Wiktionary(0.00 / 0 votes)Rate this definition: mutant(Noun) Something which has mutated, which has one or more new characteristics from a mutation. mutant(Noun) Someone or something that seems strange, abnormal, or bizarre. mutant(Adjective) That has undergone mutation.
Best Answer: The Blue Whale, Balaenoptera musculus, is the largest mammal living today. It is also the largest mammal to have ever lived. In fact the Blue whale is the largest animal ever to have lived on the planet as far as we know; bigger by far than ever the largest Dinosaur.
iStock/QueGar3. Though not technically immortal, the bowhead whale is the oldest living mammal. According to Popular Science, several species of whales have been known to live for more than 70 years, though in the 1990s scientists discovered scars on the massive animals that had been made by weapons from the 1800s. The oldest known bowhead lived to be 211 years old.