Sharks are prehistoric animals dating back almost 450 million years, even before dinosaurs walked this planet.
Despite their deadly reputation, these beautiful beasts have captured our attention for centuries.
With over 450 different species of sharks, ranging from 8-inch-long dwarf sharks to 40-foot-long whale sharks, there is a world of knowledge we can gain from these majestic apex predators.
Despite being widely portrayed as ruthless predators in pop culture, these unique creatures are still loved and respected as much as they are feared.
To celebrate these fascinating creatures, here are 5 mind-blowing facts about sharks.
1. Sharks Have No Bones, Only Cartilage
A shark’s skeleton is made entirely of cartilage. No bones.
Cartilage is the same soft flexible material that makes up the tip of your nose and ears.
This has its advantages. A cartilage skeleton is flexible, resistant, lightweight and heals faster than bone.
However, when a shark is out of water, they can be easily crushed by their own body weight as they lack rib cages.
When it dies in the ocean, the cartilage skeleton is dissolved by the salt in the sea water, leaving behind the shark’s teeth only.
2. If a Shark Stops Swimming, It Sinks
Some sharks must constantly swim in order to maintain the flow of oxygen-rich water over their gills, “ramming” water into their mouth while swimming and letting it flow out through their gill slits. This is known as ram ventilation.
However, other sharks such as nurse sharks, angel sharks and carpet sharks do not need to keep swimming.
Just like ancient sharks, they use a method called buccal pumping that pulls water into the mouth and over the gills. Therefore, these species of sharks usually just spend most of their time lying on the bottom of the ocean floor.
As sharks evolved, they became more active, causing buccal pumping to become secondary.
Most sharks today are able to switch between buccal pumping and ram ventilation, depending on what they are doing.
3. Male Sharks Bite the Female in Order to Mate
Male sharks practice biting the female, in order to gain their attention.
They have pelvic fins known as ‘claspers’, which they sink into the female shark’s head, gill or pectoral fin in order to mate.
Due to this, the female sharks tend to have bite marks across their bodies after mating. These bites can kill other animals, but female sharks are able to withstand this thanks to a defence mechanism they developed over time.
The cross-section of a female shark’s skin is visibly thicker than that of a male’s, and they also have stronger healing abilities than a male.
4. 66% of a Shark’s Brain Is Devoted to Its Sense of Smell
Sharks require a heightened sense of smell to detect oncoming danger.
A shark’s smell sensors – called olfactory receptors – are highly developed. Research shows that a shark is able to sniff out one part of blood for every one million parts of water.
It can smell even the smallest bits of fish blood and guts dissolved in water.
Only a few molecules of scent are needed for it to smell prey from 100 to 800 metres away.
5. Sharks Can Only Swim Forward As Their Fins Are Stiff
As the pectoral fins of a shark are incapable of bending upwards, they are only able to swim forward. In order to move backward, sharks must use gravity to first sink.
Sharks are unable to stop suddenly too. They must swerve to the side instead to avoid swimming into something or hitting an object in their path.
In fact, all sharks except the great white shark cannot lift their head above water to look for prey, which is probably the reason why it was the chosen species for the Steven Spielberg classic, ‘Jaws’.