El White shark It is a species commonly associated with the murder of people in the sea, however, this is a species that does not really have people among its usual prey, they have another type of food, which will be explained in this post along with some characteristics , its reproduction, among other things.
White shark
The white shark is part of the family lamnidae and it is found mostly in temperate or warm waters that are distributed throughout the world (or the oceans to cover their real habitat), they really live near things and in waters that are not very deep, where there is a lot of light and the sea currents are enough. These types of places are home to a lot of marine life, which is an advantage for great white sharks.
Even so, these are solitary animals that travel a lot because they can stay warmer than the water that surrounds them due to their evolved metabolism, however, they do not approach oceans such as the Antarctic or the Arctic, but they can reach waters that have more than 1000 meters deep and they go down without problems. You can make a list of the places where these specimens have been observed most frequently:
- Beginning with the Lesser Antilles and certain parts of the Greater Antilles
- Also in the Gulf of Mexico
- Florida St
- Cuba
- The east coast of the USA
- Terranova
- The coast of Rio Grande do Sul
- Patagonia
- The Pacific Coast of North America
- In archipelagos such as Hawaii and Fiji
- In all of Australia except in the north of its coast
- They are also found in Tasmania
- On the well-known Great Barrier Reef found in the Coral Sea in northeast Australia
- in Hainan
- Japan
- Sakhalin Island
- On the coast that stretches from Senegal to England
- In the Cape Verde Islands and the Canary Islands
- As well as in the Mediterranean Sea
- in the Balearic Islands
- The Pitiusas Islands
- The columbrete islands
- In the north of Catalonia
- In Andalucia
- In Castellón
- They sometimes frequent the waters of Malaysia and Indonesia.
Also, they are part of the animals that migrate but the reason is unknown, but this is not the only thing that is unknown about this species, details about their mating are also unknown and research is still being carried out on their genes. Some aspects are unknown to them for being a genre that has been around the world for many years and has very ancient descendants. What you can answer that is how dangerous it is to approach them and how complex it can be to keep them in captivity.
The white shark is a species that has been part of several film productions that portray it as a character that kills in the sea, but the stories on which they are based seem to indicate that the attacks are not carried out by a single specimen and neither It is not even the same species, it may be several sharks.
Many films have generated a negative idea of these animals, a perspective of terror beyond that of a preventive attitude towards them. This is something quite frequent in audiovisual productions transmitted in the different media, the stereotypes and clichés that are created from the image projected on the screen are numerous and largely negative. Among the productions where the presence of a white shark has been dangerously highlighted are:
- Jaws – 1975: based on a novel by an anonymous author in 1974 and on the references of a ship sunk in 1945 in the Pacific. A film with a great social impact that was measured in the number of cases of people who claimed to have aquaphobia, in addition to the reduction in the influx of tourists on the beaches days after the premiere of this work, added to that the fishing of sharks.
- Tiburón 2 – 1978: the sequel to that shocking first production, with the same protagonist.
- Shark 3 – 1981: in this installment the shark that attacks is a female specimen that protects her young, the protagonist in Martin Brody's firstborn.
- Shark, revenge – 1987: the protagonist in this story was the widow of Martin Brody
- Shark Attack – 1999: A play recounting several shark attacks in a village in Africa
- Finding Nemo – 2003: Shows a comical image of a great white shark helping another fish (which is part of his diet) to find his son
- El espantatiburones 2004: It is another production that has many more characters embodied in sharks of other species, the image is a little softer and more humorous.
- Deep Blue Sea – 1999: it is a production that does not refer to white sharks but to tigers and bulls.
Evolution
The story of the evolution of this species begins with the discovery of the oldest white shark fossil found so far, it was large compared to today's specimens. This discovery worked to relate it to the mako shark or short-finned shark that is part of the family lamnidae, however, other paleontologists relate it to Cretolamma Carcharodon.
Other scientists relate it to the Megalodon, which is a presumably extinct species that measured up to 30 meters in length, this species, in fact, has a similar name: Carcharocles Megalodon and is part of the class Chondrichthyes and gender carcharocles just as the white shark is part of the same class but of the genus Carcharodon. Both species are part of the order Lamniformes.
