15 Incredible Facts about Sharks

A lot of us perceive sharks as these bloodthirsty, evil, snapping and biting things. Thanks to movies like Jaws, Deep Blue Sea, etc, they have got a slightly undeserved reputation as the bad guys of the ocean and seas.  However, the more you read about them, the more you realize that these fearsome sea creatures may be one of the most misunderstood of them all. In fact, humans have been proven to be more deadly for them, than vice versa. Read on to find out cool facts about sharks that sound fantastically fake, but are completely true.

1. More people are killed by coconuts, pigs, lightning, and taking selfies, than by sharks. 

Shark and taking Selfie
Image credit: Pixabay

Sharks are definitely not tame or even the friendliest fish in the sea. But they may be less of a danger to us than previously believed. According to the Shark Foundation, people are more likely to win the lottery, get killed by pigs or falling coconuts than get bitten and killed by sharks. New Yorkers are more likely to bite ten times more people than sharks do! Between 1959 and 2003, there were 1,857 people who were killed by lightning in coastal USA alone. During the same time, 740 people were involved in shark accidents, out of which 22 actually died. In Canada and USA, 40 people are killed by pigs each year. That is six times the number killed by sharks. In 2015, 12 people died while attempting to take selfies, as compared to eight shark deaths.(1,2)

2. Sharks have been on earth for 50 million more years than trees! They appeared around 400 million years ago, whereas trees have been around for 350 million years.

Cladoselache Fyleri Fossil
Image credits: James St. John/wikimedia, Nobu Tamura/wikimedia

The Pelagic Shark Research Foundation and the ReefQuest Centre for Shark Research have reported that sharks have lived on earth for approximately 400 to 450 million years. They have been through, and survived, four global mass extinctions. There are now more than 470 species of sharks present worldwide. Interestingly, the earliest known species of trees, Archaeopteris, existed about 350 million years ago, according to a report published in 1999 by three scientists, Brigitte Meyer-Berthaud, Stephen E. Scheckler, and Jobst Wendt.(1,2)

3. Some of Greenland sharks alive today were born before the English Civil war. The world’s oldest shark may have been alive at the same time as William Shakespeare.

Greenland shark aka Somniosus microcephalus and William Shakespeare
Image source: wikimedia, wikimedia

Now, we already know that sharks have been swimming around for hundreds of millions of years. But did you know that the Greenland sharks are also the world’s longest living vertebrates with a lifespan of 272 to 400 years?

In an article published in 2016, by Julius Nielsen of University of Copenhagen and his team, they explain how they used a carbon-14 dating method on the eyes of dead female sharks to determine their age. The oldest was 392 when it was caught, four years before the report was written.(1,2)

4. In a golf course in Brisbane, the local wildlife includes at least six bull sharks who accidentally found themselves in the lake after a flood in 1996 brought them there. They now have a golf tournament named after them.

Bull Shark in Golf Course
Image source: RT video screengrab

Bull sharks are generally known to be aggressive predators who can survive in both seawater and freshwater. Since the flood in 1996, they began to be spotted at the Carbrook Golf course lake after the flood waters receded. They have bred and multiplied since then. Being residents of this Australian golf course has brought them worldwide fame and players have often reported sighting their fins over the water, although the exact number is still not known. They are almost eight to ten feet long, and are sometimes fed meat by the club manager.(1,2)

5. Female sand sharks may have up to 50 embryos, out of which the biggest one cannibalizes the others. Scientists say that it is a “competitive strategy” where the eggs are from different fathers.

Carcharias Taurus aka Sand Shark
Image credit: Amada44/wikimedia

According to the research done by Demian Chapman and his team of marine biologists from Stony Brook University, the largest shark embryo eats all its siblings, save one. They deduced that this happens when the eggs fertilized by different fathers compete and the survivor gets to be born. This is called intrauterine cannibalism, or adelphophagy, which means “eating one’s brother.”(1,2)

6. Sharks can lose as many as 30,000 teeth in their lifespan and regrow them. This is because they are not actually teeth, but scales.

Nurse Shark aka Ginglymostoma Cirratum's teeth
Image source: wikimedia, wikimedia

Shark teeth are actually modified placoid scales having the same structure as teeth. They have an outmost layer of enamel, with dentine and central pulp cavity. Most of them have five rows of teeth, which when damaged, is replaced by the ones in the row behind it. The ones in the front are used and are also the largest. The nurse shark’s teeth in the front row get replaced every ten to 14 days during the summer when it is more energetic, as compared to winter.(1,2)

7. The Great White Sharks have a specific hangout place in the Pacific Ocean called the White Shark Café.

White Shark Café and White Shark
Image credits: Elias Levy/flickr, Obtund/wikimedia

In 2002, researchers from the Monterey Bay Aquarium Research Institute, identified an area between Hawaii and Baja California, where great white sharks from all over coastal America gather in winter and spring. They were tracking these sharks via satellite tags, when they discovered that this species frequented this area of the ocean, and unofficially named it the White Shark Café. However, this area has very little food for them, and it is not their mating ground either. Therefore, the reason for the sharks travelling for as many as 100 days to get to this destination is still not known.(source)

8. Most sharks have the ability to detect electromagnetic fields given off by other animals in the water. This sense is so strong in the Great white sharks that they can even hear heartbeats if their prey is nearby.

