There are more than 465 known species of sharks living in our oceans today. Sharks are an apex predator at or near the top of their marine food chains, and they regulate the populations of species below them. Research has shown that massive depletion of sharks has cascading effects throughout the ocean’s ecosystems.
1)sharks have no bones.
2)Many species only give birth to one or two pups at a time.
3)The stomachs of tiger sharks have been found with some very unique items inside of them.
4)They can give birth to anywhere from 10 to 80 pups at a time. 
5)Some shark species are oviparous, meaning they lay eggs.
6)Others are viviparous and 
give birth to live young.
7)It is currently thought that the sharks form a polyphyletic group.