Shark facts

●    Sharks date back millions of years, existing on Earth before dinosaurs and even trees
●    In 2016, scientists discovered a Greenland shark aged 400 years old
●    Shortfin mako sharks can swim faster than 70km/h
●    Sharks can propel themselves up out of water, several metres into the air
●    The largest species of shark – whale sharks – can reach an enormous 18 metres in length, and mainly feed on plankton
●    Some sharks can smell as little as one drop of a chemical substance in a mass of water the size of a swimming pool
●    Some sharks can detect as little as 125 microvolts of electric charge in their surroundings
●    Recent research has helped to refute the claim that all sharks are solitary: some have been discovered living alongside the same companions for years
●    Sharks are intelligent creatures: they can learn and remember information for up to 50 weeks, according to one study (1) 

Since sharks have skeletons made of cartilage and not bone, finding traces of prehistoric sharks is no easy feat – but experts have been able to find quite a few fossilised shark teeth and scales to reconstruct its origin story.² On this evidence, it seems that ancient, shark-like creatures were already around 200 million years before dinosaurs roamed the planet, and even before trees sprouted on Earth.³

Some shark ancestor fossils place their origin back all the way to the Devonian Period, which started around 420 million years ago.⁴ By the time of the Carboniferous period, around 360 million years ago, sharks had started to exponentially diversify their populations.⁵ Fast forward to 145 million years ago, during the Cretaceous period, and some of the types of present-day sharks which we live alongside were already well-established. 

That’s why sharks are sometimes called ‘living fossils’: they’ve survived five mass extinctions.

Although one distinct image comes to mind when thinking about sharks – a fusiform (spindle-shaped) body, large mouth, sharp jagged teeth – there are actually over 500 different species of sharks grouped in eight orders.⁶ There are angel sharks, saw sharks, bullhead sharks, mackerel sharks, dogfish sharks, cow and frilled sharks, carpet sharks, ground sharks and many more. 

They each have their own quirks and behaviours and can look quite unique. Great white sharks are big, grey and white; blue sharks are coloured a bright, metallic, electric blue. Prehistoric frilled sharks are brown and have long, elongated bodies which make them look more like snakes than fish.⁷ Goblin sharks can be bright pink, and they have a pointy, fantasy-creature-like nose sticking out of their head.⁸ Catsharks can have spots, stripes, or patches all over their body, and sometimes even glow in the dark.⁹ Wobbegong sharks have evolved to perfectly blend with the seafloor: they don intricate geometric algae and coral-like patterns all over their back and have frilly skin flaps like a shaggy rug.¹⁰ Zebra sharks are born with flashy stripes which turn into spots as they grow older.¹¹

Although they can grow large and become hefty like dolphins or whales, sharks are not mammals, they are fish. They are part of the same group of animals as rays and skates, which is known scientifically as the subclass Selachii.¹² Like fish, most sharks are cold-blooded and rely on their surroundings to set their body temperatures. They are cartilaginous fish though, so instead of having bones, their skeleton is made of the same material as our ears and nose.

Sharks can vary widely in size.¹³ Some sharks can grow really big: the largest shark, the whale shark, can grow to gargantuan 18 metres in length – the length of a volleyball court – or even longer.¹⁴ The basking shark can measure up to about 12m from head to tail.¹⁵ Whale sharks can weigh anywhere between 15 and 30 tonnes, with basking sharks tipping the scales at around five to seven tonnes on average. Both are gentle giants which only feed on plankton. 

Two-thirds of all shark species, though, are less than one metre long.¹⁶ The smallest shark, the dwarf lantern shark, is about the size of a human hand, measuring around 17cm.¹⁷

Sharks have been around for a long time, making a home in all sorts of different marine habitats, including the open ocean, shallow coral reefs and sandy plains.¹⁸

The Greenland shark slowly patrols the frigid water under the ice of the Arctic.¹⁹ Lemon sharks and sandbar sharks like to swim in estuaries where freshwater rivers meet salty oceans.²⁰ Bull sharks and spear tooth sharks often swim up freshwater rivers too, so much so that some bull sharks have been found 3,000km up the Tigris, Amazon and Mississippi Rivers.²¹

Sharks spend a lot of time swimming, but when they require shelter, they can hide on the sea floor and tuck themselves under the sand, or find refuge in crevices of coral reefs and caves.²² Scientists have discovered that some sharks have even turned clumps of scrubby sea sponges in coral reefs into a suitable habitat.²³

Sharks don’t always stay put in one place: many species migrate across long distances to find food, mate, give birth, or escape the colder waters of winter.²⁴

Great white sharks have really complex migratory routes that still baffle researchers.²⁵ In America, they will travel from the coast of California to the coast of Hawaii every year, stopping for feeding halfway in an area in the middle of the ocean now dubbed the White Shark Café.²⁶ Some great white sharks from South Africa have made a similar trip all the way to Australia, traversing more than 20,000km of ocean waters in less than nine months.²⁷

Hammerhead sharks make trips from the Galapagos to Costa Rica.²⁸ Tiger sharks migrate from the coast of Florida and The Bahamas in the winter, and to the deep waters of Bermuda during the summer. Since temperatures are getting warmer due to climate change, they’re now moving almost 300 miles further north than Florida, too.²⁹

