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136 shark facts, all checked

Every fact on this site, in one place, each linked to its source. Our build checks each one against the source text; see the sources page.

Jump to: What is a shark? | Anatomy | Senses | Eggs and pups | Giants | Hunters | Reef and seabed | The deep | Isle of Man and British waters | Threats and conservation | Bites

What is a shark?

  1. 1 Sharks are cartilaginous fish: their skeletons are made of cartilage, not bone, and they have five to seven gill slits on each side of the head. Wikipedia
  2. 2 There are more than 500 species of shark. Wikipedia
  3. 3 Shark-like fish first appeared in the Devonian Period, between 419 and 359 million years ago. Wikipedia
  4. 4 The earliest confirmed modern sharks are known from the Early Jurassic, around 200 million years ago. Wikipedia
  5. 5 Sharks have lived in our oceans for over 400 million years, well before the dinosaurs. Shark Trust
  6. 6 Most sharks don’t live in fresh water. The bull shark and the river sharks are exceptions, and the Ganges shark lives only in fresh water. Wikipedia
  7. 7 Sharks are found in all seas and are common down to depths of about 2,000 metres. Wikipedia

Anatomy

  1. 8 Shark skin is covered in placoid scales, also called dermal denticles, which protect the skin and help water flow past. Wikipedia
  2. 9 Sharks have numerous sets of replaceable teeth. Wikipedia
  3. 10 Sharks shed their teeth all the time; some ground sharks shed about 35,000 teeth in a lifetime. Wikipedia
  4. 11 Sharks are known to lose at least one tooth a week. Wikipedia
  5. 12 Unlike bony fish, sharks have no gas-filled swim bladder. They stay buoyant with a big, oily liver and cartilage that is about half as dense as bone. Wikipedia
  6. 13 A shark’s liver can make up to 30% of its body mass. Wikipedia
  7. 14 Unlike other fish, sharks don’t have a cover over their gill slits; the slits sit in a row behind the head. Wikipedia
  8. 15 A modified gill slit called a spiracle sits just behind the eye and helps some sharks take in water. Wikipedia
  9. 16 Not all sharks have to keep swimming to breathe, but they all need water flowing over their gills. Wikipedia
  10. 17 Sand tiger sharks gulp air at the surface and hold it in their stomachs, using it like a swim bladder. Wikipedia
  11. 18 Great whites are partly warm-blooded, which helps them stay active in cold water. Wikipedia
  12. 19 A heat-exchange system keeps a mako 4 to 5.5 °C warmer than the water around it. Wikipedia

Senses

  1. 20 Sharks have hundreds to thousands of electroreceptors called ampullae of Lorenzini, which detect the electric fields given off by living things. Wikipedia
  2. 21 Electroreception helps sharks, particularly hammerheads, find prey. Wikipedia
  3. 22 Each ampulla is a gel-filled canal that opens to the surface through a pore in the skin. Wikipedia
  4. 23 The organs are named after the Italian physician Stefano Lorenzini, who described them in detail in 1679, without knowing what they were for. Wikipedia
  5. 24 Like other fish, sharks have a lateral line, a row of sense organs that detect movement, vibration and pressure changes in the water. Wikipedia
  6. 25 Behind the retina, many sharks have a reflective layer called the tapetum lucidum, which bounces light back and helps them see in dark water. Wikipedia
  7. 26 In one study of 17 shark species, 10 had no cone cells at all, which means good night vision but no colour vision. Wikipedia
  8. 27 Sharks have a keen sense of smell. Wikipedia

