ANATOMY
The harmless Whale Shark holds the title of largest fish, with the record being a 59 footer captured in Thailand in 1919.
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| Pixibay |
The smallest shark in the world is the dwarf lantern shark, which is about 8 inches long.
Sharks do not have a single bone in their bodies. Instead they have a skeleton made up of cartilage which is the same type of tough, flexible tissue that makes up human ears and noses.
A shark is the only fish that can blink with both eyes.
Sharks are the only fish that can’t swim backwards. If you pull a shark backward by the tail, it will die.
The skin of a female shark is much thicker than that of a male because males bite females during mating.
The thresher shark was named for its thresher-like tail, which can be as long as its entire body. It uses its tail as a weapon to stun prey.
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| Small purple colored thresher caught at Pacifica Pier, California. By Paul E Ester |
A great white shark's liver can weigh up to be 24 percent of its body weight.
The great white shark is the only shark that can lift its head above the water to look for prey.
The great white has several rows of sharp, serrated teeth that can number into the thousands. As teeth fall out, they are rapidly replaced by those in the row behind them.
SENSES
A Shark can sense a drop of blood from 2.5 miles away and can detect one part of blood in"100 million" parts of water (i.e 1:100000000).
Sharks have outstanding hearing. They can hear a fish thrashing in the water from as far as 500 metres away.
Sharks can see up to 10 times better than humans in clear water.
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| Grey reef shark. The original author is Fbattail |
40% of a shark's brain is dedicated to its sense of smell.
Sharks smell in "stereo," meaning they can detect the tiny delays in the time it takes for a scent to reach one nostril compared to the other and use it to determine the direction from where the scent is coming. This helps them in tracking their prey.
Most species of sharks do not produce sounds. The majority of sharks rely on their other senses, particularly their exceptional sense of smell and electroreception, to navigate and locate prey. They do not possess vocal cords or a specialized organ for producing sound like some other animals do.
BEHAVIOR
A pup (baby shark) is born ready to take care of itself. The mother shark leaves the pup to fend for itself and the pup usually makes a fast getaway before the mother tries to eat it!
The mating and birth of whale sharks are mysteries. Neither has ever been observed.
A Great White Shark can fast for as long as three months after a big meal.
Every winter, great white sharks swim for 40 days to meet up between Mexico and Hawaii, and nobody knows why.
When a shark is flipped on its back it enters a state of paralysis that lasts for up to fifteen minutes. The phenomenon is known as "Tonic Immobility." In some cases orcas have been seen maneuvering a shark upside down to induce this paralyzed state.
An Orca killed a Great White Shark near California’s Farallon Islands in 2000. The smell of the dead shark's carcass caused all nearby great whites to vanish. A great white with a satellite tag in the area was seen to immediately dive to a depth of 500 meters and then swam to Hawaii.
RELATIONSHIP WITH HUMANS
In 2004, California’s Monterey Bay Aquarium became the first to keep a great white shark captive for longer than 16 days — 198 days in all. The female — which was accidentally caught in fishing nets — was kept in a 1.2 million-gallon tank before being released after she attacked other sharks in the exhibit.
Between 50 and 70 people are attacked by sharks every year. On average, five people die of a shark attack per annum.
93% of shark attacks between 1580 and 2010 worldwide were on men.
The world’s most deadly shark is the great white, responsible for 251 of the 1,860 confirmed unprovoked attacks on humans in the 20th century.
Great white sharks don't like the taste of humans as they are bony and low in fat and protein, unlike they're preferred food: seals. They often attack humans only because of low visibility.
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| Great white shark By Brocken Inaglory |
It is estimated that 100 million sharks are killed by humans every year. Many of these were driven by the demand for shark fin soup by Chinese consumers. Usually only the fins are taken, while the rest of the shark is discarded, generally into the sea.
In recent years, 85% of Chinese consumers have given up shark fin soup, largely as a result of campaigning by ex-NBA player Yao Ming.
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| Sharks fin soup By Arthur Hungry - From Arthur Hungry |
For every human killed by a shark, humans kill two million sharks.
If you are attacked, punch at the shark's eyes, snout and gills (on the sides of the head, ahead of the pectoral fins). Play dead and the shark will think you are a free lunch.
HABITAT
Sharks generally do not live in freshwater although there are a few known exceptions, such as the bull shark and the river shark, which can survive and be found in both seawater and freshwater.
Bull sharks have been known to travel up the Mississippi River as far as Alton, Illinois.
Scientists discovered sharks that are living in an active underwater volcano - the Pacific Ocean’s violent Kavachi volcano, which lies 20 miles off the coast of the Solomon Islands. Divers cannot investigate because they would get burns from the acidity and heat.
St Helena is the only place on this planet where the mating of whale sharks has been seen by humans.
Great white sharks rarely survive in captivity. Experts suspect being surrounded by glass might either confuse or overload the shark's electroreception system, which is used to sense the electrical signals given off by fish in the open ocean, not necessarily inside a glass box.
LIFE HISTORY
The Greenland shark is currently believed to be the longest-lived vertebrate species on Earth. A recent examination of 28 specimens in one study determined by radiocarbon dating that the oldest of the animals that they sampled had lived for about 392 ± 120 years (a minimum of 272 years and a maximum of 512 years). The authors further concluded that the species reaches maturity at about 150 years of age.
Scientists believe female Greenland sharks don't reach sexual maturity until they are 156 years old.
Source Radio Times
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