In a 2021 experiment, researchers fooled 20 young bonnethead sharks into changing direction by changing the magnetic field of their environment, finally starting to corroborate the hunch scientists have long had that sharks use the magnetic fields of the Earth to get around such large distances, just like sea turtles.³⁰

Most sharks have six to eight different fins.³¹ The large tail fin helps to propel the shark through water. Fast, large sharks have more symmetrical tail fins to swiftly dart through the water. Thresher sharks have long, sword-like tail fins, which they use to slap fish before eating them.³²

Sharks usually have one or two fins on their back to help them avoid tipping over.³³ When seen on film or television, the larger of these can usually be spotted sticking out of the surface of the sea.³⁴ In the case of the Pacific spiny dogfish shark, those dorsal fins are venomous.³⁵

There’s also a tiny fin sticking out of the shark’s anus area for stability, and two pelvic fins for stability, steering, and depositing sperm.³⁶ A pair of pectoral fins help to keep sharks suspended in water, providing direction and speed as they swim.³⁷ Surprisingly, bamboo and epaulette sharks use their pelvic and pectoral fins to walk on land.³⁸

Sharks have impressive vision — in clear water, they can see almost 10 times better than humans. As their eyes are on either side of their heads, many sharks can see an almost 360° view of their surroundings. Sharks can see contrast between light and dark very well, and they can see very far into the distance. While most sharks are colourblind, research shows some can see colour too. Plus, sharks also have a special feature called the tapetum lucidum, which helps them see in the dark of the deep sea and murky waters.³⁹

Scientists also think the size of a shark’s eyes might depend on its habitat.⁴⁰ Sharks living in shallow waters tend to have the smallest eyes, probably to protect them from sand and sediment floating around. Sharks that hunt near the ocean water surface have pretty big eyes, most likely because the waters are clearer, bathed in sunshine and easier to see in.

Although sharks have two eyelids, they don’t blink: they drape their lids over their eyes when they’re going in for the kill to protect them from damage.⁴¹ Some species have a third, tough, translucent membrane which moves from left to right across their eye for the same reason.⁴² Some sharks don’t have any of these special tricks, so they roll their eyes backwards when they’re hunting.⁴³

As well as having good eyesight, sharks have a great sense of smell. While it was initially thought sharks could smell one drop of blood from miles away, that is, in fact, an exaggeration. Studies have shown that different species of shark can detect different types of chemicals – like a drop of blood or ten drops of tuna oil – in a mass of water the size of a small swimming pool.⁴⁴

A shark’s two nostrils can pick up scent separately, which means that it can determine which way it’s prey is coming from, similar to how humans detect sound, and can swim towards the direction of the scent.⁴⁵

Although we may think of sensing electrical signals as a sixth sense, it is one of the shark’s three main senses and they can do it in water. The small holes in their snouts – called the ampullae of Lorenzini – are filled with a sensitive gel able to pick up the tiny electric fields that all animals make when they contract their muscles.⁴⁶ Sharks use these signals to precisely pounce once they’re close to catching their prey. White sharks can pick up charges of as little as 125 microvolts.⁴⁷

Sharks can also detect vibrations in the water thanks to a strip of sensitive fluid-filled cells running down the side of their body – the lateral line – which is connected to the ears, and can detect whether the water pressure around the shark’s body has changed.⁴⁸

While fish have one gill slit on each side, most sharks actually have five different gill slits. As their names suggest, bluntnose sixgill sharks have six and broadnose sevengill sharks have seven. Sharks breathe by inhaling seawater through their mouth and passing it through their gills, which extracts oxygen from it.⁴⁹

Some species, like nurse sharks, can do this with the help of muscles in their cheeks and can actively suck the water into their mouths. Other sharks, such as great white sharks and shortfin mako sharks, don’t have these pump-like muscles inside their mouth, so they have to swim to make sure new water is passing through their gills.⁵⁰

While some sharks need to constantly move to keep oxygen-rich water flowing through their mouth and over their gills, those species that can suck the water into their mouth with their cheek muscles and pharynx can take a rest and lie around lazily whenever they want.⁵¹

Sharks don’t have a swim bladder – the organ that makes most fish buoyant. They have a lightweight cartilaginous skeleton, a large liver full of oil that is less dense than water, and pectoral fins for stability – but constantly swimming does help to ensure that they don’t sink to the bottom too.⁵²

Most of the time, sharks gracefully cruise around at about 2.4km/h. But when it’s time to attack and catch prey, some species can accelerate to impressive speeds. Their torpedo-shaped heads make it really easy to quickly break through water.⁵³

Great white sharks can swim at speeds of up to 50km/h, whilst shortfin mako sharks have been recorded surpassing 70km/h, earning them the nickname, the ‘cheetahs of the ocean’.⁵⁴ These sharks swim so fast that they can shoot themselves out of water, reaching up to 6m high in the sky.⁵⁵ Measuring the speed of these gigantic creatures out in the wild isn’t exactly easy, though, so more research is needed to find out further information about these ‘flying’ fish.

