Sharks: Facts and Myths
Sharks have millions of years of history behind them and they haven’t changed much since then.
In the minds of ours myths are mixed with reality, and we don’t differ facts from superstitions, and all this is because of usual human fear before the unknown.
Divers respect sharks as they are very smart animals, and at the same time are primitive predators. We admire and fear, while observing these creatures in their natural habitat, forcing divers again and again seek a meeting with them. If we add to diving with sharks a little more knowledge, it only increases its value and fun. Below are twenty real facts from the life of sharks:
- A large white shark grows about 25 centimeters in a year. Adult great white shark can have a length of more than 12 meters.
- More people die from the attacks of dogs, pigs and deer, than from attacks by sharks.
- Shark bite has a pressure of six and a half tons per square centimeter.
- Sharks change their teeth constantly, replacement of teeth of sharks occur at a frequency of once every eight days.
- During their life, some species of sharks can replace up to thirty thousand teeth.
- A whale shark has approximately three hundred rows of teeth. Each of these series contains hundreds of tiny teeth.
- Dried shark skin in the past was used as sandpaper. In Germany and Japan, shark skin was used in the decoration of handles of swords.
- In 1937 the discovery was made that shark visceral fat is very rich with vitamin A. For the production of vitamin A shark fishing was very active until 1950 – when was developed a method of synthesis of vitamin A.
- The typical life duration of sharks is 25 years. However, some sharks can live up to 100 years.
- Some sharks are called «dog», for their habit of attacking their prey in a pack, as do dogs.
- Great white sharks can live without food for up to three months.
- Not all types of sharks need to move constantly to breathe.
- Book sharks can live in water of varying salinity and can often be found in freshwater rivers and lakes in Africa and South America.
- The maximum size of Pygmy sharks is 30 cm.
- A shark has no bones. The skeleton of sharks consists of cartilage tissue.
- In the world there are over 340 known types of sharks.
- The first fossil traces of sharks date back over 400 million years.
- A significant difference between the modern sharks and shark antiquity is their longer jaw. It provides modern sharks with a much more bite force and makes them dangerous than their ancient predecessors.
- Shark skin is covered with leather similar to the teeth.
- The Mako Shark is probably the fastest creature in the world ocean: its speed can reach up to 100 – 120 kilometers per hour.