Sharks are magnificent creatures, and here's the facts to prove it!
Friday, August 15, 2014, 12:10 PM - As with any large predator species, sharks deserve our wary respect, especially when we intrude upon their environment, but they've developed a pretty bad reputation over the years - one that is mostly undeserved when you really look at the facts. So, in an effort to show how incredibly cool sharks really are, watch Hank Green of the SciShow relate some of these amazing facts to you in the video above, and then read on for the scoop on what else makes sharks so amazing and compelling!
With eyes on the sides of their heads, sharks can see nearly 360 degrees around them. They only have two blind spots in their field of view - one right in front of their snout, and the other directly behind their head.
Don't count on using those blind spots to escape them, though, since their sense of smell is so sensitive that they can detect a single drop of blood dropped into a swimming pool.
You might not think that sharks have ears, but they do (just the inner part), and can hear sounds and track prey up to nearly 250 metres away.
They even have senses that we don't. Using special sensing organs called ampullae of Lorenzini - which are located on the snout - a shark can sense electrical impulses, even those of a beating heart, and hone in on the sound when hunting.
Perhaps something that helped spread their undeserved reputation, the only thing ultimately left behind after a shark dies and decays away are its teeth. That's because, with skeletons made of cartilage, their teeth are the hardest things in their bodies. Sharks can have a few hundred teeth in their mouth at any time. Great Whites have 48 teeth at the ready to bite down on prey, but behind those are another five or so rows of teeth that are set to advance to the 'front line' when a tooth is lost. Sharks will continue to generate new teeth like this throughout their lifetime, and can replace as many as 1,000 teeth every year. Even with all those razor sharp teeth, sharks don't chew their food. They use the teeth to tear chunks off their prey, which are swallowed whole.
The surface of a shark's skin has an usual tooth-shape to it, which not only cuts down on water resistance and makes the shark glide through the water nearly silently, but it also avoids collecting things like algae, barnacles and the like, preserving their streamline appearance.
Sharks are some of the largest predators in the world, but the largest of the shark species aren't even dangerous to us or even most fish. The Basking Shark is half-again as large as a Great White, and the Whale Shark is about twice as large as that most-notorious species. However, both of these are considered 'gentle giants' (unless you're a plankton or a small fish), as they're filter-feeders.
With some shark species, like the bonnethead, the blacktip shark and the zebra shark, females don't even need contact with a male to become pregnant. This parthenogenesis only happens in specific circumstances, such as when males are in very short supply (some documented cases are with lone females in aquariums), and actually results in an offspring, rather than a genetically-identical clone.
Compared to humans and even dinosaurs, sharks are old! While we've been around for about 200,000 years, and dinosaurs stretched back to about 225 million years ago, sharks have been swimming in our oceans for nearly 400 million years!
Nearly all the 'medicinal' uses for sharks are only based on myth and have no backing by science. Sharks are not immune to cancer, and products made from them (like cartilage pills) do not help with cancer treatments or as protection against getting cancer. Their fins have absolutely no nutritional or medicinal value (and they aren't even very tasty). In fact, toxins like methyl mercury from the shark's diet often end up being deposited in their fins, and through most of their body, so eating anything made from them could actually do people harm rather than helping. Also, contrary to some myths, if you cut off a shark's fin, it will not grow back. So, the entire practice of shark finning simply ends with dead or dying sharks being thrown back into the water to drown or be eaten, with absolutely no benefit being passed on to the people consuming the products made from the fins.
While we know a lot about sharks, as evidenced above, we know surprisingly little about them in some areas. As an example, in some cases, we have yet to even find the locations where certain shark species give birth to their young (an important thing to know when trying to protect them from extinction)! They are an important part of the ocean ecosystem, though, so preserving them is necessary for the health of the planet's environment, and also simply so that we can actually have the time to learn everything we can about them!
What would it be like if we didn't have sharks? Joe Hansen, from It's Okay to be Smart, talks about this in the video below (pay particular attention to the ticker in the bottom left corner):
(H/T to Hank Green/SciShow, BBC, HowStuffWorks, Joe Hansen/It's Okay to be Smart, and Shark Guardians for all the great facts!)
CELEBRATE SHARKS!: Come back every day this week for more stories about the awesome nature of sharks. If you have your own questions about these incredible creatures, leave them in the comments section below and we'll answer them later in the week!