GREAT WHITE SHARK FACTS

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Many shark attacks on man have proved to be the work of the great white shark. This positive identification has been made from tooth fragments recovered from shattered surf boards and damaged boats.

The great white shark is a great prize for a rod and line fisherman, who consider them to be the ultimate in catches. They are recognised by their dorsal fin - which is high and distinctly triangular, and the crescent-shaped, powerful tail.

Sharks are killed for their sport and for their meat which is said to be tasty. However, they do retain high levels of urea in their body tissue which may be off-putting to some.

There is much mythology surrounding the great white shark in the Pacific Islands. A particularly large specimen is said to be the 'shark god' which rules the oceans and comes out of the depths to appear to the natives.

Remarkably, few facts are known about the great white shark. Attempts to study it in its natural environment have failed because of its rarity - and the fact that it is constantly on the move. It has also proved impossible to keep - and therefore study - in captivity.

Great white shark facts

1. A large great white shark can bite at a power ratio of several tonnes per square centimetre.

2. Great white sharks are able to scent a single drop of blood in 4,600,000 litres of water.

3. The great white shark must maintain a cruising speed of 3.5 km/h.

4. If a great white shark is dragged through the water backwards through the water, it can drown in minutes.

5. They can see in the day and at night and can see colour. However, they don't have eyelids, but instead can roll their eyes back to protect them.

6. Their bodies are counter-shaded with a charcoal to black, grey or even dark brown top (dorsal surface) and completely white underneath (ventral surface). Yhis counter-shading makes it difficult for their prey to see them

Great white shark teeth

The triangular shaped teeth each measuring up to 7.5 cm all have serrated edges for gripping prey.

Like all sharks, great white sharks can replace lost or broken teeth.

These grow on a band-saw principle lying dormant in the jaw until required.

When a tooth is lost, the band turns and a new one appears.

When the shark bites into its prey, it shakes its head side-to-side, helping the teeth saw off large chunks of flesh

Great white shark habits

Scientists believe that beyond a certain length-to-weight scale, a great white shark will make a total habitat change. It would seem that specimens which have happily survived in the upper ocean layers abruptly forsake their natural haunts and vanish forever into the dark depths below.

It is also though possible that - like the wrasse and blue marlin - the great white shark may undergo a sex change, reverting from male to female when they get to a certain size. It is not known just why this happens. It may be natures way of ensuring the perpetuation of the species. the logic behind this being that a large, healthy shark has a better chance of of giving birth to healthy young when compared to a smaller weaker specimen.

Certainly, the majority of all large great white sharks have been female.

What does the great white shark eat?

As you would imagine, just about any living creature in the ocean is possible prey for the great white shark - and the larger it is, the better!

Tuna, marlin and broad-bill swordfish are amongst the great white sharks favourites, while sea lions, seals and dolphins will all make acceptable snacks.

Most great white sharks hunt alone, although a number may home in together on dead prey after blood has been released into the water after a kill.

No actual figures are available of just how much a shark will eat in a day for it will depend on each individual shark and what prey is available in the vicinity as well as the temperature of the water.

They tend to take more food in warmer waters, where their metabolic rate increases.

It is thought that the great white shark will feed at any time it comes across prey, regardless of whether it has just had a big meal or not. It can then last for some considerable time - a month or so - without any food at all if need be!

Vital to the great white sharks hunting success is its acute sense of smell, because scenting prey in the water is the sharks primary tool for finding its food.

Within the great white sharks nose-cone are thousands of tiny pin holes which make up the sharks main nerve centre.

Because of its highly developed sense of smell it is able to detect and locate minute amounts of blood in the water.

It is also believed that the great white shake possesses some form of echo-location which it uses to help locate its prey.

Great white shark reproduction