Another feature which makes sharks speedy is their unique skin: they’re covered in millions of small, armour-like dented scales.⁵⁶ These scales are made of the same material as human teeth, and feel like sandpaper if stroked from tail to head.⁵⁷ They’re really helpful for streamlining movement and for making sharks super-fast.⁵⁸

As cold-blooded animals need a lot less energy than mammals, sharks don’t actually eat much. Studies suggest that they eat less than 3% of their body weight each time they hunt, and a total of 10% of their body weight per week, making them much less voracious than previously thought.⁵⁹

The two largest sharks – whale sharks and basking sharks – feed solely on plankton, krill, algae, and tiny shrimp.⁶⁰ They eat by keeping their mouth open as much as possible and filtering water with specialised sieve-like gills. Basking sharks can strain through over 1,800 tonnes of water every hour just by keeping their jaws ajar.⁶¹

Bonnethead sharks were thought to only eat meat, but recent research shows they can live on seagrass-heavy diets too, which technically makes them omnivores.⁶²

Most other species of sharks are still apex predators though, meaning they can eat most of the rest of the creatures inhabiting the waters: smaller sharks, dolphins and seals, turtles, fish of all sorts, octopuses and squids, shellfish and more. 

Some sharks, like nurse sharks, heavily rely on trawling the bottom of the ocean for shellfish and crustaceans.⁶³ They tend to have flatter teeth made more for scraping and grinding.

Great white sharks and Greenland sharks, are known as voracious eaters, chasing seals, orcas and even gigantic whale sharks.⁶⁴ Shortfin mako sharks and thresher sharks can attack large schools of fast-swimming tuna and marlin.⁶⁵ These types of sharks tend to have really sharp teeth to help them to rip their meal apart. Tiger sharks are sometimes dubbed the ‘trash cans of the sea’ because they’ll eat literally anything, even rubbish.⁶⁶

Cookiecutter sharks get their cute-sounding nickname because they have mouths like suction cups. They use these to pierce their prey’s flesh, taking a cookie-shaped bite out of various animals including tuna, whales and much larger sharks.⁶⁷

Sharks are generally considered to be solitary creatures – it’s thought that they don’t like company, and only congregate somewhere if there is a lot of food to eat. But a growing body of research has started to uncover evidence that might suggest otherwise.

One particular piece of research has found that sharks have distinct personalities: some are introverted and others extroverted.⁶⁸ Researchers were also baffled when trackers revealed that two usually solitary great white sharks travelled over 6,000km together without ever separating.⁶⁹ Lemon sharks are very social sharks, and when they’re young they congregate in cliques and learn from each other.⁷⁰ Similarly, grey reef sharks from the Pacific Ocean have been observed hanging out with the same companions for as long as four years.⁷¹

Although several sharks can reproduce asexually, mating in most shark species looks something like this: a male introduces sperm into the female’s body with the tip of their pelvic fin and fertilises the female’s eggs.⁷² For some species, this mating ritual involves a bit of an aggressive tussle.⁷³

Then, some species lay eggs, some grow their offspring in a placenta and give birth to live pups, and others do something in between – their eggs grow and directly hatch while inside of them, and they technically give birth to live young too.⁷⁴

Blue sharks can carry more than 130 pups in one pregnancy, which usually lasts from nine to 12 months.⁷⁵ Basking sharks and frilled sharks are thought to have pregnancies of almost three years.⁷⁶

Sharks that lay eggs release their eggs in rubbery egg cases made of collagen and full of yolk for the pup to feed on while it grows inside.⁷⁷ The egg cases come in all sorts of intriguing shapes, so they’re sometimes called mermaid’s or devil’s purses.⁷⁸ Bullhead sharks lay brown corkscrew-shaped eggs so that they can easily wedge inside rocks and crevices. Catsharks lay egg cases with curly ribbons on each side, to better latch onto algae and the sea floor.⁷⁹ Ghost sharks lay frilled electric-blue eggs.⁸⁰

Once hatched or birthed as live pups, baby sharks take quite a long time to mature. Great white sharks, for instance, were thought to take up to 15 years to become sexually active, but some researchers now suggest it might take them as long as a whopping 26-33 years. In 2024, a great white shark newborn was caught on camera for the first time. Sharks are thought to also live for a very long time because of this really slow and steady development.⁸¹

Scientists analysing traces left from nuclear bomb testing in the 1950s on the vertebrae of sharks have found that great white sharks can live up to 70 years of age, and tiger sharks up to 40.⁸² Using the same technique, it is thought that whale sharks can make it past 100.⁸³

But the prize for longevity goes to Greenland sharks. Exquisitely adapted to life in freezing cold waters, these sharks are thought to regularly live from 250 to 500 years, reaching sexual maturity at 150 years of age.⁸⁴ One carbon dating study discovered a 400-year-old Greenland shark specimen.⁸⁵

Sharks are crucial for the ecosystems they inhabit.⁸⁶ For a lot of coral reefs and seagrass ecosystems, sharks keep the number of other big fish in check, by fulfilling their role as apex predators.⁸⁷ And by munching away at large quantities of algae and plankton, they avoid them overpowering coral reefs.⁸⁸ Research has shown that some seagrass ecosystems without the presence of sharks have a harder time resisting climate change.