Eggs and pups

  1. 28 Sharks have their young in three ways: laying eggs, keeping the eggs inside until they hatch, or growing the young without a traditional egg at all. The last two both end in live birth. Wikipedia
  2. 29 Most sharks are ovoviviparous: the eggs hatch inside the mother and the pups are born live. Wikipedia
  3. 30 Egg-laying sharks include the horn shark, catsharks, the Port Jackson shark and the swellshark. Wikipedia
  4. 31 An egg case, often called a mermaid’s purse, is the casing around the eggs of egg-laying sharks, skates and chimaeras. Wikipedia
  5. 32 Most egg cases are roughly rectangular, with a ‘horn’ at each corner, and many have curly tendrils. Wikipedia
  6. 33 Small-spotted catsharks lay egg cases with long tendrils, mostly fixed to seaweed in shallow coastal water. Wikipedia
  7. 34 A catshark embryo develops in its case for 5 to 11 months, depending on the sea temperature, and hatches at 9 to 10 cm long. Wikipedia
  8. 35 Horn sharks lay auger-shaped (corkscrew) egg cases, and the mother picks them up and wedges them into crevices. Wikipedia
  9. 36 Horn sharks lay up to 24 eggs between February and April. Wikipedia
  10. 37 Epaulette sharks lay pairs of egg capsules about every 14 days from August to December. Wikipedia
  11. 38 Zebra sharks lay several dozen large egg capsules and anchor them with sticky tendrils. Wikipedia
  12. 39 Great white sharks keep their eggs inside: the eggs hatch in the mother and the embryos carry on growing there. Wikipedia
  13. 40 The tiger shark’s eggs hatch inside the mother and the young are born live once fully developed. Wikipedia
  14. 41 Nurse sharks are ovoviviparous: the eggs hatch inside the female. Wikipedia
  15. 42 Lemon sharks are viviparous: the mother feeds her young through a yolk-sac placenta. Wikipedia
  16. 43 Wobbegongs give birth to live young, in litters. Wikipedia
  17. 44 Inside a pregnant sand tiger shark, the biggest embryo eats its brothers and sisters. Scientists call this intrauterine cannibalism. Wikipedia
  18. 45 The spiny dogfish has one of the longest pregnancies of any animal: about 18 to 24 months. Wikipedia
  19. 46 A frilled shark’s pregnancy may last up to three and a half years. Wikipedia
  20. 47 Greenland shark pups are born alive after a pregnancy estimated at 8 to 18 years. Wikipedia
  21. 48 Blue sharks give birth to live young and are known for big litters of 25 to over 100 pups. Wikipedia
  22. 49 A whale shark caught in 1996 was carrying about 300 pups, which showed that whale sharks keep their eggs inside the body until they hatch. Wikipedia
  23. 50 Lemon sharks return to particular nursery sites to breed. Wikipedia
  24. 51 The Shark Trust’s Great Eggcase Hunt began in 2003, after a chance find on a beach in Devon. Anyone can join in by finding and recording egg cases. Shark Trust

Giants

  1. 52 The whale shark is the largest known living fish. A whale shark 18.8 m (61.7 ft) long is considered the largest reliably recorded. Wikipedia
  2. 53 It’s a filter feeder, eating plankton, krill, fish eggs and small fish, and can filter over 6,000 litres of water an hour. Wikipedia
  3. 54 Each whale shark’s pattern of pale spots and stripes is unique to that individual. Wikipedia
  4. 55 Whale sharks are thought to live for between 80 and 130 years. Wikipedia
  5. 56 The basking shark is the second-largest living fish, after the whale shark. Wikipedia
  6. 57 It is one of only three plankton-eating sharks, along with the whale shark and the megamouth. Wikipedia
  7. 58 An average adult basking shark is around 7.9 m (26 ft) long. Wikipedia
  8. 59 It strains plankton from the water with dark, bristle-like gill rakers. Wikipedia
  9. 60 Basking sharks feed slowly, at about 2 knots (3.7 km/h), and don’t swim away from approaching boats. Wikipedia
  10. 61 The megamouth was discovered in 1976 and is rarely seen. As of 25 March 2025, only 296 had ever been caught or sighted (figure from Sharkman’s World Organization, via Wikipedia). Wikipedia
  11. 62 Megalodon was a giant shark that lived about 23 to 3.6 million years ago. It is extinct. Wikipedia
  12. 63 Megalodon’s jaws could bite with a force of up to 108,500 to 182,200 newtons. Wikipedia

