65 facts about sharks that prove 65 times that they are unusual fish

Facts about sharks that should be in school biology textbooks.

If at least a couple of these facts were included in biology lessons at school – at least about sharks that can live in fresh water, at least about the fact that sharks use the Earth’s magnetic field for navigation and sense electric fields created by the respiratory organs and heart of other animals, at least about mako sharks that can swim at a speed of 74 km/h and jump out of the water up to 6 meters high – it would be much more interesting to look into a school textbook.

Once again, we at the Travel Club could not help but be surprised when we learned about these unusual and fascinating facts about sharks. And now it’s time for you to be surprised too.

1. During its life, a shark can lose and regrow up to 35,000 teeth. They are constantly changing.
   Unlike humans, who grow 20 baby teeth, which are replaced by 32 adult teeth, the number of teeth that a shark changes in its life will shock you…
   On average, sharks have from 50 to 300 teeth. A basking shark, for example, has 300 backward-curved teeth, each of which is equipped with two additional needle-like teeth that tightly fix the caught prey. Sharks can lose dozens of teeth every month, and over the course of their lives, they can lose between 25,000 and 35,000 teeth, which are constantly replaced by new ones.
2. Whale sharks can live up to 100 years.
3. Sharks are color blind.
   Studies show that sharks most likely see the underwater world in black and white.
4. Sharks have existed for over 400 million years.
5. Sharks have no bones in their skeletons. They are made of elastic tissue called cartilage.
6. There are about 500 different species of sharks.
7. Sharks have electroreception, an electroreceptor apparatus that allows marine predators to detect prey by the electric fields generated by the victim’s respiratory muscles and heart.
   This is possible thanks to the connective tissue capsules with tubes that extend from them and open to the skin surface. According to research, sharks can sense the electrical signals of other animals, even if the electric field strength of a living organism is only 0.01 μV/cm.
8. Sharks are also extremely sensitive to pressure changes in the water. They can notice the slightest changes thanks to their special cells with tiny hairs in them.
9. Great white sharks weigh an average of 680-1100 kg. But there are individuals that weigh 1800-3000 kg.
   In 1945, a shark was caught in Cuban waters that may have weighed 3324 kg. However, this has not yet been officially confirmed by science.
10. Whale sharks are about the size of an American school bus.
    Typical individuals are 12.5 meters long. But occasionally, sharks as long as 18 meters and even 20 meters can be found.
11. Tiger sharks are very voracious and indiscriminate in their food – they are ready to eat anything. That is why they are the most dangerous for humans.
12. Food can stay in the shark’s stomach for up to several months.
13. Shark skin is tough and thick because it consists of a protein called collagen. For example, the skin of a whale shark can be up to 10 centimeters thick!
14. The pregnancy of a female shark can last from 5 months to 2 years, depending on its species.
    The spotted spiny shark (catran) has a gestation period of 2 years.
15. If the shark embryo develops teeth, it will participate in intrauterine cannibalism, i.e. eat its siblings inside the uterus.
16. Female sharks are often larger than male sharks.
17. The bull shark (gray bull shark) is able to survive in fresh water.
18. A blue shark can give birth to up to 135 cubs in a single pregnancy.
19. A fox shark’s tail can grow to about half its body length. The predator uses its long tail fin as a whip, whipping its prey into a flock and stunning it.
20. Sharks have very developed hearing. They can hear low-frequency sounds: mainly 100-2500 Hz, which allows them to hear at a distance of up to 400 meters.
21. The eponymous catshark can use its fins as legs to walk when the water level is too low to swim without problems.
22. Young white sharks spend several years in a shallow place with plenty of sun and food, where they grow and learn to hunt.
23. The probability of being attacked by a shark is 1 in 11,500,000, and the chance of dying is 1 in 264,100,000.
24. Sharks that live in the deep ocean can glow due to bioluminescence.
25. Most female sharks have much thicker skin than males because they often bite during mating.
26. The Greenland polar shark is the slowest fish in history, but reindeer, polar bears, and extremely fast seals have been found in its stomach.
    Greenlandic polar sharks are one of the slowest fish in the world. Their average speed is 1.6 km/h, and the maximum speed is 2.7 km, which is half the maximum speed of seals. By the way, this has long bothered scientists because they could not understand why seals are often found in the stomachs of these sharks. After all, with such a slow speed in the water, it is impossible for them to catch seals. Experts believe that perhaps Greenlandic polar sharks are waiting for seals sleeping on ice floes.
27. Hammerhead shark pups have soft lateral outgrowths of the head.
28. Sharks can be introverted or extroverted.
    One study showed that sharks have individual personality types. The more social sharks team up and prefer to socialize with a group. But there are also loners who lead an independent lifestyle, hunting and swimming alone.
