks are a very dark slate-grey, almost black, while South African sharks often appear to be dun or olive-coloured like Australian sharks.
The White is an incredible predator and can famously smell a drop of blood in 100 litres (25 gallons) of water. What is less well-known is their good sense of colour vision which they use while hunting, right up until the last second before a bite; then they roll their eyeballs back into their head to prevent damaging them. In common with many sharks, Whites also have what appears to be a 'sixth sense'. The Ampullae of Lorenzin are a series of jelly-filled pores on the shark's skin. At the base of each pore is an electroreceptor cell. By judging the voltage difference between the top of the pore and the base the shark is able to detect electrical signals in the water. As all animals produce electrical charges in their muscles, the shark is able to detect these movements and use it to hunt. This sense is so sensitive that it can detect voltages as low as 5/1,000,000,000 of a volt.
The White also has a good sense of taste. In fact, in most of the harmful encounters that Whites have had with humans the shark was never attacking the victim. If a human was deliberately attacked with the full force of a hunting strike the chances of survival would be very slim indeed. The number of people who have survived White Shark attacks indicates that the shark was merely carrying out a 'test bite'. This is when a White will mouth a strange object in the water to taste it and see if it is edible. Unfortunately for any humans involved in a 'test bite,' the pressure at the point of the White's teeth can be as much as several tonnes - this could mean the victim losing a limb or even dying from blood loss.
Behaviour and Brains
How do you measure the intelligence of a fish? Admittedly it is hard, but certain things can be inferred from their biology and behaviour. Unlike most fish, White's aren't purely cold-blooded. In fact, they can control the blood temperature to their vital organs such as the heart, stomach and brain. This infers that they are using their brain a lot, and it's not there just as a dumb processor unit. This does seem logical as land-based predators such as lions do tend to be more intelligent than the herds of wildebeest on which they hunt. We can also see the White's intelligence in its behaviour, unlike the shark in Jaws which was made out to be a loner, hungry for humans. The White is actually quite a sociable character. They exhibit pecking orders when it comes to scavenging large carcasses, with the largest Whites having priority over the smaller sharks, much as is the case in a wolf pack. Whites are also known to have different swimming patterns which relate to keeping their own personal space, such as cautiously-timed 'turn-aways' between two animals coming into line with one another. Similarly, Whites have been known to roll on to their backs much like dogs do when trying to act submissive. In White Shark language the deeper in the water a shark is the more aggression it is exhibiting as this is the natural position for the hunting shark. It has been observed that when a smaller White comes across a larger one from below it will half roll onto its back; this submissive posturing is used to defuse what could be construed as an aggressive action.
On the other side of the coin, a White will open and close its mouth when trying to be dominant or aggressive. In much the same manner as a dog will growl and shows off its teeth, the White also shows off its own set of formidable weapons. Unlike many species of shark, though, the White does not use its body posture to show aggression. Many reef sharks lower their pectoral fins and arch their backs when being aggressive; a White, however, only uses its pectoral fins for fine control of its body position when swimming. Whites are also one of the few shark species known to have been seen 'spy-hopping'. This curious behaviour is when a shark will deliberately raise its head up out of the water. It's not known exactly why the shark does this. It may be in order to look for prey, but it's debatable whether the good vision the shark has underwater can focus clearly in the air, much in the same way as we cannot see very well underwater. It's more likely that the shark is sniffing the air currents to find out what is around it.
Humans do not make up any part of a White Shark's diet. The human body is too bony and we are not fat enough. High energy fat, or blubber, is what makes a meal worth hunting. Instead, Whites prey on seals, sea lions, turtles, sea birds, fish and other sharks. They have also been known to scavenge on whale carcasses and other dead animals found floating in the sea. Whites are primarily ambush hunters. They lurk in deep dark water waiting for the right moment. When it sees a potential meal swim past, the White will use its caudal fin to power its two tonne bulk up to 25mph and punch into its prey with a massive bite and retreat. This technique can result in overkill, severing a 250kg seal in half. Once the combination of blood loss and shock has subdued the victim, the shark will come back in to feed.