Sharks have long suffered from a bad reputation, but they’re not nearly as bloodthirsty and dangerous as they’ve been depicted throughout the decades – especially not towards humans.⁸⁹ Only about 30 species of sharks have been recorded attacking humans; experts estimate that less than 100 shark attacks happen each year worldwide, and just five to 10 of those are fatal.⁹⁰ Humans are more likely to die because a coconut has fallen from a tree and hit them on the head than perish in a shark attack.⁹¹

Crucially, there’s little proof to suggest sharks have ever deliberately targeted humans.⁹² Attacks only tend to happen if sharks are defending their territory, feel harassed, or are very hungry and mistake a swimming, splashing beachgoer for a wounded fish flailing around in the water.⁹³

Sharks are much more scared of humans than we are of them, or at least they should be. Since the 1970s, the global shark population has declined by 70%, making them some of the most threatened vertebrates on Earth.⁹⁴ Almost 36% of all shark species are threatened.⁹⁵

Illegal and unregulated fisheries kill upwards of 100 million sharks each year for shark meat, oil, and shark fin soup – that’s almost 8% of all sharks in the ocean.⁹⁶ And millions more are accidentally caught as bycatch by fishers using aggressive fishing techniques with big nets and longline fishing gear.⁹⁷

Featured image © Galen Neil | Instagram

Fun fact image © Ibrahim Rifath | Unsplash

1. Fuss, Theodora, and Vera Schluessel. 2014. “Something Worth Remembering: Visual Discrimination in Sharks.” Animal Cognition 18 (2): 463–71. https://doi.org/10.1007/s10071-014-0815-3.

2. “Fossil Record of the Chondrichthyes.” Ucmp.berkeley.edu. https://ucmp.berkeley.edu/vertebrates/basalfish/chondrofr.html. ‌

3. Showk, Sedeer el-. 2013. “The First Forests | Accumulating Glitches | Learn Science at Scitable.” Nature.com. July 8, 2013. https://www.nature.com/scitable/blog/accumulating-glitches/the_first_forests/.

4. Frey, Linda, Michael Coates, Michał Ginter, Vachik Hairapetian, Martin Rücklin, Iwan Jerjen, and Christian Klug. 2019. “The Early Elasmobranch Phoebodus : Phylogenetic Relationships, Ecomorphology and a New Time-Scale for Shark Evolution.” Proceedings of the Royal Society B: Biological Sciences 286 (1912): 20191336. https://doi.org/10.1098/rspb.2019.1336.

5. Rogers, Michael. 2016. “A Timeline of Shark Evolution.” Welcome to SharkSider.com! June 10, 2016. https://www.sharksider.com/timeline-shark-evolution/.

6. “Shark Facts: Conservation Status, Habitat, Diet & FAQs.” IFAW. Accessed June 26, 2024. https://www.ifaw.org/international/animals/sharks#:~:text=There%20are%20more%20than%20500.

7. “Frilled Shark.” n.d. Oceana. https://oceana.org/marine-life/frilled-shark/.

8. https://www.facebook.com/OceanPortal. 2018. “The Goblin Shark.” Smithsonian Ocean. May 18, 2018. https://ocean.si.edu/ocean-life/sharks-rays/goblin-shark.

9. “FAMILY Details for Scyliorhinidae - Cat Sharks.” Fishbase.mnhn.fr. Accessed June 26, 2024. https://fishbase.mnhn.fr/Summary/FamilySummary.php?Family=Scyliorhinidae.

Pennisi, Elizabeth. 2019. Review of This Shark Glows Using a Process Previously Unknown to Science. Science. August 8, 2019. https://www.science.org/content/article/shark-glows-using-process-previously-unknown-science.

‌10. “Wobbegong Shark | Smithsonian Ocean.” Ocean.si.edu. https://ocean.si.edu/ocean-life/sharks-rays/wobbegong-shark.

11. “Zebra Shark.” n.d. Oceana. https://oceana.org/marine-life/zebra-shark/.

12. “Selachii | Encyclopedia.com.” Www.encyclopedia.com. https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/selachii.

13. https://www.facebook.com/OceanPortal. 2018. “What Is the Biggest Shark? A Chart Shows the Diversity of Shark Sizes.” Smithsonian Ocean. May 18, 2018. https://ocean.si.edu/ocean-life/sharks-rays/what-biggest-shark-chart-shows-diversity-shark-sizes.

14. McClain, Craig R., Meghan A. Balk, Mark C. Benfield, Trevor A. Branch, Catherine Chen, James Cosgrove, Alistair D. M. Dove, et al. 2015. “Sizing Ocean Giants: Patterns of Intraspecific Size Variation in Marine Megafauna.” PeerJ 3 (January): e715. https://doi.org/10.7717/peerj.715; The Editors of Encyclopaedia Britannica. 2019. “Whale Shark | Size, Diet, & Facts.” In Encyclopædia Britannica. https://www.britannica.com/animal/whale-shark.

15. “Cetorhinus Maximus.” Discover Fishes. Accessed June 26, 2024. https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/cetorhinus-maximus/#:~:text=There%20is%20typically%20a%20wide.

16. Grubbs, Dean, and Charles Cotton. 2015. “Sharks of the Twilight Zone.” Save Our Seas Magazine. December 21, 2015. https://saveourseasmagazine.com/sharks-of-the-twilight-zone/.

17. “Dwarf Lantern Shark | Smithsonian Ocean.” Ocean.si.edu. https://ocean.si.edu/ocean-life/sharks-rays/dwarf-lantern-shark#:~:text=The%20smallest%20shark%2C%20a%20dwarf.

18. “Search for the Distribution of Shark Species.” Shark.swiss. https://shark.swiss/database/distribution.

19. Rafferty, John P. 2024. “Greenland Shark | Size, Age, & Facts.” Encyclopedia Britannica. January 27, 2024. https://www.britannica.com/animal/Greenland-shark.