Electroreceptors in a shark's head.jpg
Image credit: Chris_huh/wikimedia

Most sharks have the ampulla of Lorenzini, or simply put, sensory organs called electroreceptors. These detect electric fields in water which is given off by animals’ activity in the water. Every living being produces an electric field generated by their muscles contracting, and this is perceived by sharks. The great whites have an even more heightened sense, which enables them to discern variations of “half a billionth of a volt!” This means that they are immediately able to trace other living beings nearby, even if they are not moving, by sensing their heartbeats. This makes them excellent predators.(source)

9. A study has shown that sharks are known to have a rush hour. Shark traffic showed an increase around Palmyra Atoll between seven and eight in the evening.

Palmyra Atoll on map
Image credits: TUBS/wikimedia, Williams et al./wikimedia

The University of California used an acoustic camera, which is a dual-frequency identification sonar, to study sharks. They discovered, that like humans, sharks too had a rush hour around Palmyra Atoll near Hawaii. They observed animals using a World War II dredged channel as a kind of road which led to and from the lagoon. They recorded almost 1200 sharks in a month, coming and going at almost the same time every day. The number significantly increased in the evening between seven and eight. This could be because they are likely to hunt early in the evening.(source)

10. The short fin mako shark is the fastest shark species in the world and is known to be able to leap up to 30 feet or more, in the air.

Isurus oxyrinchus aka Shortfin mako shark
Image credit: NOAA-PIRO Observer Program/wikimedia

The Mako shark is known to have remarkable speed, clocking a record of 25mph with short bursts ranging up to 46mph. This enables it to jump up to 30 feet in the air, with several instances of it jumping onto boats as well. Just this year, in July, a mako shark jumped onboard a fishing boat near Long Island, giving the crew a massive scare. In 2013 close to New Jersey, a 300-pound, eight and a half foot long, shark back flipped onto a boat after being hooked.(1,2)

11. People are known to have shown symptoms of extreme drunkenness after eating the untreated meat of a Greenland shark.

Greenland shark, Hákarl and Sick lady in hospital
Image credits: NOAA Okeanos Explorer Program/wikimedia, Chris 73/wikimedia, Pixabay

Hákarl is the national dish of Iceland, prepared with fermented shark meat which is hung to dry for almost five months. Holly Shiels, a professor of Biology, Medicine and Health at Manchester University says that if eaten untreated, it makes one “shark drunk” due to the toxins, making you dizzy and fall down as well.  The Greenland sharks have a higher content of urea and trimethylamine oxide (TMAO) as compared to other sharks in their bodies. This TMAO gets converted to a poisonous compound by the human body, which is why humans get sick if they eat untreated Greenland shark meat.(source)

12. A great white shark’s bite is not very strong as compared to other mammals like lions or tigers.

Shark V/s Tiger
Image credits: gustavorezende/freestockphotos, Pixabay

According to research, sharks don’t have a strong bite in correlation to their big jaws and sharp teeth. The lead researcher of the study, Dr Daniel Huber from University of Tampa in Florida, said that when compared to other mammals, these sharks have relatively weaker bites. They are able to get prey solely because of their speed, big heads, wide jaws and sharp teeth. The research team studied ten different species of sharks before reaching this conclusion.(source)

13. Sharks have been found living in an active underwater volcano in the South Pacific.

A report in 2015 detailed the studies of a group of scientists who discovered hammerhead sharks, silky sharks and the elusive Pacific sleeper shark, living in Kavachi. Kavachi is one of the most active underwater volcanoes near Vangunu in Solomon Islands, just 60 feet below the surface. What’s incredible is that is that the volcano has hot, acidic water all around it. The team sent down submersible robots with cameras which recorded these sharks living in the volcano. One of the team members, Brennan Phillips, stated that nobody knows how they survive in such inhospitable conditions or whether they get an early warning if the volcano is about to erupt. Kavachi has erupted a number of times in the recent past, the latest one being in 2014.(1,2)

14. There are sharks living in Ganga and Brahmaputra rivers in India.

Glyphis gangeticus aka Ganges Shark
Image credits: Zoological Survey of India/wikimedia, Chris huh, Lupo/wikimedia

They are critically endangered species, as per the International Union for Conservation of Nature. Their population has drastically reduced due to hunting for its fin and jaws. Interestingly, they do not need salt water to survive and do quite well in freshwater of the rivers. They have very small eyes and are thought to be poor sighted, probably because of the prevalence of murky water in these rivers. They are mostly found in the rivers Ganga, Brahmaputra and also in Hooghly and Mahanadi. However, sightings are extremely rare and a lot about them remains a mystery to us.(1,2)

15. A shark may be held in trance for up to 15 minutes if it is flipped onto its back.

Shark into Tonic Immobility
Image credit: Mozcashew1/wikimedia

Tonic immobility in sharks happens when it is flipped onto its back, and enters a state or trance or hypnosis. When this happens, their muscles and respiratory processes relax, their dorsal fins line up straighter and within 60 seconds and they are rendered immobile. Scientists believe that it could relate to mating behavior of sharks since females tend to suffer injuries at the hands of the males while mating. This phenomenon has been seen in whitetip reef sharks, blacktip reef sharks, lemon sharks, sandbar sharks, silky sharks and tiger sharks.

This is a very handy maneuver to know if you want to subdue a shark, and is typically used by researchers to avoid being attacked. In 1997, near Farallon Islands, a female Orca held a white shark upside down, essentially suffocating it by inducing tonic immobility, and then ate it.(1,2)

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