100 Facts About Sharks

With over 465 known species and an evolutionary history spanning 420 million years, the shark is one of the most varied and interesting species of fish in the oceans. In this article we’ve collated 10 facts from 10 different subjects about this complex, fascinating, and often misunderstood animal.


Predation and Feeding

1. Some sharks can detect blood at one part per million of water

sharks-detect-bloodA shark’s nostrils are located on the under-side of its snout and are used solely for smelling and not for breathing.

2. Whitetip Reef Sharks hunt in groups

Whitetip-group
While most sharks are thought to be solo hunters, the Whitetip Reef Shark hunts at night and in packs.

3. An average of 16 fatal shark attacks occur every year in the US

great-white-attackYou are more likely to be killed by a champagne cork, falling coconut, or even being trampled by a cow than you are by a shark attack.

4. Some sharks can hear their prey from several miles away

shark-hearingOpenings on the side of their head lead to the inner-ear and enable the shark to hear extremely low frequency sounds from a great distance

5. Shark taste buds aren’t located on their tongues

shark-tastebudsUnlike humans and many other animals, shark taste buds are found around the entirety of their mouths.

6. Sharks can’t tell the difference between a seal and a surfboard

shark-surfboardDespite having relatively good eyesight for a fish, sharks can’t always tell the difference between different types of prey, meaning surfers often get attacked by mistake.

7. Many sharks have eyelids

shark-eyelidsDespite their un-blinking, un-nerving reputation, many sharks have protective coverings that deploy instantly when attacking prey to protect their own eyesight.

8. Sharks can detect vibrations in water

shark-vibrationsKnown as a ‘lateral line’  sharks have an internal sense that enables them detect vibrations in the water, helping them locate their prey.

9. Sharks can detect electricity in water

sharks-detect-electricityBy using organs known as the ‘ampullae of Lorenzini’, sharks can easily detect the electricity omitted by all living creatures as they move through the water.

10. Sharks can survive for weeks without eating

sharks-survive-without-food   Many sharks will eat huge meals at one time and are able to survive for weeks off oil stored in their liver.


Reef Sharks

11. Reef sharks rarely venture more than 80 metres deep

Ree-shark-coral Reef sharks love subtropical water and can often be found in the shallows of Pacific and Indian Ocean coral reefs.

12. Reef sharks herd their prey

reef-shark-herding Reef sharks have a varied diet ranging from squid and shellfish to different types of reef fish. They often herd their prey against reef faces so they are easier to catch.

13. Reef sharks have a gestation period of 12 months

pregnant-reef-shark Reef sharks are viviparous, which means the offspring develops inside the mother.

14. Reef sharks are more dangerous to reef divers than any other shark

reef-shark-humans Grey and silvertip reef sharks are considered the most dangerous to divers, although the majority of attacks on humans are non-fatal.

15. Reef sharks can be found in 40% of South African fishing hauls

shark-in-net Despite the fishing or hunting of reef sharks being illegal, their population is still being drastically affected by the industry.

16. Caribbean reef sharks are able to evert their own stomachs

reef-shark-stomach Everting their stomach helps to purge and cleanse themselves of any parasite or indigestible particles.

17. The grey reef shark often lives in schools of more than 100

Grey-reef-sharks-school The grey reef is a very social species and social hierarchy and dominance has been observed in many schools

18. Grey reef sharks have an excellent sense of smell

grey-reef-shark-smell Grey reef sharks have a better sense of smell than most fish and can track their prey from great distances.

19. The World Wildlife Fund classifies reef sharks as one of the most important species on the planet

reef-shark-wwf Reef sharks are at the top of the food chain in reef environments, making them the apex predator in a very significant ecosystem.

20. Humans are the number one predator of the reef shark

reef-shark-hook Reef sharks are the victim of intensive fishing by humans due to their desirability in Asia for use in delicacies such as shark fin soup.


 Whale Sharks

21. The whale shark is the largest species of fish in the world

whale-shark-size The largest confirmed whale shark was 12.65m in length and weighed approximately 21.5 metric tons.

22. The spots surrounding a whale shark’s gills are as individual as a human’s finger print

whale-shark-spots The individuality of the marking surrounding the whale shark’s gills helps scientists identify individual sharks.

23. A whale shark’s mouth can be over a metre wide

whale-shark-mouth The vast size of a whale shark’s mouth enables it to feed more efficiently

24. Whale sharks are filter feeders

whale-shark-feeding Along with the basking and megamouth sharks, the whale shark is one of only three filter feeding sharks.

25. Whale sharks live to be over 70 years old

whale-shark-age Whale sharks reach maturity relatively late and don’t produce offspring until they reach their 40s

26. The wild whale shark population is decreasing

whale-shark-population Due to their long lives and relatively few offspring, the whale shark population is increasingly threatened by loss of habitat, marine pollution, and human trade.

