It is not possible to know for certain what would have happened in a fight between a megalodon and a blue whale, as megalodon sharks became extinct roughly two million years ago. Owing to the jaw size and power of the megalodon shark, it could certainly pierce the flesh of a blue whale. If the megalodon hunted in groups like modern sharks, a few sharks could have overpowered the whale.
Findings suggest that megalodons weighed up to 50 tons, which is still smaller than blue whales; they top out at more than 200 tons. These giant sharks had teeth up to seven inches long, compared to just 2 to 3 inches on the largest great white sharks. Scientists theorize that the largest megalodon specimens may have grown up to 60 feet long. Although smaller than the 100-foot blue whale, megalodons fed on large fish and aquatic mammals. This means they would probably have had strategies for killing the less dangerous blue whale, which feeds primarily on small krill. Blue whales are baleen whales, and do not kill their prey by biting. Instead the whale swallows a vast volume of water, and then uses its tongue to expel the water through gaps in the interlocking baleen plates of its upper jaws.
Although the megalodon, which means "giant tooth" in Latin, did not fight blue whales, scientists believe the extinct sperm whale known as "Leviathan melvillei" may have competed with megalodons for food, including baleen whales. Palaeontologists recovered a leviathan skull in a Peruvian desert in 2010 that was more than nine feet long. Overall estimates of the creature's length are between 45 and 57 feet long.