20. “Negaprion Brevirostris.” Discover Fishes. https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/negaprion-brevirostris/#:~:text=The%20lemon%20shark%20is%20commonly; “Carcharhinus Plumbeus.” 2017. Florida Museum. May 8, 2017. https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharhinus-plumbeus/.

‌21. Shell, Ryan, and Nicholas Gardner. 2021. “Movement of the Bull Shark (Carcharhinus Leucas) in the Upper Mississippi River Basin, North America.” Marine and Fishery Sciences (MAFIS) 34 (2): 263–67. https://doi.org/10.47193/mafis.3422021010607.

22. “Angel Shark.” Save Our Seas Foundation. https://saveourseas.com/worldofsharks/species/angel-shark; “Reef Sharks.” Www.wwfca.org. https://www.wwfca.org/en/species/reef_sharks/.

23. O’Neill, Helen L., William T. White, John J. Pogonoski, Belinda Alvarez, Oliver Gomez, and John K. Keesing. 2024. “Sharks Checking in to the Sponge Hotel: First Internal Use of Sponges of the Genus Agelas and Family Irciniidae by Banded Sand Catsharks Atelomycterus Fasciatus.” Journal of Fish Biology 104 (1): 304–9. https://doi.org/10.1111/jfb.15554.

24. Waddell, Victoria. 2023. “Migration Patterns in Sharks.” ArcGIS StoryMaps. May 3, 2023. https://storymaps.arcgis.com/stories/ee2f5911af5d47a59a93af9dc46a9ca9.

25. Brannen, Peter. 2013. “Tracking the Secret Lives of Great White Sharks.” Wired. December 19, 2013. https://www.wired.com/2013/12/secret-lives-great-white-sharks/.

26. “Voyage to the White Shark Café.” 2018. Schmidt Ocean Institute. May 23, 2018. https://schmidtocean.org/cruise/voyage-white-shark-cafe/.

27. “Great White Shark Swims 12,400 Miles, Shocks Scientists.” 2005. Mongabay Environmental News. October 6, 2005. https://news.mongabay.com/2005/10/great-white-shark-swims-12400-miles-shocks-scientists/.

28. León, Pelayo Salinas de. 2021. “Migration of Pregnant Hammerhead Shark between Galapagos and Isla Del Coco.” Charles Darwin Foundation. April 14, 2021. https://www.darwinfoundation.org/en/news/all-news-stories/migration-of-pregnant-hammerhead-shark-between-galapagos-and-isla-del-coco-documented-from-space-in-real-time/.

29. Hammerschlag, Neil, Laura H. McDonnell, Mitchell J. Rider, Garrett M. Street, Elliott L. Hazen, Lisa J. Natanson, Camilla T. McCandless, et al. 2022. “Ocean Warming Alters the Distributional Range, Migratory Timing, and Spatial Protections of an Apex Predator, the Tiger Shark ( Galeocerdo Cuvier ).” Global Change Biology 28 (6). https://doi.org/10.1111/gcb.16045.

30. Keller, Bryan A., Nathan F. Putman, R. Dean Grubbs, David S. Portnoy, and Timothy P. Murphy. 2021. “Map-like Use of Earth’s Magnetic Field in Sharks.” Current Biology 31 (13): 2881-2886.e3. https://doi.org/10.1016/j.cub.2021.03.103.

‌31. Hoseck, Nicky. 2022. “How Many Fins Do Sharks Have? - Dutch Shark Society.” Www.dutchsharksociety.org. February 28, 2022. https://www.dutchsharksociety.org/how-many-fins-do-sharks-have/.

32. “The Thrashing Thresher Shark | Smithsonian Ocean.” Ocean.si.edu. https://ocean.si.edu/ocean-life/sharks-rays/thrashing-thresher-shark#:~:text=A%20thresher%20shark.

33. “Understanding Shark Fins.” 2016. Welcome to SharkSider.com! July 4, 2016. https://www.sharksider.com/understanding-shark-fins/.

34. OAS. 2009. “OAS - Organization of American States: Democracy for Peace, Security, and Development.” Www.oas.org. August 1, 2009. https://www.oas.org/en/sedi/dsd/Biodiversity/WHMSI/Sharks%20Event/1.5%20ENG%20GUIDE%20for%20IdentifyingSharkFins.pdf.35. “Pacific Spiny Dogfish.” 2024. Montereybayaquarium.org. 2024. https://www.montereybayaquarium.org/animals/animals-a-to-z/pacific-spiny-dogfish#:~:text=Meet%20the%20Pacific%20spiny%20dogfish.

36. “Pelvic Fin - an Overview | ScienceDirect Topics.” Www.sciencedirect.com. https://www.sciencedirect.com/topics/medicine-and-dentistry/pelvic-fin.

3‌7. Mahi, Imtiaz. 2023. “Do Sharks Have Pectoral Fins?” Ocean Fauna. March 8, 2023. https://oceanfauna.com/do-sharks-have-pectoral-fins/.

38. “Hemiscyllium Ocellatum, Epaulette Shark.” Www.fishbase.se. https://www.fishbase.se/summary/hemiscyllium-ocellatum.