In fact, for the studies on the real size of the Megalodon, the size of the white shark was taken into account due to its relationship and kinship, assuming that the size of the first exceeded the second 10 times. However, there is more evidence in the fossils found of the megalodon, the mako and the great white shark that links the last two much more.
Regarding the taxonomy of the white shark, it can be started by saying that its denomination as carcharodon is a generic name placed before the term was added to it carcharias to its current scientific name. Its common name may be white shark or great white shark, this because as they age their belly tones go from black to gray and then to white, in addition to that as they age they become larger, that's why the "great".
In any case, it is a species that belongs to the class Chondrichthyes and it really is one of the marine animals with the oldest lineage studied so far. It is estimated that it exists since the Neogene period, specifically in the Miocene. Its ancestry is debated between the Megalodon species and the mako shark.
Features
White sharks are quite robust, they have a flattened shape compared to other sharks but they are quite large, with a very large arch-shaped mouth that makes it very easy for them to feed, in addition to that they keep it mostly ajar showing an upper row of teeth and a lower one, which leads to the questionHow many teeth does a shark have? if you see his mouth really open.
Opening it actually deforms its head a bit because its jaw "projects" allowing a fairly large opening to be reached, when biting the force can be estimated at 12 to 24 tons. As for their teeth, these are quite large, they have a triangular shape, they are wide and they differ from other sharks in that none of them are reduced, they are all aligned in two main rows and one secondary, the teeth that are They fall or break over time.
Its eyes and nostrils are small compared to the rest of its body, it has five gill slits on each side, two large and two small pectoral fins plus a well-developed tail fin, in addition to that it has two small fins near its tail.
Regarding their color, they are really gray and some black, only one white shark was albino and it was a very small female. The rest of the white sharks have gray or blue-toned dorsal fins, while their bellies are white, they have black armpits.
They have receptor endings near their nostrils that allow them to detect electrical fields, which tend to disorient them. As for their sense of smell, this is quite powerful and can detect blood several kilometers away, which makes them quite aggressive.
Their sense of sight is also quite developed and allows them to approach their prey very skillfully. Studies conclude that their sight is green and that they have a range of vision similar to that of humans (straight) even though their eyes are on the sides.
A curious fact is that some specimens are attracted by electric fields, a specimen that was kept in an aquarium in the city of San Francisco hit a wall that had an electric field of 125 microvolts.
The size of these animals is from 5 to 7,5 meters when they are adults, the females are mostly the ones that reach that size limit because the males are a little smaller than them. Even so, some specimens found may have a larger size, so an average of its size is given, but an exact maximum cannot be placed, in the book of world records there is the record of two great white sharks that measured 9 meters one and 11 meters the other.
However, these measurements do not seem to be the correct ones, so the initially exposed estimate is maintained, a case records the appearance of a white shark in Cuba in 1945 that measured 6,4 meters in length and weighed 3270 kilograms. The six meters seem to be the estimated growth of a mature specimen, since when verifying the measurements of the captured specimens, they do not exceed six meters. This is why there is a current consensus that places this measure as the average.
While the 1.9 tons of weight would be the maximum that a shark of this species could have. However, when talking about the weight, it is important to highlight that it is a point that can vary because it depends on the diet that each specimen has and even if it has eaten recently. An adult white shark can easily weigh two tons, although the specimen with the largest weight did not exceed 1.75 tons.
Adaptive aspects of the white shark
Two important points position this species above others in terms of its natural ability to overcome certain situations, the first of which is cancer and the second is its ability to heal and the resistance of its skin.
As for cancer and sharks, their ability to prevent tumors from forming in their cells is known, this is because cancer starts and develops easily in those organisms that have cellular instability, white sharks are the opposite, they have a certain stability in their genome that responds very well against tumor processes, they repair the damage that occurs in the DNA because they have more genes that are dedicated to repairing it, something in which they surpass the human being.
These studies have allowed the creation of culture media created from the tissue of sharks, however, research continues in this regard. This may seem like a really positive thing to improve human life expectancy, but it harms the life expectancy of this species, assuming that various substances based on shark tissue are developed, their disappearance may be something that increases and ends once and for all all with their existence, for having "a good reason."
