The blue whale is the world's largest marine mammal and the largest living animal in the world. The animal, whose scientific name is Balaenoptera musculus, belongs to a suborder called Mysticeti or baleen whales. Adult baleen whales do not have teeth, but instead, they possess baleen plates which are made of keratin. On average, an adult blue whale measures between 70 and 90 feet in length and they weigh between 100 and 150 tons. Due to their large size, blue whales have some of the largest organs in the animal kingdom. Their tongues, for example, weigh around 2.7 tons while the heart of a typical sized adult blue whale weighs about 180 kilograms. However, in spite of their large size, blue whales feed almost exclusively on small crustaceans known as krill.
Habitat and Range
Blue whales inhabit most of the world's major oceans like the Antarctic Ocean, Pacific Ocean, Atlantic Ocean, and the Indian Ocean. In the North Atlantic, these marine mammals can be spotted off Newfoundland, the Gulf of Saint Lawrence, Nova Scotia, Greenland, the Azores, and Iceland. In the Pacific, small blue whale populations can be seen around the Korean Peninsula, in the coastal waters of the Sea of Japan, and off Kushiro. In the Southern Hemisphere, these animals are found in the Antarctic, Oceania, and in areas such as the Madagascar Plateau in the Indian Ocean.
Blue whales have two primary seasons; feeding and mating. The feeding season occurs during the months of summer, and during this time the animals consume a lot of krill to stock up their food reserves in preparation for the migration season. The mating season begins in late autumn and extends to the end of winter which is when the animals migrate towards the warmer waters of the equatorial region to mate with other whales or to bear their offspring. During the mating season, large populations of blue whales can be spotted around Monterey Bay, Channel Islands, Farallon Islands, Costa Rica, the Gulf of Mexico, off Angola, and Mauritania.
Why Migration Is Important for Blue Whales
Migration plays a very crucial role in the survival of blue whales. Typically, these animals tend to inhabit the deep temperate waters of cold regions because most of their food is found in cold waters. However, these cold areas are not ideal for young calves; hence the animals have to migrate to warmer and safer temperate waters to give birth. The reproductive cycle of blue whales lasts between 10 to 12 months, making it easy for the animals to give birth in the same location where mating took place. After giving birth, the calves have enough time to feed on their mothers' milk and stock up energy for the return journey to their feeding grounds.
Currently, the blue whale is listed as an endangered species by the International Union for Conservation of Nature (IUCN). The animals were widely hunted by whalers between the 1860s and 1960s to the point of near-extinction. By the end of the whaling era, it is estimated that more than 330,000 blue whales had been caught in the Antarctic alone, and the original population had been reduced to just 360 individuals. Today, the species is protected by the International Whaling Commission, and since the ban of blue whale hunting in 1966, their numbers are steadily increasing. According to a most recent estimate by the IUCN, the global population of blue whales might be around 10,000 to 25,000.