Evolution

The Evolution of Sharks



Tweet
Nicki Marks's image for:
"The Evolution of Sharks"
Caption: 
Location: 
Image by: 
©  

Carcharodon carcharias, more commonly known as the great white shark, is one of the most feared creatures on the planet. Sharks have long since been both feared and admired through out the course of history. We have wrote books about, made movies of, and both tried to kill and save the shark over the years.

But where exactly did the shark come from? Some people think that sharks are fish. While it's true that sharks are related to fish, it is a very distant relation that branched off millions of years ago. Four million years ago, in the Devonian Era, there were many fish, like the bony fish, swimming the earth's waters. Eventually a new species evolved known as Chondrichthyes. Over time these evolved into the species we know as sharks and rays.

The oldest known shark is the Megalodon or "Giant Tooth". This was an ancient shark whose fossilized teeth have been found in many parts of the world. They existed 18 million years ago in a time known as the Miocene Period. To give you an example of just how big they were, they could open their jaws up to seven feet high and six feet wide and its body could grown to be 100 feet long! They could easily swallow a person whole.

So are sharks really as dangerous as they are believed to be? There are many debates over this. Some people wish to destroy the shark species entirely while others want to save and preserve it. While great white sharks are one of the most feared, there are actually few reported deaths from shark attacks per year. What, then, is myth and what is fact about the shark?

Myth- Sharks attack people because they mistake them for seals.

It has actually been studied and scientists have reason to believe that sharks can tell the difference. Their behavior when attacking a seal versus attacking a human is different. Why then do sharks attack? We cannot say for sure, but when we think about it, the fact that we are on "their" turf makes us fair game.

Myth- Sharks have poor eyesight.

This is also untrue. Just as they do not mistake people for seals, they actually have very good eye sight. It is true however that sharks have an amazing sense of smell and that they can use their teeth to investigate things. This may be white sharks bite people yet swim away afterwards.

Myth- Sharks cannot survive in fresh water.

While it is rare, there is a certain breed of shark that can survive for short periods in fresh water.

So what is the best way to avoid a shark attack? There are some pretty simple steps that most beach-goers are advised to take. Swim in a group, stay out of the water at dusk, night time, and dawn (this is when sharks like to feed), don't go into the water if you are bleeding, and finally if you see a shark, stay away!

Tweet
More about this author: Nicki Marks

From Around the Web




ARTICLE SOURCES AND CITATIONS