Regarding the second point, something to note about the skin of these sharks is that it is quite hard compared to that of other animals, this is because the keratinization of the skin of sharks is quite high, which protects them from superficial injuries. . In addition to that, they have scales with a shape that keeps them overlapping to reduce the friction they have with the environment that surrounds them, this, in addition to protecting them, gives them greater speed in their swim and requires less energy use.
Their genes play an important role again, because they allow them to produce a protein from the keratin family that favors the healing of their wounds, in addition to other training processes that are more easily carried out by them.
Food
White sharks eat mostly marine mammals when they are adults, in addition to that they usually feed on bluefin tuna, cetaceans, preferably the monk seal and even sea turtles, they usually prepare their ambushes at dawn or dusk, waiting for the prey Several meters below it, as they have a dark color they can camouflage themselves until they consider that the time has come to attack with speed and swim towards them to open their mouths and eat them.
When attacking they can immediately kill prey that are small in size, when they are larger they usually bite them first and tear off a part of them. Since they cannot chew, they usually swallow their prey whole after several pieces have been ripped off.
In addition to the species mentioned above, they usually eat carrion and when they are on the coast they can eat anything that is floating near them by accident, the rest they eat seals, sea lions, rays, porpoises, dolphins, beaked whales, sea lions, sperm whales , pilot whales, penguins and otters.
Now, they are usually food for killer whales, so this species would be their natural enemy. This has been known since 1997 when the death of a great white shark was recorded in the Farallón Islands, which was produced by a female orca that measured approximately 6 and a half meters. However, orca attacks on sharks are not common against older white sharks, orcas usually attack those that are younger and smaller.
They may attack each other as part of a fight for prey, as killer whales and sharks have a fairly similar dietary diet. In any case, in a place where there are killer whales, there will be no white sharks and perhaps no other type. Something curious is that tiger sharks and bull sharks are not only aggressive with their prey and with humans, they are also aggressive with sharks of other species such as whites, so it is possible to see these species attack each other.
Reproduction
White sharks are ovoviviparous, that is, they form eggs inside the female's body and only come out when the embryo has completed its development. These embryos are called oophages and can remain in their mother's uterus for 4 to 14 weeks. It happens that when they are ready to leave, the strongest offspring tend to eat the eggs of their weaker siblings while still inside their mother's uterus, this is called intrauterine cannibalism and occurs in several species.
Female white sharks can develop three or four pups inside them that can measure 12 decimeters in length, when they come out of their interior they move away from her because some tend to eat them when they stay close. They don't really hold together, taking into account how sharks are born From the moment they are completely outside, they move away and live alone while they are growing.
This growth is fast compared to other species, they can reach two meters when they have not yet completed a year in the world. The females always grow more than the males, however, they mature sexually before them, some scientists relate their sexual maturity to the size they reach, but some specimens are already sexually mature at two and a half meters, although many of them are how much they are almost 4 meters long.
The females reach sexual maturity when they are more than four meters long and even when they reach 5 m, their fertility is still under debate because there have been few discoveries in this regard, the truth is that it should not last long because its rate reproduction is low. In any case, it is possible to differentiate the females from the males by the pelvic fins that they have and that function as copulatory organs.
Mating
The mating of white sharks is not an act that has been able to be studied by biologists, however, the testimony of a New Zealand fisherman given to a Canadian biologist recounts the mating of two white sharks in Port Charlmers. This occurred in waters that were no more than four meters deep, they measured approximately four meters long each and according to the fisherman:
“Simply turning in slow circles”, without leaving the place. “They rolled and rolled and rolled, pressed very close together and just spinning over and over again very, very slowly."
This testimony seems to coincide with the way in which other sharks mate, however it is not known in detail how they do it, how courtship takes place, in which areas they prefer to do it (although it is believed that they prefer to do it in warm waters at the time spring or summer), how long they take to do it, what type of females and males do it (big, small, mature, young), really little is known about this species because of how difficult it can be to approach them.
Life expectancy
Previously it was believed that white sharks could live between 15 and 30 years if they maintained a normal diet and without any complications, however, an investigation was carried out in 2014 with a group of sharks that included four males and four females, this was northwest of the Atlantic. Here the researchers concluded that white sharks could live much longer than previously estimated.