Hunters

  1. 64 A great white shark has around 300 teeth, arranged in rows like a conveyor belt; teeth at the back move forward to replace the front ones. Wikipedia
  2. 65 Great white sharks are thought to live for more than 70 years. Wikipedia
  3. 66 Its fearsome reputation owes a lot to the 1974 novel Jaws and the 1975 film. In reality, white sharks don’t normally prey on humans. Wikipedia
  4. 67 Tiger sharks are named for the dark stripes down their bodies, which fade as they grow up. Wikipedia
  5. 68 Female tiger sharks can grow over 5 m (16 ft 5 in) long. Wikipedia
  6. 69 Tiger sharks eat fish, seals, birds, squid, turtles, sea snakes and even smaller sharks, and are known as ‘garbage eaters’ for swallowing man-made objects. Wikipedia
  7. 70 Hammerheads are named for their flattened, T-shaped heads, called cephalofoils, with an eye at each end. Wikipedia
  8. 71 The eye position gives hammerheads 360° vision in the vertical plane: they can see above and below at all times. Wikipedia
  9. 72 Unlike most sharks, some hammerheads gather in large schools by day and hunt alone at night. Wikipedia
  10. 73 The great hammerhead, the largest hammerhead, reaches up to 6.2 m (20 ft). It specialises in eating rays, especially stingrays. Wikipedia
  11. 74 Bull sharks can live in salt and fresh water, and have been found up the Mississippi as far as Alton, Illinois, about 1,100 km from the sea. Wikipedia
  12. 75 One bull shark was found 4,000 km up the Amazon, at Iquitos in Peru. Wikipedia
  13. 76 Weight for weight, the bull shark has the strongest bite of any cartilaginous fish studied: up to 5,914 newtons. Wikipedia
  14. 77 The shortfin mako is the fastest known shark, reaching 74 km/h (46 mph) in bursts. Wikipedia
  15. 78 Makos are famous for leaping high out of the water when hooked; some have jumped into boats. Wikipedia
  16. 79 ‘Mako’ comes from the Māori language and means either ‘shark’ or ‘shark tooth’. Wikipedia
  17. 80 Blue sharks migrate long distances, for example from New England to South America. Wikipedia
  18. 81 Big blue sharks can grow to 3.8 m (12 ft) long. Wikipedia
  19. 82 The oceanic whitetip lives in the open ocean and has long, rounded fins with white tips. Wikipedia
  20. 83 Oceanic whitetips are known to follow pilot whales, as both hunt squid. Wikipedia
  21. 84 About half the length of a common thresher is its tail, which it uses like a whip to stun fish. Wikipedia
  22. 85 Common threshers reach 6 m (20 ft) long. Wikipedia

Reef and seabed

  1. 86 Nurse sharks are suction feeders, and their suction is among the strongest recorded for any water-living animal with a backbone. Wikipedia
  2. 87 Nurse sharks hunt alone at night but often rest together in big groups during the day. Wikipedia
  3. 88 Bottom-dwelling sharks such as the nurse shark are heavier than water, so they can rest on the sea floor. Wikipedia
  4. 89 Whitetip reef sharks spend much of the day resting in caves. Unlike most of their relatives, they can pump water over their gills while lying still. Wikipedia
  5. 90 The whitetip reef shark doesn’t usually grow beyond 1.6 m (5.2 ft). Wikipedia
  6. 91 The small-spotted catshark lives from Norway and the British Isles south to Senegal, and in the Mediterranean. It grows to about 1 m. Wikipedia
  7. 92 In its 2021 assessment, the IUCN listed the small-spotted catshark as Least Concern. Wikipedia
  8. 93 Angel sharks have flattened bodies and lie in wait on sandy seabeds to ambush prey. Wikipedia
  9. 94 Epaulette sharks often ‘walk’ across the reef, wriggling and pushing with their fins. Wikipedia
  10. 95 When threatened, a swell shark can swallow water and blow up to about twice its normal size. Wikipedia

The deep

  1. 96 The Greenland shark has the longest lifespan of any known vertebrate: an estimated 272 to 510 years. Wikipedia
  2. 97 Greenland sharks only reach adulthood at around 150 years old. Wikipedia
  3. 98 It has the lowest swim speed for its size of any fish, averaging about 0.34 m a second. Wikipedia
  4. 99 Greenland sharks often have a small crustacean, a copepod, hanging from their eyes. Wikipedia
  5. 100 Greenland shark meat is toxic to mammals unless treated; in Iceland a treated, pungent version, kæstur hákarl, is eaten. Wikipedia
  6. 101 The goblin shark is a rare deep-sea shark, the only living member of a family some 125 million years old. Wikipedia
  7. 102 It has a long, flat snout and jaws that shoot forward to grab prey. Wikipedia
  8. 103 Living goblin sharks are pink or tan because blood vessels show through the skin. Wikipedia
  9. 104 The frilled shark is called a living fossil because of its eel-like body and other primitive features. Wikipedia
  10. 105 It swallows prey whole, using long, flexible jaws armed with 300 needle-like teeth. Wikipedia
  11. 107 Its belly glows green, the strongest glow known in any shark. Wikipedia
  12. 108 In the 1970s, several US Navy submarines had to return to base to repair cookiecutter bites. Wikipedia
  13. 109 Cookiecutters are small: the longest recorded was 56 cm, a female. Wikipedia
  14. 110 The dwarf lanternshark is the smallest shark in the world, reaching a maximum known length of 20 cm (8 in). Wikipedia
  15. 111 Like its relatives, it can make light from special organs called photophores. Wikipedia

