The great white shark is without doubt one of the most fascinating and mysterious fishes of the sea.. When a dorsal fin escapes from the surface of the water, the thought goes to this stately animal and conflicting feelings of attraction and terror born in the human mind.
The white shark in fact has always catalyzed man attention, representing one of the greatest raiders of which today science still ignores many aspects and behaviors.
Its movements and migrations are not known, for example the complexity of the social relationships with exemplary of the same kind, the abilities of learning and adaptation from past experiences..
Never have been filmed or photographed exemplary in phase of coupling and nothing of certain is known respect to the period and the preferred areas for the reproduction. It remains also a mystery the first years of life of a white shark, its moves, the strategies of defence by other greater raiders, the rhythms of growth..

   
White shark  (Carcharodon carcharias) and the particular teeth
 

The enormous interest toward this animal has made however to multiply, especially in the last 15 years, the countries of study and search, and some aspects of the biology of this shark have been clarified and surely brought to the light of the scientific community with amazing results:

1) Carcharodon carcharias is the only shark that brings the head out of the water to check better what it surrounds him and it uses therefore its acute sight also through the aerial environment.
This animal in fact can count on a good visual ability and it makes great trust on this sense. Not by chance, in the moment of the attack to a prey, the white shark protects his eye upsetting back them and he use his "sixth sense", that allows him to also individualize a prey without seeing her perceiving her elettro-magnetic field. (Note 1 - Ampullae Lorenzinii)

2) the white shark can sink him thin to arrive to around 1200 ms of depth showing a great adaptability to the variations of pressure, temperature and brightness of the environment in which he swims.
To oppose the variations of temperature of the oceanic waters to the various depths the white shark has developed a mechanism of heat maintenance that allows him to have a bodily temperature of 4 - 5 C to that of the water that surrounds him and up to 10 C as it regards the most inside musculature. This mechanism, the so-called "rete mirabilis", is common to all the components of the order Lamniformes, to which the white shark belongs. Further to a best adaptation to the temperatures of the external environment, the shark draws from the rete mirabilis great benefit as regards the times of digestion of the preys, that result faster immediately making available great quantity of energy. (Note 2 - Rete mirabilis)
With a temperature almost constant the white shark is able of mighty releases, to sustain elevated cruising speeds, and even of resounding jumps out of the water, when the attack to one prey of his is realized upward by the lower part.

3) this animal can live since 30 a 40 years. The small ones to the birth have a length of around 1,20 ms, their teeth are endowed with small side cusp and those of the inferior jaw are smooth rather than serrated. (Note 3 - white shark teeth)



White shark   (Carcharodon carcharias)
 

The behavior of an animal is often the only indicator that the Science has to understand its intellectual abilities.
To study the white shark in his natural environment is very difficult but a series of repeated strategies have let to the biologists, that have filmed them and analyzed, the following conclusions on the intellectual abilities of this great raider:
- the white shark is able of to manifest curiosity, that expresses with the careful exploration of what meets;
- the white shark possesses the ability "to investigate" new objects in systematic way, always maintaining a cautious behavior;
- he can learn to recognize objects not grocerieses using the memory of explorations done in past;
- it has the sense of the ownership and he can defend his sources of food in calculated way, also not violent; (es: during an attack to a surfer, in African waters, a white shark is repeatedly set among the body of the victim and a small raft that tried to recover the victim, preventing the contact of it and therefore the salvation)
- the white shark finally seems to have the ability to cooperate together to other samples of his same kind to optimize the predatory effectiveness; (es: in South Africa numerous white sharks would have been filmed during the attempt to move together the carcass of a whale in deeper waters)



White shark  (Carcharodon carcharias)
 

In base to these affirmations the white shark (Carcharodon carcharias) can be defined an intelligent animal, that possesses the ability to explore, to remember, to defend, all behaviors contemplated to an optimal survival and accordingly to a reproductive success, essential for the pursuance of the kind.

