Sharks: they rule 70 percent of the world | Photo: Elias Levy/Creative Commons

Sharks are one of the oldest living species on planet earth. They've survived the most severe mass extinction events, and they rule 70 percent of the world.

Ready to learn things you didn't know about sharks? You will be amazed by how special sharks really are. Sharks are fast and intelligent, and they can only fear humans. Yes, we are their only predators.

But their body is a complete underwater machine. Their smell, sight, hearing, mouth, skin, electroreception and lateral line is a complex system built to survive and hunt in multiple environments.

In the past, sharks were known as "sea dogs." Today, sharks are the masters of the water world. Respect them, and learn everything you need to know about sharks:

1. The largest shark ever found was a whale shark measuring 41.50 feet;
2. The smallest shark is the dwarf lantern shark; it measures 6 inches;
3. The most common shark is the ocean whitetip;
4. The fastest shark is the short-fin mako shark, and it can swim up to 65 mph;
5. Sharks detect a blood drop in an Olympic pool;
6. A shark bite generates up to 40,000 pounds of pressure per square inch;
7. The great white shark eats 22 times more than an average human;
8. Sharks are not mammals; sharks are fishes;
9. There are roughly 500 species of sharks;
10. Sharks are between 425 and 455 million years old;
11. Sharks are older than dinosaurs;
12. The oldest shark teeth were found in Europe;
13. Sharks were in the 5 percent of the species that survived five major mass extinction events;
14. Sharks use their electro-sensors (Ampullae of Lorenzini) to locate prey and navigate the oceans;
15. Sharks can open their mouth to nearly 180 degrees;
16. Sharks have rows of teeth;
17. A shark may produce roughly 6,000 teeth each year;
18. Sharks don't have bones, only cartilage;
19. Bull sharks can live in both salt and fresh water;
20. Salmon sharks regulate their body temperature to live in the Alaskan waters;
21. Shark mating can involve biting;
22. Reproductive cycles for sharks can last two years;
23. Some female sharks can store sperm for up to a year;
24. Shark sight works similarly to that of humans;
25. Sharks see in dark or murky water up to ten times greater than humans in clear water;
26. Sharks get cancer;
27. Half the world's shark fin trade in goes through Hong Kong;
28. Commercial fishing kills 100 million sharks each year;
29. Shark fin soup is a Chinese specialty since the Ming Dynasty;
30. It hasn't been scientifically proven that shark liver oil or its components are effective against cancer;
31. Only 10 out of 500 species of sharks have been involved in incidents with humans;
32. Sharks hunt in the evening and night;
33. The average life span of most shark species is 20 years;
34. The spiny dogfish shark can live more than 100 years;
35. Sharks sleep with their eyes open;
36. Sharks live in the waters from 7,000 feet to 10,000 feet;
37. Shark have a rough skin;
38. Blue sharks like cooler waters;
39. Some shark species drown if they stop moving;
40. Your odds of getting attacked and killed by a shark are 1 in 3,750,000;
41. There's intrauterine cannibalism in the shark world;
42. Sharks prefer to hunt solo;
43. Galeophobia is the excessive fear of sharks;
44. Sharks have a 360-degree vision;
45. Sharks only have inner ears;
46. Sharks have seven senses;
47. Great white sharks jump 10 feet in the air;
48. Sharks can be found in all oceans of the world;
49. The majority of sharks are ovoviviparous;
50. Sharks are part of the Hawaiian mythology;
51. The great white shark is protected in South Africa since 1991;

Take a look at the most shark-infested waters in the world. Learn how to survive a shark attack.