Isle of Man and British waters

  1. 112 Between May and August, basking sharks feed on plankton blooms around the Isle of Man. Manx Wildlife Trust
  2. 113 They can turn up all round the island, but the stretch from Peel down to the Calf of Man is where they are most reliably found. Manx Wildlife Trust
  3. 114 Most sightings are on the west and south-west coasts, often within a kilometre of the shore. Hot spots are Niarbyl, Port Erin, Peel and the Sound. Manx Whale and Dolphin Watch
  4. 115 Manx Whale and Dolphin Watch’s basking shark page (checked October 2026) says basking sharks, once a frequent sight around the island, are shifting their range, and it is seeing fewer sightings every year. Manx Whale and Dolphin Watch
  5. 116 People sometimes mistake the dorsal fin and tail of one basking shark for two sharks. Manx Whale and Dolphin Watch
  6. 117 The Shark Trust’s British sharks page (checked October 2026) says more than 40 shark species are found in British waters, and at least 21 live there all year round. Shark Trust

Threats and conservation

  1. 118 A 2021 study in Nature found that, since 1970, the number of oceanic sharks and rays had fallen by 71%, driven by an 18-fold increase in fishing pressure. Nature
  2. 119 The same study found that three-quarters of the oceanic shark and ray species it looked at were threatened with extinction. Nature
  3. 120 A study estimated that people killed about 97 million sharks in 2010, with a possible range of 63 to 273 million that year. Wikipedia
  4. 121 Shark finning means cutting off a shark’s fins and throwing the rest of the shark back into the sea, often still alive. Many countries have banned it or require sharks to be landed whole. Wikipedia
  5. 122 Finning grew from 1997, largely because of demand for shark fin soup and traditional cures. Wikipedia
  6. 123 A 2006 study of shark fin trade data estimated that 26 to 73 million sharks a year were being caught for their fins. Wikipedia
  7. 124 In its 2016 assessment, the IUCN listed the whale shark as Endangered. Wikipedia
  8. 125 In its 2019 assessment (updated in 2021), the IUCN listed the basking shark as Endangered. Wikipedia
  9. 126 In its 2019 assessment (updated in 2022), the IUCN listed the great white as Vulnerable worldwide. Wikipedia
  10. 127 In its 2019 assessment, the IUCN listed the tiger shark as Near Threatened. Wikipedia
  11. 128 In its 2021 assessment, the IUCN listed the bull shark as Vulnerable. Wikipedia
  12. 129 In 2019, the IUCN moved the shortfin mako up from Vulnerable to Endangered. Wikipedia
  13. 130 In its 2019 assessment, the IUCN listed the blue shark as Near Threatened. Wikipedia
  14. 131 In its 2020 assessment, the IUCN listed the whitetip reef shark as Vulnerable. Wikipedia
  15. 132 In its 2019 assessment, the IUCN listed the oceanic whitetip as Critically Endangered. Wikipedia
  16. 133 The angel shark (Squatina squatina), once common in the north-east Atlantic, was classified as Critically Endangered in 2010, and an IUCN assessment in 2019 confirmed that status. Wikipedia

Bites

  1. 134 The International Shark Attack File confirmed 65 unprovoked shark bites worldwide in 2025, in line with its 2020–2024 average of 61 a year. ISAF
  2. 135 It also confirmed 12 shark-related deaths in 2025, nine of them unprovoked. ISAF
  3. 136 Humans are not part of a shark’s normal diet. Wikipedia