They were alive before people were alive.
Sharks are meat eaters so they will like to eat fish seals and probable even sharks, also humans
The meglagon also has the name of big tooth. He has two names. He is the biggest shark in all existance. He is 30ft and his jaws are as big as a hotel, if you got eaten by it, it would chop you in half in one bite. Go to the fin free page to stop people finning sharks for shark fin soup. Go check the fin free website.