The blue whale is the largest animal known to ever live on Earth, weighing in at , pounds , kilograms and stretching up to feet 33 meters. Despite the whale's size, scientists have trouble locating and studying the cetacean in the vastness of the ocean, leaving many questions about the mammal's life history, particularly its mating and courtship behaviors. Blue whales Balaenoptera musculus are found worldwide, with different regional populations forming distinct subspecies. Scientists believe they reach sexual maturity between 5 and 15 years of age, and have a gestation period that lasts 10 to 12 months. Mating and birthing take place during the winter, though the animals don't appear to have a set breeding ground, said Richard Sears, a cetacean researcher with the Mingan Island Cetacean Study.