In some regions, Whites have developed a hunting trick of springing ambushes from the sea bed. When the White sees its prey swimming above, the enormous force of the impact can lift even a big shark clean out of the water. These breaching attacks are one of the most spectacular sights in nature. Yet, as is often the case in nature, the sharks don't always have it their own way. Many seals have learned to adapt to the White's hunting behaviour. Instead of swimming on the surface, the older and wiser seals dive down to the same depth as the Whites. Here, the ambusher doesn't have the depth that enables it to build up the speed for one of these breaching strikes. It is also rare to see a White that hasn't sustained some form of injury from hunting. Seals in particular can be large, strong animals and many a White has been seen with deep scars resulting from the claws and teeth of a seal fighting to escape3.
Population and Distribution
Whites live in almost all coastal temperate waters. They can be found in water as shallow as three feet deep, and as deep as 1,280 metres. Some animals appear to be very regionalised and spend a long time in one area while others have been known to travel huge distances. In fact, one female White affectionately known as Nicole4 was tagged off the coast of South Africa with a satellite tagging system; she proceeded to swim 11,000 kilometres to the west coast of Australia in 99 days. She then turned around and swam back again! Whites can be found on the coastlines of the eastern USA, most of the Gulf coast, Hawaii, most of South America, New Zealand, the Mediterranean Sea, Japan and the eastern coastline of China to Russia. The highest population densities are to be found around the west coast of the USA, especially California; in Australia, especially on the southern coast; and around the Cape of South Africa. In fact, the world's highest population density is around the South African town of Gaansbai where Michael Scholl of White Shark Trust once counted 31 sharks in a single day. However, the White is still rare worldwide; due to its oceanic lifestyle, counting populations is very difficult and even regional figures are sketchy at best.
Breeding and Life Span
There is still much to learn about the White's mating rituals and the birth of this species. What is known from examining pregnant females is that Whites are ovoviviparous, which means that the eggs develop and hatch in the female's uterus. The young fend for themselves; there is no placenta through which to feed, so they eat the unfertilised eggs and smaller siblings in the womb and continue developing until they are born. This is unlike most fish and many other shark species which just lay the eggs in the sea and hatch out very small. Instead, when a White is born it will already be some 1.5m (5ft) long, and already be a perfectly capable predator. Even so, when the young are born the mother shark does not help them; instead they swim away to live on their own. Each of these baby sharks will grow by about 25cm (ten inches) each year, attaining two metres in length within their first year of life and reaching maturity at ten years. A White can reproduce when a male's length is around 3.8 metres and a female's length is around 4.5 to five metres. Their lifespan is not known, but is estimated to be 14 to 15 years.
Threats to the Species
Scientists believe that most sharks are in major danger because they appear to inhabit only 10% of the world's oceans. This is perhaps especially true of the White Shark which was first protected in South African Waters in 1991 and then given worldwide CITES II protection in 2004. Organisations are being set up such as the Shark Trust which are helping to eradicate the threats below that the Whites are currently encountering.
Many reasons exist behind the act of shark fishing: their skin is used as leather, teeth and bone for ornaments, liver oil in cosmetics and aircraft industries, whereas cartilage is used in cancer 'treatments' and their fins create food. However, the White Shark itself has never really been the target of commercial fishing. Instead, they have been the target of recreational trophy hunters aiming to get a set of the famous jaws to mount on their wall. Equally, the shark's teeth are often taken to be made into the centrepiece of a necklace. The unfortunate irony here is that many of these necklaces are bought by people who strongly favour White Shark conservation and have no knowledge that the teeth have been forcibly taken from a dead fish.
Every year as many as 100 million smaller shark species are slaughtered to make shark fin soup, a delicacy usually eaten at special occasions such as birthdays and weddings. It even had an on-screen appearance in the film Crouching Tiger, Hidden Dragon when the governor's daughter, Jen Yu, ordered shark fin soup upon sitting down at a restaurant. The value of the fins is so large compared to the rest of the shark5 that in some cases there have even been reports of fisherman cutting fins off live sharks and throwing the poor creatures back into the sea. Unfortunately for Whites, these smaller shark species that are affected by commercial fishing make up a large part of its diet. The effect of this large-scale unsustainable slaughter of different species can have serious effects on completely different species up and down the food chain.