27. Whale sharks pose no threat to humans

whale-shark-human Many divers and researchers have observed whale sharks from a close proximity and have even been permitted to remove parasites and bacteria from the shark’s body.

28. Whale sharks have more than 300 rows of teeth

Whale-Shark-teeth Despite their large number, a whale shark’s teeth are of very little use as a filter feeder.

29. Whale sharks are extremely slow swimmers

whale-shark-swimming A whale shark rarely reaches a speed of more than 3mph and must move its entire body from side to side to gain momentum.

30. The whale shark is revered as a deity in certain aspects of Vietnamese culture

Whale_shark_vietnam In Vietnam, the whale shark is known as Cá Ông, which translates to ‘lord fish’.


Great White Sharks

31. Great white sharks can grow to over 6.4 metres in length

great-white-size Mature great whites often grow to 6.4 metres with some sharks reported to be over 8 metres long and 7,000 lbs in weight.

32. Great white sharks can live to be over 70 years old

great-white-age Its 70+ year lifespan makes the great white one of the longest living cartilaginous fish in the world.

33. The great white is responsible for the largest number of fatal shark attacks on humans

great-white-shark-humans Despite being responsible for the most fatal attacks on humans, the great white isn’t the ferocious man-killer depicted in fiction and actually prefers to prey on many other creatures.

34. Great white sharks can reach speeds of up to 35mph

great-white-speed The great white can reach speeds far in excess of the average shark due to its streamlined body and powerful stature

35. A great white can bite with a force of over 18,000 newtons

A team of scientists measured the bite force of a randomly selected specimen measuring 6.1m in length, meaning that many great great whites could bite with an even greater force.

36. Female great whites dominate the males

great-white-female Great whites live in a dominance hierarchy and separate themselves based on size and sex, with newcomers also being dominated by ‘resident’ sharks.

37. Great whites lift their heads above sea level to spy on their prey

great-white-spyhopping Great whites are one of very few sharks known to engage in this behaviour – known as ‘spy-hopping’.

38. The vast majority of great white attacks occur within two hours of sunrise

great-white-shark-sunrise Great whites are ambush hunters and attack from the depths of the ocean when visibility is poor.

39. Great whites can launch themselves 10 feet above sea level

great-white-breaching When hunting seals, great whites often attack from below with such speed and ferocity that they breach the surface completely.

40. Great whites immediately flee if they smell the carcass of a different great white in the area

great-white-orca A population of about 100 great whites is recorded to have vanished from an area where an orca had killed one of their peers. 


 Basking Sharks

41. The basking shark is the second largest fish in the world

basking-shark-size Basking sharks can grow to lengths of over 35 feet, only the whale shark is larger.

42. Basking sharks are one of only three plankton-eating sharks in the ocean

basking-shark-feeding Along with the whale shark and the megamouth shark, basking sharks feed on plankton via filtering.

43. Basking sharks can filter up to 1,800 tons of water per hour

BASKING SHARKS SEEN OFF THE COAST OF CORNWALL The basking shark is a passive feeder, meaning it filters great amounts of water in order to ingest zooplankton, small fish and invertebrates.

44. Basking sharks have a gestation period of between 2 and 3 years

basking-shark-pregnant The sharks mate in the summer and give birth to a small number of fully developed young.

45. It is estimated that basking sharks live for around 50 years

basking-shark-age Estimates put the lifespan of the basking shark at 50 years, although the exact length is unknown as research is lacking.

46. The number of wild basking sharks is rapidly declining

basking-shark-population Like many sharks, basking sharks are sought after for food and for use in traditional Chinese medicine. It is now a fully protected species in many countries.

47. The Canadian government tried to fully eradicate the basking shark

basking-shark-canada Basking sharks were once considered a nuisance and the Canadian government ran an eradication programme between 1945 and 1970.

48. Basking shark corpses were often confused with sea monsters and mythical beasts

basking-shark-dead In the 1800s several reports described ‘sea serpents’ being washed up on beaches. It is now believed the beasts were in fact the decomposing corpses of basking sharks.

49. Basking sharks can weigh up to 7 tonnes

basking-shark-weight Their immense size, slow speeds and propensity to feed near the surface gave the basking shark its name as it is perceived to be frequently lounging in the sun.

50. Basking sharks travel in gender-specific groups

basking-shark-group Although they often travel alone, basking sharks are social animals and regularly form groups of 3-4, usually segregated by sex.


Habitat and Migration

51. Bull sharks and river sharks are the only two species that can live in both seawater and freshwater

river-shark With the exception of bull and river, all species of shark swim only in saltwater.

