Why didn't the shark evolve throughout Earth's existence?

Evolution of species occurs when it is dictated through the natural surroundings. Based on genetic variation and frequency will determine which offsprings survive long enough to reproduce and so on through each generation after.

If sharks have not changed much over time, then there has been no occurence in their habitat which would require certain types of genetically mutated sharks to live on and pass their DNA while the others would die off.

It is about which traits make them able to survive and reproduce. That is essentially how evolution works. If it is necessary for a creature to have particular traits to do this, then those traits will pass on and other inferior traits will not.

I can give you examples of genetic traits that exist in humans which help them survive and look as we do today if you like. But I am sure you got the gist of why sharks have not changed much. They have obviously met no reason to really do so.

Sharks have evolved.
In fact, the tooth of a shark used to be about the size of a voltzwagon beetle.

	comment kid -  722 pts -  (2 years ago)
	For a predator that attacks its prey like a shark wouldn't decreasing in size and speed be losing that extra edge? And that sounds more like de-volving?

	Peep Bunnies -  1248 pts -  (2 years ago)
	No. It doesn't need to be that large anymore. If it was, there wouldn't be enough food for it. The reason they used to be huge is because everything else was huge... ie dinosaurs. =]

The process of evolution is based on survival.Sharks have not changed because they are perfect.You may see larger sharks becoming extinct but smaller sharks will be here long after we are a distant memory.If it isn't broken don't fix it.

	Peep Bunnies -  1248 pts -  (2 years ago)
	Check out the size of the megalodon. =]