Predatory strategies and relations with the man: when a potential prey is identified by the white shark it begins the approach and the investigation.
In this phase the raider realizes what it is found before decreasing more and more the distance between the thin object and him to reach brief contacts, small hits with the nose and only sometimes immediate bites, to appraise the edibility of the possible prey.
If the "results" of his investigation are positive the attack happens, almost always from the lower part upward.. In this way the white shark makes him almost invisible, up to the last instant, in how much the bluish coloration of its back camouflages him with the color of the sea.
The prey finds stopped the opposite direction to that of the attack, that is the surface, and almost inevitably is overwhelmed and there is the bite, without way out..
Very often the speed of the attack and the emitted energy are so high that the body of the shark escape in part out of the water.
Immediately after the bite, the prey is momentarily abandoned, to avoid damages from a possible struggle with a dying animal, and the white shark remains to a certain distance, waiting the death arrivals..
After a brief period of time the raider returns on the place of the attack and devours its prey by now dead or without more strengths to oppose resistance..
As it regards the relationships with the man the white shark it surely results to be very dangerous even if the man doesn't reenter among his usual preys.
The 80% of the attacks not provoked to the man (Note 4 - provoked attacks and not) are concluded after the first bite, when probably the raider realized that the prey was not of his pleasure..
An only bite of the white shark is able however to provoke damages of serious entity, because of the strength and of the dimensions of this animal, and to bring equally to the death, especially in absence of immediate paramedics..



White shark  (Carcharodon carcharias)
 

White shark in captivity: the man has never succeeded in maintaining and therefore to study better a white shark in captivity, at least up to the year 2003..
It is important to understand that the study in captivity of an animal, whose presence in the waters of the world is drastically decreased, can serve to acquire greater awareness on the necessity of protection that it requires from the man. Examining its behaviors in captivity in fact the man try to fill those biological and ecological gaps that concern this shark and at the same time also the exposure to the public can contribute to cancel so many common places on the so-called one "men's eater"..
In June 2003 for the first time the Monterey Bay Aquarium in Monterey, California, has succeeded in maintaining in captivity a white shark for 10 days.
In September 2004 a female, captured for mistake by professional fishermen, is given to the aquarium and for 198 days this white shark perfectly suits her for the life in captivity and she is exposed to the public with great success.
In March 2005 this white shark, not to excessively prolong her permanence in captivity and to protect her from excessive stress, is released in open sea and studied for 30 days, aquiring in this way an important massive structure of data and biological information.
On August 31 st 2006 the Monterey Bay Aquarium holds in captivity another sample, which shows to have suited well for the new situation, normally feeding himself and increasing of weight and length.
On January 16 th 2007, after 137 days inside the aquarium, this shark is released, and thanks to the application of a satellitar tag (electronic signaller) that April 16 th 2007 is detached, all of its movements have been reconstructed in open sea within these three months. The shark has swum up to the south point in the Baja California, crossing more than 1000 km and reaching depth superior to the 300 m.

In the month of August 2007 a white shark is accidentally captured by the net of fishermen, in California, and he is brought to the Monterey Bay Aquarium, where the animal grows of weight and length for 162 days to be released in liberty in February 2008.  The last white shark that the Monterey Bay Aquarium has taken care has been in summer 2011: the animal as his predecessors, is regularly fed growing of dimensions and returned in liberty.

 
White shark  (Carcharodon carcharias)
 

 

White shark in nature: currently are two the principal destinations in the world that can be reached to observe the great white shark in nature: the region of Gansbaai and particularly the island of Dyer in South Africa and the area of Dangerous Reef, offshore the peninsula Eyre in southern Australia. 

1) Gansbaai is a small village of fishermen that is found to about two hours with car by the more note Cape Town (180 km of distance). 
The area is enough calm and what can offer is the beauty of its nature, and also the not scuba tourist can appreciate with long walks along the coasts. 
The white sharks can be seen in particular way near the island of Dyer, primarily sandy and distant few km from Gansbaai. 
In these zones there are, in fact, numerous seal colonies, together with their pups, appetizing preys for this great raider of the seas. 
As it regards the immersions, there are different centers that organize exits in sea with the metallic cage to see the white sharks, also recommend to the beginners, with the desire however to live strong emotions. 