52. Some sharks have more complex migration patterns than those of birds

whitetip-shark Social species of shark, such as the whitetip reef shark, travel huge distances around entire ocean basins.

53. Great white sharks migrate across thousands of miles

great-white-migration Great whites aren’t alway associated with migration but one great white was tracked migrating from the Central California coast all the way to warmer waters off Hawaii.

54. Whale sharks can migrate over 5,000 miles to give birth

whale-shark-migration One pregnant female whale shark was tracked migrating 4,800 miles across the Atlantic before her tag came loose

55. Every year thousands of blacktip sharks migrate along the Atlantic coast of Florida

blacktip-migration The migration of blacktip sharks is thought to be the largest annual shark migration in U.S. coastal waters.

56. Shark migration is affected by global warming

Sharks-global-warming Global warming is changing where warmer waters are found and therefore to where sharks annually migrate.

57. Many sharks follow the migratory patterns of their prey

shark-and-seal When a shark’s prey migrates to warmer water to give birth, sharks will follow suit. Great white sharks migrate to areas where elephant seals give birth in order to feed on their pups.

58. Shark species that can generate their own heat have a greater migratory range

shark-body-heat Sharks that can’t generate their own body heat are restricted to warmer migratory patterns.

59. Almost 50% of migratory sharks are considered threatened by the IUCN

shark-migration Migratory sharks are considered at much greater risk of extinction than non-migratory sharks by the International Union for Conservation of Nature.

60. The deepest confirmed report of a shark is a Portuguese dogfish at 3,700 metres

portuguese-dogfish Although most sharks prefer shallower, warmer waters, the Portuguese dogfish inhabits lower continental slopes and abyssal plains.


Mako Sharks

61. The mako shark is the fastest species of shark in the world

mako-shark-speed Mako sharks can swim at 60mph when hunting for food.

62. Mako sharks are popular targets for sport fishermen

mako-shark-fishing Due to their great speed and agility, many fishermen consider mako sharks the ultimate prize.

63. Mako sharks often leap out of the water – but nobody knows why

mako-shark-leap Researchers have several theories as to why mako sharks leap out of the water more than other species but no theory has been proven definitive. One possible reason is they leap high in order to search for food.

64. The name ‘mako’ originates from the Maori language for ‘shark tooth’.

Short-finned Mako Shark, California Many Polynesian cultures were understood to highly value the teeth of the mako shark which is prevalent in high numbers around their coastal waters.

65. The mako shark is one of only four warm-blooded shark species

mako-shark-warm-blood Being endothermic, mako sharks are rarely found in waters colder than 16˚C

66. Mako sharks rarely venture into water deeper than 150 metres

mako-deep-water As a pelagic species, makos are normally found far from land and within 150 metres of the surface.

67. Shortfin mako sharks travel vast distances to seek prey or mates

mako-shark-prey One female mako shark was tagged in 1998 having travelled over 1,725 miles.

68. Mako sharks often feed on other sharks

mako-shark-cannibal Mako sharks have a varied diet, ranging from porpoises and turtles to tuna, mackerel and even other sharks. 

69. Shortfin mako sharks consume 3% of their bodyweight a day

mako-eating Compared to inactive species of shark which consume around 0.6% of their bodyweight a day, mako sharks consume large amounts of food.

70. Mako sharks have a 15 – 18 month gestation period

mako-pregnant Female mako sharks give birth to 4 – 18 young and rest for 18 months before mating again.


 

Hammerhead Sharks

71. Hammerhead sharks swim in schools during the day and hunt solo at night

hammerhead-school Unlike many sharks, hammerheads are solo hunters at night while also being social animals during daylight hours.

72. Hammerhead sharks have 360˚ vision

hammerhead-eyesight The distinctive head shape of a hammerhead shark allows it the see above and below at all times, granting a significant advantage when hunting and defending.

73. Hammerhead sharks are especially adept at sensing electrical fields in the water

hammerhead-electrical-sense The distinctive shape of their head allows for a larger surface area of ampullae of Lorenzini, resulting in better detection of electrical fields than many other fish.

74. Male hammerheads violently bite the female until she agrees to mate

shark-mating Hammerheads mate once a year after partaking in this particularly aggressive ritual.

75. The bonnethead shark is capable of asexual reproduction

bonnethead The female bonnethead’s ovum forms a zygote by bonding with a polar body without the need for a male.

76. The great hammerhead shark often engages in cannibalistic practices

great-hammerhead-shark   The largest species of hammerhead, the great hammerhead, often eats its own young as well as other hammerheads.

77. Hammerhead sharks use their head  as a weapon

hammerhead-fight Hammerheads are known to pin down rays and other prey with their unique heads before killing and eating them.