29. Whale sharks can give birth to several hundred cubs in one litter.
30. Sharks are one of the slowest reproducing fish species.
31. The white shark Lydia crossed the Atlantic Ocean: scientists followed her. The second such shark in history was Nukumi.
32. Sharks respond to a special sound made by injured fish, which allows them to find easy prey.
33. The shark’s teeth are covered with fluoride, so to a certain extent they have a built-in dental protection that preserves them like toothpaste.
34. Nurse sharks are very lazy. They spend most of their time resting on the seabed and like to lie close to each other (or even on top of each other).
35. Great white sharks, which live off the coast of Seal Island in South Africa, jump out of the water 3 meters to attack seals unexpectedly.
36. White sharks have three rows of teeth. And there are more than 300 of them.
37. The skin of sharks is covered not with scales but with dermal teeth.
    Skin denticles are much more like teeth than ordinary fish scales. The dense plates of scales are hidden under the skin, with only sharp, small spines coming out. These jagged scales allow them to move quickly through the water without collecting shells and algae.
38. Great white sharks can detect one drop of blood in 90-100 liters of water. They can also sense small amounts of blood in the water at a distance of up to 5 kilometers.
39. Lantern sharks can glow in the dark.
40. Some female sharks can reproduce without any contact with a male, which is known as parthenogenesis.
41. Despite its enormous, threatening size, the whale shark is the safest for humans – it feeds on tiny plankton.
42. The goblin shark lives along the outer continental shelves and underwater mountain ranges in areas that are too deep for human exploration.
43. A bite from a white shark can cause a pressure of 3 tons per 1 square centimeter.
44. A giant shark (or also called a gigantic shark), which feeds on plankton, like a whale shark, can grow up to 15 meters in length.
45. In 1978, archaeologists discovered the remains of shark bodies under the ruins of the Great Aztec Temple.
46. Great white sharks eat about 11 tons of food every year. For comparison, an adult human eats about half a ton.
47. Mako sharks are considered the most agile. The fish can reach an average speed of 74 km/h.
    They can also jump out of the water to a height of up to 6 meters and even make a series of jumps. But the main advantage of this type of shark is its ability to accelerate quickly. For example, makos can cover 30 meters in 2 seconds, reaching a speed of 110 km/h.
48. A great white shark “rolls” its eyes to protect them during an attack. Many shark species have a movable transparent flashing membrane that covers and protects their eyes when they attack and eat.
49. Sharks are opportunistic predators, they eat whether they are hungry or not.
50. Sharks have an almost 360-degree field of vision, and they have only two blind spots: one in front of their snout and the other right behind their head.
51. Sea angels are called sand devils because they bury themselves on the ocean floor and wait for unsuspecting fish, which, if they swim by, they will immediately attack.
52. The pelagic great white shark was discovered only on November 15, 1976. Before that, scientists did not know the species.
53. Humans kill about 100 million sharks every year in the world, or 11,000 every hour.
54. Tiger sharks have such strong jaws and sharp teeth that they can bite through the shell of a sea turtle.
55. Megalodon, which lived 16-2 million years ago, could grow up to 15 meters long, weigh up to 47 tons, and had the strongest bite of any living creature.
56. According to the latest data, only 20 of the known shark species attack humans.
    Most often, white, tiger, bluntnose and longfin sharks attack for no reason.
57. The dwarf shark is one of the smallest in the world. Its length reaches only 26.5 cm.
58. Sharks have a really good memory.
59. Humans can survive without food for about 30 days before their internal systems begin to break down. Sharks go hungry for about 6 weeks every year. In addition, the record for shark fasting is over 15 months.
60. Sharks do not have vocal cords. They communicate through body language, such as bumping or shaking their heads, or even by arching their backs.
61. Unlike common fish, sharks do not have a swim bladder to keep them afloat – instead, sharks have a large, oil-filled liver.
    A shark’s liver can make up an incredible 25% of its total body weight. This huge organ is filled with oil that contains the low-density hydrocarbon squalene, which makes it lighter than water and helps the shark stay buoyant. Just as the air bladder does in common fish.
62. In the 1980s, the shark’s maneuverability and buoyancy were compared with the capabilities of submarines to improve the performance of underwater vehicles. It turned out that a shark needed six times less propulsion to swim successfully underwater. This discovery led to remarkable new experiments with racing yachts, submarines, and bathing suits, resulting in the invention of coating technology that reduces friction with water.
63. Sharks are more likely to attack men.
    No one knows why sharks prefer to attack men. In fact, almost 90% of shark attacks have occurred to men.
64. When it’s time to give birth, a female shark loses her appetite so that she won’t be tempted to eat her own young.
65. Sharks can use the Earth’s magnetic field with special senses that act as a compass to navigate the oceans.