Sharks aren't just scary-looking and deadly. They're also superpowered. They rarely get sick, never sleep, and possess sensory organs all over their bodies that allow them to smell electricity and see vibrations.
Here are ten reasons (plus a bonus extra reason) to bow down before your shark overlords.
1. Sharks don't get tumors
A substance called squalamine in sharks prevents them from getting tumors. Squalamine suppresses the growth of blood vessels in any tumors that form, which starves the tumors of oxygen and food and kills them before they become deadly. For the most part, sharks are completely tumor-free (though there are rare exceptions). Scientists are trying to use squalamine in cancer treatments for humans too.
2. Sharks evolved millions of years before you did
The earliest sharks evolved hundreds of millions of years ago, when dinosaurs still shook the Earth with their footsteps. Plus, the oldest known fossil of a brain ever found belonged to an ancestor of the shark who lived 300 million years ago. Over time, sharks have evolved very little, though some scientists believe that their sensory organs have gotten more sophisticated over time.
3. Sharks have teeth that are sensory organs
Shark teeth are connected to their nervous system, and they can likely feel temperature and motion with them. They also have multiple rows of teeth that can rotate in their mouths, moving forward and backward as needed.
4. Sharks have no bones
Though they are fierce and feel things with their teeth, sharks have no ribcage and their skeletons are all made of cartilage - the soft, fibrous stuff that you have in your nose and ears. This allows sharks to move extremely rapidly because they are much lighter than other marine creatures. It also means that if they are beached, they will collapse under their own weight and crush their organs, because they have no hard bones.
5. Sharks smell in 3D
Sharks can smell a teaspoon full of blood in a body of water the size of Loch Ness. They move toward prey within less than a second after smelling it, because they're able to distinguish which nostril received the scent first, and then zoom in the direction of that nostril. This gives them essentially a 3D sense of smell, which gives them a sense of where the smell is coming from as well as what it is. 14 percent of the shark's brain is devoted to the olfactory, or smell, system.
6. Sharks can also smell electrical fields, using a sense called "electroreception."
Slate's Daniel Engber explains:
Electroreceptive organs (or "ampullae of Lorenzini") sit inside little pores on the shark's snout. Living things submerged in salty seawater produce a faint electrical field that the shark can feel at short distances, allowing it to suss out creatures that bury themselves in the sea floor. Muscle contractions also produce little surges of electrical activity that a shark can detect using electroreception. (Research suggests that some sharks may use electroreception like a compass, to help navigate underwater.)
7. Sharks have ears all over their bodies
Running down the sides of shark's bodies is a set of sensory organs called the "lateral line." It is partly made up of the electroreceptors that allow the sharks to pick up DC and AC electrical fields. But it is also packed with "neuromasts," which scientists say "consist of canal receptors and pit organs and are mechanoreceptors that are sensitive to water movements caused by external sources as well as the animal's own swimming movements." Basically they are underwater ears, or perhaps a combination of ears and motion detectors. Either way, they mean that any movement in the water near any part of the shark will be instantly picked up - and possibly subject to attack.
8. Sharks have self-cleaning skin that allows them to move ultra-fast through the water
Shark skins are covered in tiny, sharp scales, resulting in the common observation that they are smooth when stroked head to tail, but will cut you up if you stroke them tail to head (also, tip of the day: don't stroke sharks anyway). But shark skin isn't just there to mess you up. It also creates a cushion that allows sharks to slide rapidly through the water. As one shark guide put it, "Shark skin has . .. . dermal denticles. By trapping the water underneath [the] little dermal denticles, it basically creates, like, a cushion where the shark can glide through the water much easier." Dermal denticles also keep shark skin free of pests and barnacles, which basically means it is self-cleaning.
9. They can swim across the world in less than a year
Great white sharks can swim 12,400 miles in 9 months. This is the fastest and lengthiest migration of any sea creature ever recorded.
10. Sharks never fall completely asleep
Sharks breathe by moving through the water, pulling oxygen water as it moves through their bodies. As a result, they can't ever fall completely asleep - they have to keep swimming. Recent studies demonstrate that they do this by shutting down parts of their brains, essentially falling asleep in in different regions of their brains at a time.
BONUS superpower: Sharks can be born by immaculate conception
When no male sharks are available, female sharks can have children via parthenogenesis, which means they can fertilize themselves. That's right - sharks can survive and have children without sex. They are basically unstoppable.
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