39. “Sharks FAQ.” 2017. Florida Museum. May 2, 2017. https://www.floridamuseum.ufl.edu/discover-fish/sharks/faq/; Gill, Victoria. 2011. “Sharks Are Probably Colour-Blind.” News.bbc.co.uk, January 18, 2011. http://news.bbc.co.uk/earth/hi/earth_news/newsid_9365000/9365750.stm; “Sharks | Smithsonian Ocean.” 2018. Ocean.si.edu. April 30, 2018. https://ocean.si.edu/ocean-life/sharks-rays/sharks#:~:text=Like%20a%20human%20eye%2C%20a; Ollivier, F J, D A Samuelson, D E Brooks, P A Lewis, M E Kallberg, and A M Komáromy. 2004. “Comparative Morphology of the Tapetum Lucidum (among Selected Species).” Veterinary Ophthalmology 7 (1): 11–22. https://doi.org/10.1111/j.1463-5224.2004.00318.x.

40. Lisney, Thomas J., and Shaun P. Collin. 2007. “Relative Eye Size in Elasmobranchs.” Brain, Behavior and Evolution 69 (4): 266–79. https://doi.org/10.1159/000100036.

‌41. “Sharks.” 2019. Smithsonian Ocean. October 16, 2019. https://ocean.si.edu/ocean-life/sharks-rays/sharks#:~:text=500%2B%20Species.

42. “Shark Biology.” Discover Fishes. https://www.floridamuseum.ufl.edu/discover-fish/sharks/shark-biology/#:~:text=The%20nictitating%20membrane%20is%20a.

43. Smit, Jessica. 2019. “Don’t Roll Your Eyes at Me.” May 20, 2019. https://www.whitesharkprojects.co.za/news/dont-roll-your-eyes-at-me/.

44. “Sharks and Rays: 6 Myths about Elasmobranchs | AMNH.” 2019. American Museum of Natural History. September 25, 2019. https://www.amnh.org/explore/news-blogs/education-posts/sharks-rays-myths.

‌45. Fang, Janet. 2010. “Timing Is Everything for Sharks That Smell in Stereo.” Nature, June. https://doi.org/10.1038/news.2010.288.

46. “Ampullae of Lorenzini - an Overview | ScienceDirect Topics.” Www.sciencedirect.com. Accessed June 26, 2024. https://www.sciencedirect.com/topics/veterinary-science-and-veterinary-medicine/ampullae-of-lorenzini; “Electroreception.” Www.elasmo-Research.org. http://www.elasmo-research.org/education/white_shark/electroreception.htm.

47. “Electroreception.” Www.elasmo-Research.org. http://www.elasmo-research.org/education/white_shark/electroreception.htm.

48. “A Shark’s Entire Body Is an Ear.” Www.youtube.com. https://www.youtube.com/watch?v=NnVfSjNxFnU.

49. “How Do Sharks Breathe? Do Sharks Have Lungs? | Shark Sider.” 2023. Www.sharksider.com. February 18, 2023. https://www.sharksider.com/how-do-sharks-breathe/.

50. Matthias, Meg. “Do Sharks Really Die If They Stop Swimming?” Encyclopedia Britannica. https://www.britannica.com/story/do-sharks-really-die-if-they-stop-swimming.

51. “Sharks and Rays: 6 Myths about Elasmobranchs | AMNH.” 2019. American Museum of Natural History. September 25, 2019. https://www.amnh.org/explore/news-blogs/education-posts/sharks-rays-myths.

52. Pinte, Nicolas, Mathilde Godefroid, Ouissam Abbas, Vincent Baeten, and Jérôme Mallefet. 2019. “Deep-Sea Sharks: Relation between the Liver’s Buoyancy and Red Aerobic Muscle Volumes, a New Approach.” Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 236 (October): 110520. https://doi.org/10.1016/j.cbpa.2019.06.020; Bartoli, Alex. 2021. “Sharks and Rays: Buoyancy.” SUBMON. July 8, 2021. https://www.submon.org/en/sharks-and-rays-buoyancy/.

53. “How Fast Can a Shark Swim?” Www.elasmo-Research.org. http://www.elasmo-research.org/education/topics/p_shark_speed.htm.

54. “Shortfin Mako Shark.” Oceana. https://oceana.org/marine-life/shortfin-mako-shark/.

55. “How Fast Can a Shark Swim?” Www.elasmo-Research.org. http://www.elasmo-research.org/education/topics/p_shark_speed.htm.

56. Raschi, William, and John Musick. 1984. “Hydrodynamic Aspects of Shark Scales.” Reports, January. https://doi.org/10.21220/V5TQ6B.

57. “Ask an Expert: The Superpowers of Shark Skin.” 2022. South Carolina Aquarium. August 22, 2022. https://scaquarium.org/ask-an-expert-shark-skin/.

58. Dell’Amore, Christine. 2010. “How Shark Scales Give the Predators Deadly Speed.” Animals. November 25, 2010. https://www.nationalgeographic.com/animals/article/101123-shark-scales-speed-animals-environment#:~:text=Sharks%20are%20covered%20in%20flexible.

59. “What Do Sharks Eat? - American Oceans.” 2021. Www.americanoceans.org. November 18, 2021. https://www.americanoceans.org/facts/what-do-sharks-eat/.

60. Review of Fisheries Fact Sheet - Whale Shark. 2011. Government of Western Australia Department Of Fisheries.

61. Leigh, Samantha C., Yannis P. Papastamatiou, and Donovan P. German. 2018. “Seagrass Digestion by a Notorious ‘Carnivore.’” Proceedings of the Royal Society B: Biological Sciences 285 (1886): 20181583. https://doi.org/10.1098/rspb.2018.1583.

