There are about 350 different types of sharks, but researchers think there are other sharks that haven’t been discovered yet!
Most sharks live for about 25 years, while some of them can live to be a 100 years too.
More people are killed by bee stings than by shark attacks. Sharks are said to attack more women than men. The reason is still a mystery.
The Basking shark is the second largest fish known to humankind; it is as long as 40 feet.
The hammerhead shark is named for unusual shape of their heads. Their wide heads help them to steer through the water.
The largest shark and, indeed, the largest fish known (living or fossil) is the whale shark (Rhincodon typus). It has been measured to be over 12 m (about 40 ft.), and there are reports of 18 m (about 60 ft) individuals. Weights are difficult to estimate, but an 11.5 m specimen weighed over 12,000 kg (26,500 lbs, or over 13 tons). The whale sharks are gentle giants with very large mouths and thousands of incredible small teeth. They are filter feeders, eating small animals living in the sea by swallowing large volumes of water and straining it out through the gills. These massive animals live in tropical and warm temperate seas around the world, except for the Mediterranean. They pose no danger to man.
The Blue shark had been known to migrate from 1,200-1,700 miles (2000-3000 km) in a seasonal journey from New York state in the USA to Brazil.
Most sharks swim at 20-40 miles per hour while the Mayo shark is said to swim up to 60 miles per hour.
The four most dangerous sharks are the great white, bull, tiger, and oceanic whitetip. These are all large (up to about 6 m, almost 20 ft, and more than 2000 kg, over 4,800 lbs) and eat prey that is similar in size to humans. All but the last species frequent shallow coastal waters where most swimmers are to be found. Off the coast of California, many shark attacks have been attributed to cases of mistaken identity where surfers, lying on their boards, have a silhouette that is remarkabley like that of a sea lion, a common food item of great white sharks. However, shark attacks are relatively rare and fewer than 30% are fatal; fewer than 100 attacks are reported per year worldwide. Considering that a tally of 50 motor vehicle accident fatalities in a month in Wisconsin is considered low, sharks pose a potentially gruesome but rather insignificant threat to humans. In fact, considering that about 100,000 sharks are killed by man each year, threatening many species with extinction, sharks are in far more danger from us than we are from them.
Sharks can actually detect the very weak electrical fields generated by the muscular activity of other creatures. This remarkable 6th sense, called electroreception, is made possible by the “ampullae of Lorenzini,” a sophisticated set of sense organs located on the skin.
Electroreception helps sharks identify and track possible prey, and is so sensitive that it even helps sharks position their mouth and head when attacking.
The liver of a basking shark can weigh over 2000 lbs. (900 kgs.)! The basking shark is the second biggest fish in the sea, and like many sharks relies on its liver for some of its buoyancy. The liver of a basking shark can be especially large, accounting for up to 25% of its total body weight! Some scientists speculate that the basking shark’s liver may also act as a winter food reserve.
Basking sharks over 35 feet (12 meters) have been measured, and reports of basking sharks close to 50 feet (17 meters) have been received. These huge animals, some of which weigh more than 10,000 lbs. (4500 kgs.), frequently make spectacular leaps clear out of the water.
Unlike most fish, sharks have eyelids! These eyelids are different from the eyelids of humans and other mammals, closing by unrolling from the bottom of the eye rather than the top. Sharks’ eyelids help protect their eyes while attacking prey.
Just like high-tech “starlight” night-vision goggles, the eyes of sharks multiply the available light to allow them to see in almost total darkness!
Sharks have a very sophisticated eye structure that is not well understood by scientists, but their ability to see in the dark is attributed to a kind of mirror inside the eye. This mirror enhances low-light vision by reflecting light through the retina twice.
This “twilight vision” allows sharks to see reasonably well in nearly complete darkness, and very well with just starlight.
Sharks’ ears are so finely tuned that they can detect a struggling fish up to 2 km away! Sharks’ acute sense of hearing is the most important method they use to find their prey.
Despite their remarkable hearing abilities, sharks (like many fish) do not have external ears. Instead, they have tiny passages that carry the sound waves to inner ears.