White Sharks have also been a victim of the media's portrayal of them as killers. There have been frequent calls for the culling of Whites often after news reports on the latest shark attack that may not have even been carried out by a White. They are, though, big, powerful and dangerous fish and as humans have increasingly used the water for leisure Whites have come into contact with humans more and more. This has led to some places mooring 'shark nets' such as the ones along the South African Kwazulu/Natal coast. Unfortunately, while they may prevent many incidents, they are not foolproof. Whites have been seen swimming inside the nets and they can often trap and cause a shark to die as it becomes trapped and entangled.
For centuries, humans have been using the oceans as a refuse site to dump their waste in. As a result, all life in the oceans, including sharks and their prey, have been polluted. Like many other animals at the top of the food chain, sharks consume prey that has stored up so much toxic material in their tissues that they actually become poisonous. The long-term effects of this type of pollution on sharks are unknown. Sharks are slow-growing animals; a single female shark produces only a few hundred pups or less in a lifetime. If the shark's population continues to suffer from the effects of pollution and other man-made problems like over-fishing, it may take years to recover, and certain species of shark may disappear forever.
Tourism can perhaps be seen as one of the best ways of helping ensure the survival of the White Shark. By allowing more people to see a White Shark in its natural environment, rather than just on the television or cinema screen, more people will come to view the White as a beautiful and amazing creature. In the end the shark will gain more and more supporters which can only be a good thing for its survival. It is similar with the rhinos in the safari parks of Africa where tourism has enabled some of the parks to really make a difference in rhino conservation by providing support, publicity and finances. One of the greatest ways to see a White Shark is from a cage diving boat. This can be from the deck, or for the more adventurous, from within a steel cage that is lowered into the sea and it allows the viewer to see the shark up close in the water.
Being in a cage with a White Shark was one of the most amazing things I have ever done. It gracefully cruised past me and left me in no doubt that it was intelligent. I didn't feel threatened in the slightest as it looked right at me with a curious and inquisitive stare. I could almost see it thinking...what are you?
- A Researcher's experience of cage-diving with Whites.
This is a tourist industry in its infancy and it has attracted some criticism and controversy. On the one hand some people believe that cage-diving negatively effects sharks. This is because sharks and humans don't usually interact with one another and they believe over time sharks will adapt their behaviour towards humans. They also argue about the use of the chum, a nasty concoction of mashed up fish and sea water that dive boats use to attract the Whites to the boats. They say that by encouraging the sharks into associating humans with food they are increasing the likelihood of a shark attacking a person.
As with any industry there are counter arguments - all dive boats should only use chum in areas in which Whites are known to actively patrol anyway, and these should be far enough away from human leisure areas so as not to draw the sharks towards them. Also, responsible dive operators will not feed the sharks; only sharks that are willing to scavenge will follow the chum trail, and if they find no food at the end then the shark will soon swim off and not associate chum with a meal. Unfortunately, there are always some bad tour operators that do not do this and this is where government licensing can help weed out the good from the bad. It's in the areas of finance that the shark tourist industry can seriously help conserve the animal. Ultimately for the poor fisherman it is money that is the ultimate decider; a single set of White jaws can fetch up to £20,000, a very tempting amount of money for a day's fishing. However, if this figure is compared to the dive industry in Gaansbai South Africa, for example, viewing a live shark can become much more valuable to the local population. There are about six boat operators in Gaansbai, each boat taking around 30 people out to sea a day and each person will be paying anywhere between £50 to £150. So in a single day a solitary live shark that visits each boat in turn can create anywhere between £9,000 to £27,000 of income every day!
The best places to see the Great White Shark in the wild are the Farallon Islands6, Dyer Island near to Gaansbai in South Africa and in the Southern Australian Ocean off Adelaide and Port Lincoln. As well as being great holiday destinations, these places enable holidaymakers to get close and personal with the sharks allowing for a memorable experience.
As more and more people conquer their fears about sharks and begin to understand them we begin to understand and learn more about these magnificent animals. In fact some experts are now using their knowledge to develop even closer interactions with the animals that should further our understanding of them before it is too late.