62. “Cetorhinus Maximus.” Discover Fishes. Accessed June 27, 2024. https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/cetorhinus-maximus/#:~:text=Food%20is%20strained%20from%20the.

63. “Nurse Shark.” 2024. National Aquarium. January 2, 2024. https://aqua.org/explore/animals/nurse-shark#:~:text=Nocturnal%20and%20generally%20slow%20and.

64. Pethybridge, Heidi R., Christopher C. Parrish, Barry D. Bruce, Jock W. Young, and Peter D. Nichols. 2014. “Lipid, Fatty Acid and Energy Density Profiles of White Sharks: Insights into the Feeding Ecology and Ecophysiology of a Complex Top Predator.” Edited by David William Pond. PLoS ONE 9 (5): e97877. https://doi.org/10.1371/journal.pone.0097877; Long, Douglas. 2019. “White Shark | Size, Diet, Habitat, & Facts.” In Encyclopædia Britannica. https://www.britannica.com/animal/white-shark; ‌Owens, Brian. “White Shark’s Diet May Include Biggest Fish of All: Whale Shark.” New Scientist. Accessed June 27, 2024. https://www.newscientist.com/article/2077291-white-sharks-diet-may-include-biggest-fish-of-all-whale-shark/.

65. NOAA Fisheries. 2019. “Atlantic Shortfin Mako Shark.” NOAA. 2019. https://www.fisheries.noaa.gov/species/atlantic-shortfin-mako-shark.

66. Pfleger, Mariah. 2017. “Shark Fact Friday #14 – Iron Stomach.” Oceana USA. September 8, 2017. https://usa.oceana.org/blog/shark-fact-friday-14-iron-stomach/.

67. “Cookie-Cutter Shark | Smithsonian Ocean.” Ocean.si.edu. https://ocean.si.edu/ocean-life/sharks-rays/cookie-cutter-shark.

68. Jacoby, David M. P., Lauren N. Fear, David W. Sims, and Darren P. Croft. 2014. “Shark Personalities? Repeatability of Social Network Traits in a Widely Distributed Predatory Fish.” Behavioral Ecology and Sociobiology 68 (12): 1995–2003. https://doi.org/10.1007/s00265-014-1805-9.

69. Che, Chang. 2023. “White Sharks May Have ‘Buddies,’ Researchers Say.” The New York Times, August 10, 2023. https://www.nytimes.com/2023/08/10/us/white-shark-pairs-research.html.

70. Guttridge, T.L., S.H. Gruber, K.S. Gledhill, D.P. Croft, D.W. Sims, and J. Krause. 2009. “Social Preferences of Juvenile Lemon Sharks, Negaprion Brevirostris.” Animal Behaviour 78 (2): 543–48. https://doi.org/10.1016/j.anbehav.2009.06.009.

71. Papastamatiou, Yannis P., Thomas W. Bodey, Jennifer E. Caselle, Darcy Bradley, Robin Freeman, Alan M. Friedlander, and David M. P. Jacoby. 2020. “Multiyear Social Stability and Social Information Use in Reef Sharks with Diel Fission–Fusion Dynamics.” Proceedings of the Royal Society B: Biological Sciences 287 (1932): 20201063. https://doi.org/10.1098/rspb.2020.1063.

72. Holtcamp, Wendee. 2009. “Lone Parents: Parthenogenesis in Sharks.” BioScience 59 (7): 546–50. https://doi.org/10.1525/bio.2009.59.7.3.

73. Márquez, Melissa Cristina. “How Do Sharks Mate?” Save Our Seas Foundation. https://saveourseas.com/worldofsharks/how-do-sharks-mate.

74. “Do Sharks Lay Eggs?” Www.nhm.ac.uk. https://www.nhm.ac.uk/discover/do-sharks-lay-eggs.html.

75. Government of Canada, Fisheries and Oceans Canada. 2018. “Blue Shark.” Www.dfo-Mpo.gc.ca. November 23, 2018. https://www.dfo-mpo.gc.ca/species-especes/profiles-profils/blueshark-requinbleu-eng.html.

76. Fisheries, NOAA. 2021. “Eight Surprising Shark Facts | NOAA Fisheries.” NOAA. August 5, 2021. https://www.fisheries.noaa.gov/feature-story/eight-surprising-shark-facts#:~:text=Many%20sharks%20are%20viviparous%2C%20meaning.

77. Berkeley Lab. 2022. “How Shark Egg Cases Balance Toughness and Permeability.” ALS. January 25, 2022. https://als.lbl.gov/how-shark-egg-cases-balance-toughness-and-permeability/.

78. Waterpark Tenerife. 2023. “Shark Eggs: A Deep Dive into the Fascinating World of Shark Reproduction.” Water Park Guide. May 28, 2023. https://waterparktenerife.com/shark-eggs/.

79. Nakaya, Kazuhiro, William T. White, and Hsuan-Ching Ho. 2020. “Discovery of a New Mode of Oviparous Reproduction in Sharks and Its Evolutionary Implications.” Scientific Reports 10 (1). https://doi.org/10.1038/s41598-020-68923-1.

80. Etnoyer, Peter. 2008. “Crazy Shark Eggs | Deep Sea News.” Deepseanews.com. September 16, 2008. https://deepseanews.com/2008/09/crazy-shark-eggs/.