They could live between 70 and 80 years, since one of the specimens was 73 years old, the oldest of the three males. While one female was 40 years old and the rest were much younger. This indicates that they can remain in the sea for a long time, approaching very close to the average lifespan of human beings.
This is clearly influenced by the conservation status of these animals, logically the Endangered animals in the world they have a (mostly) very short life expectancy, the infrequency of their reproduction affects considerably but the factors that place them on the list of animals at risk prevent them from having a long life. The exception to this are those animals that are in the care of organizations.
The white shark, in addition to being kept alone and not in litters, is distributed in many places in the world, although this does not allow the exact number of specimens to be known, it does not prevent it from being estimated that its population is a little reduced. It has been concluded in numerous studies that this species does not have an accelerated or at least stable reproductive rate, but it is almost scarce, they take a long time to mature sexually and in addition to that they are captured by humans for sport.
Sport or economic fishing is something that has not stopped increasing, even more so since the white shark has had a presence in cinematographic works, it was not an advantage for them to be seen by so many humans on the big screen and with so many effects. Since 1990 the white shark was considered an insufficiently known species, less than a decade later it was considered vulnerable, today it is considered a threatened species on the list of animals in danger of extinction in many countries.
This entry is another opportunity to emphasize the importance of conservation measures not only for this but for all species that are in danger of extinction, they are in that situation not due to natural factors or due to issues of their own species but due to human activities. mainly. A species that does not reproduce quickly can survive for many years longer than it lives when faced with fishing or factors such as pollution of the seas.
Likewise, although two decades have passed since it was considered a vulnerable species, there has been no reduction in fishing activities for this species. It is prohibited in some places and the movement of these animals too, but there are really not many countries that have regulated any measure to conserve the lives of these animals, although in California, South Africa, Israel, South Australia, Tasmania, Queensland and the Republic of Maldives is a protected species.
These animals, in addition to that, cannot be kept in captivity, in San Francisco a female specimen of this species was kept for three days in 1980, it was not kept longer because it had stopped eating and caused injuries with the walls.
It is presumed that she was trying to escape but what was discovered later was that she was attracted and perhaps disoriented at certain times by the electric field that the wall had, which was really minimal but she could feel it. After that she was released.
attacks on humans
Shark attacks on humans are not really as frequent as they have been shown in film fiction, white sharks are not as aggressive as tiger sharks or bull sharks. Clearly for people who do not have a knowledge beyond the basics that allows them to differentiate one species from another, it is possible that they get confused with them. The bull shark has a record of more attacks on people than the white shark.
Even so, there are species that are much more dangerous to humans than sharks in general, for example crocodiles or sea snakes, it is part of the Characteristics of crocodiles attacking people who are close to them, the reasons are a topic that does not correspond to that entry, the point is that the deaths recorded by shark attacks are lower than those of other marine species, not to mention those of land animals.
Less than 40 shark attacks have been recorded in the Mediterranean in the last two centuries, in South Africa (a country where many more specimens of this species are found than in other countries) less than forty attacks of this species have been recorded, something significant if compares to bull shark attacks in those same waters (89 total as of 1940). The curious thing about all this is that the attacks are not characterized by giving humans several bites, but only one.
Based on the latter, it follows that the reason for the attacks may be protection in the first place, since they place human beings in a position in which they are a threat due to their activity (fishing, for example). Another reason may be the fear of something unknown (such as a ship or a human) that can confuse them and want to try what it is. Finally, it may happen that there is another confusion in the shark and it believes that the person is a habitual prey (by biting once they already see that it is not).
The reason for the low mortality rate caused by white sharks is that humans are not potential prey for white sharks, if human meat were as digestible, nutritious and delicious for them as that of whales or sharks. seals the figures would be completely different.
The fact that the danger of an attack happening is always possible is not ruled out, this is also influenced by the age of the shark, since the older specimens have a more aggressive and dangerous behavior. In any case, it is possible to avoid an attack by this species if certain chemicals are used to repel them, in addition to that the electric fields disorient them, as happened with the Sandy shark in San Francisco.