78. Only 3 of 10 known hammerhead species are particularly dangerous to humans

scalloped-hammerhead Only the scalloped, great, and smooth hammerheads are considered at all dangerous to humans. There have been 33 recorded hammerhead attacks between 2013 and 2015, none of which were fatal.

79. Two hammerhead species are on the IUCN endangered species list

hammerhead-conservation The great and the scalloped hammerhead are listed as endangered by the World Conservation Union, mostly due to over-fishing.

80. In Native Hawaiian culture, hammerhead sharks were considered gods of the sea, protectors of natives and cleansers of the ocean

hammerhead-hawaii Known as ‘aimakua’, hammerhead sharks were greatly respected in Native Hawaiian culture and were thought to protect the islanders from man-eating sharks.


Tiger Sharks

81. The tiger shark is a mostly nocturnal hunter

tiger-shark-hunting Tiger sharks hunt at night in solo missions for a wide variety of prey

82. The tiger shark is commonly known as a ‘garbage eater’ due to often eating inedible and man-made objects

tiger-shark-eating The inedible objects swallowed by tiger sharks often linger in their stomachs, unable to be broken down and digested.

83. The tiger shark has the widest dietry spectrum of all sharks

tiger-shark-diet Tiger shark prey ranges from crustaceans, fish and birds, to dolphins and sea snakes, among others.

84. The tiger shark is the largest of the requiem family of sharks

tiger-shark-size Requiem sharks are migratory, live-bearing sharks found in warm seas.

85. Tiger sharks are a nomadic species that follow warm currents

tiger-shark-migrate Tiger sharks generally stay close to the equator throughout the year but have been spotted as far south as New Zealand and as far north as Japan.

86. Tiger sharks are regularly reported at depths thought to be too shallow for a fish its size

tiger-shark-shallows The average tiger shark is reported at a depth of around 350 metres but they are regularly spotted in coastal waters at 6 – 12 metres.

87. Female tiger sharks are larger than their male counterparts

female tiger shark Like many spark species of shark, female tiger sharks are the larger of the two sexes. One female specimen was measured at 5.5 metres in length.

88. The tiger shark’s stripes and spots fade with age

tiger-shark-markings The marking from which the tiger shark’s name is derived are only visible on young sharks and fade dramatically as the shark matures.

89. Female tiger sharks mate once every three years

tiger-shark-mating Tiger sharks in the northern hemisphere generally mate in November, December, or January and their young take 16 months to develop in the mother’s body.

90. The tiger shark is responsible for a large percentage of fatal shark attacks on humans

tiger-and-human Although shark attacks on humans are very rare, the tiger shark’s propensity to dwell in reefs, harbours and canals means it is often involved when attacks do happen.


Breeding and Conservation

91. An estimated 73 million sharks are harvested annually just for their fins

shark-fins Shark fin soup and traditional Chinese medicines have increased the demand for shark fins and the practice is largely unregulated.

92. Shark fins are one of the most expensive sea food products in the world

shark-fin-soup Shark fins can fetch up to $300/lb in many Asian markets and the harvesting of fins is a lucrative business which is dramatically harming the levels of shark in the oceans.

93. The Shark Conservation Act of 2010 made shark finning illegal in American waters

sharks-usa The Shark Conservation Act protects sharks from fishermen in American waters but much of the world’s oceans remain unregulated.

94. A quarter of the world’s sharks and rays are threatened by extinction

shark-extinction According to the IUCN Red List of Threatened Species, approximately 1/4 of the world’s shark species are threatened with extinction mostly because of over-fishing.

95. Since 2013, all EU vessels are required to land sharks with their fins naturally attached

shark-europe Recent changes in regulation have made great strides to reduce the damage done by over-fishing and finning in the EU and North America

96. The value of a single live reef shark is more than $200,000

Whitetip_reef_shark Due to ecotourism, the value of live sharks is far greater than dead ones, meaning shark conservation will hopefully become integral to fishermen and local communities around the world.

97. For every fatal attack on humans, an estimated 10 million sharks are killed by man.

sharks-killed Over-fishing, finning, destruction of habitat and a culture of fear have all contributed to the dwindling global shark population.

98. Male sharks have two reproductive structures called claspers which they use to impregnate females

shark-mating While the anatomy of sharks is well documented, the act of mating is very rarely seen by humans.

99. Whale sharks reach sexual maturity at 30 years old

whale-shark Due to its relatively late age of maturity, the whale shark is particularly prone to the dangers of over-fishing and environmental damage.

100. A decreased shark population negatively affects the entire oceanic ecosystem

shark-ecosystem Many sharks are the apex-predator in their habitat and their absence harms all the surrounding marine life, from their direct prey all the way down to marine flora. 

Lee is a freelance writer with a keen interest in history and science.