81. Natanson, Lisa J., and Gregory B. Skomal. 2015. “Age and Growth of the White Shark, Carcharodon Carcharias, in the Western North Atlantic Ocean.” Marine and Freshwater Research 66 (5): 387. https://doi.org/10.1071/mf14127; Clayton, James. 2024. “Has Great White Shark Newborn Been Caught on Film for the First Time?” BBC News, January 29, 2024, sec. Technology. https://www.bbc.co.uk/news/technology-68104861.

82. Campana, Steven E, Lisa J Natanson, and Sigmund Myklevoll. 2002. “Bomb Dating and Age Determination of Large Pelagic Sharks.” Canadian Journal of Fisheries and Aquatic Sciences 59 (3): 450–55. https://doi.org/10.1139/f02-027; Hamady, Li Ling, Lisa J. Natanson, Gregory B. Skomal, and Simon R. Thorrold. 2014. “Vertebral Bomb Radiocarbon Suggests Extreme Longevity in White Sharks.” Edited by Christopher J. Fulton. PLoS ONE 9 (1): e84006. https://doi.org/10.1371/journal.pone.0084006.

83. Ong, Joyce J. L., Mark G. Meekan, Hua Hsun Hsu, L. Paul Fanning, and Steven E. Campana. 2020. “Annual Bands in Vertebrae Validated by Bomb Radiocarbon Assays Provide Estimates of Age and Growth of Whale Sharks.” Frontiers in Marine Science 7 (April). https://doi.org/10.3389/fmars.2020.00188.

84. “How Long Do Greenland Sharks Live?” Oceanservice.noaa.gov. https://oceanservice.noaa.gov/facts/greenland-shark.html#:~:text=Scientists%20estimate%20the%20Greenland%20shark.

85. Nielsen, J., R. B. Hedeholm, J. Heinemeier, P. G. Bushnell, J. S. Christiansen, J. Olsen, C. B. Ramsey, et al. 2016. “Eye Lens Radiocarbon Reveals Centuries of Longevity in the Greenland Shark (Somniosus Microcephalus).” Science 353 (6300): 702–4. https://doi.org/10.1126/science.aaf1703.

86. Chleback, Lawrence. 2022. “Why Are Sharks Important to the Ecosystem?” Shark Champions. September 28, 2022. https://sharkchampions.org.au/why-are-sharks-important-to-the-ecosystem/#:~:text=Sharks%20keep%20food%20webs%20in.

87. Whitehead, Kelli. 2020. “Why Are Sharks Important?” Save Our Seas Foundation. November 11, 2020. https://saveourseas.com/why-are-sharks-important/.

88. Couto, Nicole. 2016. “How Badly Do Coral Reefs and Sharks Need Each Other?” Oceanbites. June 30, 2016. https://oceanbites.org/coral-reefs-and-sharks/.

89. Edmonds, Molly. 2013. “Shark Facts vs. Shark Myths.” World Wildlife Fund. 2013. https://www.worldwildlife.org/stories/shark-facts-vs-shark-myths; Naylor, Gavin, and Tyler Bowling. 2019. “Yearly Worldwide Shark Attack Summary.” Florida Museum. February 15, 2019. https://www.floridamuseum.ufl.edu/shark-attacks/yearly-worldwide-summary/.

90. Dyvik, Einar H. 2023. “Number of Shark Attacks Worldwide 2020.” Statista. March 21, 2023. https://www.statista.com/statistics/268324/number-of-shark-attacks-worldwide/.

91. Tobin, Barry. 2019. “Sharks - AIMS.” Aims.gov.au. 2019. https://www.aims.gov.au/docs/projectnet/sharks-02.html.

92. Pallardy, Richard. 2019. “Why Do Sharks Attack?” In Encyclopædia Britannica. https://www.britannica.com/story/why-do-sharks-attack.

93. Hart, Nathan. “Please Explain: Why Do Sharks Attack Humans?” Macquarie University. https://www.mq.edu.au/faculty-of-science-and-engineering/news/news/please-explain-why-do-sharks-attack-humans.

94. Pacoureau, Nathan, Cassandra L. Rigby, Peter M. Kyne, Richard B. Sherley, Henning Winker, John K. Carlson, Sonja V. Fordham, et al. 2021. “Half a Century of Global Decline in Oceanic Sharks and Rays.” Nature 589 (7843): 567–71. https://doi.org/10.1038/s41586-020-03173-9.

‌95. “New Global Study Finds Unprecedented Shark and Ray Extinction Risk.” n.d. IUCN SSC Shark Specialist Group. https://www.iucnssg.org/news/new-global-study-finds-unprecedented-shark-and-ray-extinction-risk.

‌96. Worm, Boris, Brendal Davis, Lisa Kettemer, Christine A. Ward-Paige, Demian Chapman, Michael R. Heithaus, Steven T. Kessel, and Samuel H. Gruber. 2013. “Global Catches, Exploitation Rates, and Rebuilding Options for Sharks.” Marine Policy 40 (40): 194–204. https://doi.org/10.1016/j.marpol.2012.12.034.

97. Bettis, Stephanie M. 2017. "Shark Bycatch in Commercial Fisheries: A Global Perspective". Capstone. Nova Southeastern University. Retrieved from NSUWorks, . (331) https://nsuworks.nova.edu/cnso_stucap/331.