White shark  (Carcharodon carcharias)

 

2) Dangerous Reef owes first of all the name not to the presence of the white sharks, but to the dangerousness of the zone for the navigations, near the Gulf of Spencer. This bluff is found offshore the peninsula Eyre, in southern Australia, also this zone populated from numerous seals, sea lions and therefore also white sharks. 
In this zone and in the near islets can be observed more than 12000 sea lions, the greatest colony in Australia. Also here the not scuba tourist can appreciate the beauty of the nature, the tones of the ocean and the beaches, both rocky and sandy, also participating in the exits of the organizations that transport the scuba divers in the various zones of immersion. 
Also the emerged earth in fact proposes his beauties, without forgetting, as already mentioned, the numerous seals and sea lions present in every islet of the zone. 
As it finally regards the immersions, also here they are realized with the aid of the metallic cages of protection, in surface for the beginners and on the fund for more experts.

White shark  (Carcharodon carcharias)

 

White shark  (Carcharodon carcharias)

 


Biological card of the white shark (Carcharodon carcharias):
 
WHITE SHARK
Carcharodon carcharias
LINNEO, 1758
Order: Lamniformes
Family: Lamnidae

Middle dimensions: 350-460 cms.
Maximum dimensions: it overcomes the 700 cms.
The greatest sample captured by the man was a female of 7,14 meters.
The white shark is drastically decreased of number in all the seas of the world and this has pushed many countries to declare him/ protected kind.
Description: shark of great dimensions, thick, with the pointed face. The mouth is ample the round and black eyes. The dorsal fins are two, her before averages dimensions, the dwarfish second. The pectoral fins are wide and falcades, while the caudal fin is symmetrical and to crescent. The white shark can reach the 60 km. also thanks to the possibility to maintain his muscles to a temperature of 10C superior to that of the water that surrounds him.
Distribution: in all the moderate and sub-tropical seas of the world, present in the Mediterranean sea. It is hypothesized the existence of a reproductive area between Sicily and Tunisia.
Coloration: grey-bluish back with clean passage to the white of the abdomen. Stung ax in the ventral part of the pectoral fins.
Reproduction: probably ovoviviparous (viviparous without placenta), unknown period of pregnancy.
Commercial value: object of sporting and commercial fishing for the liver, the skin, the fins, the carcass, the teeth and the jaws.
Teeth: triangular, astute, strongly serrated to the borders. The teeth of the superior jaws (from 23 to 28) and inferior (from 21 to 25) are very similar.
The scientific name can be translated in "dangerous shark for the man from the rough teeth". The small ones to the birth have teeth with side cusp and those of the inferior jaw are smooth.
Diet: sharks and races, bony fishes (tunas and fish-sword), molluscs, shellfishes, cefalopods, sea turtle, mammalian sea and carcasses of whales.

 

Teeth of white shark  (Carcharodon carcharias)

 


NOTE 1: The Ampullae of Lorenzinii are of the organs that take contact with the outside through small and numerous holes, present especially in the region of the head, full of a gelatinous conductor substance, in communication with nervous terminations. In this way the shark has the ability to perceive the electric fields produced by the animals (therefore to also individualize preys under the sand) and probably to recognize his own position in comparison to the earth magnetic field.

NOTE 2: The rete mirabilis is a whole of capillary that have the function of heat change, it is connected to muscular bands very develop, next to the vertebral column. Through the exchanges of heat of the admirable net the inside musculature of the white shark and the brain remain more warm temperatures of those of the surrounding water.

NOTE 3: The white shark teeth are unmistakable for its unique characteristics. They are great, triangular, astute, strongly serrated to the borders. The teeth of the jaws superior and inferior they are very similar.

NOTE 4: An attack to the man from a shark is defined not provoked when the animal is found in his natural environment and he has not suffered anybody stimulus or direct provocation from the man.
 

 

Bibliography: "Sharks & Rays, Elasmobranch Guide Of The World". Ralf M. Hennemann, "Sharks of the world", Leonard Compagno, M. Dando, S. Fowler, "The white shark", Jean Michel Cousteau, Mose Richards, "Sharks", Jeremy Stafford-Deitsch.

 

 

 

 

Marco Angelozzi - www.prionace.it

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