The blue whale (Balaenoptera musculus) is the largest mammal found on the planet, perhaps the largest mammal that has ever lived, thought to be even larger than even the largest of the dinosaurs. It belongs to a family of animals known as the rorquals and is termed a baleen whale. Unfortunately, it is currently listed as endangered and was hunted nearly to extinction by the 1960s when hunting was finally banned. The current population of the blue whale is only estimated to be about 12,000 total.
The blue whale is a grayish-blue in color with lighter gray spots across its skin. It has a tiny pointed dorsal fin, located low on its back. The average length is about 75-80 feet (22-24 meters), but the female, the larger of the species, can grow in excess of 80 feet and can weigh over 100 tons.
Blue whales are found all over the world. They migrate to warmer climates in the winter, in tropical and subtropical locations, and frequent colder locations, like the poles, in spring and summer. They usually travel in very small groups, often traveling alone, and can swim very quickly, sometimes reaching speeds of up to 30 miles per hour.
Blue whales eat by filtering food from the water through plates called baleen in their mouths that take the place of normal teeth. They have large pleated grooves on their underbellies that expand, allowing the mouth to take in huge amounts of water, which is pushed through the baleen, leaving the food behind. Their diet consists mostly of plankton and krill, which are small invertebrates that resemble shrimp. The blue whales can eat over 4 tons of these tiny creatures per day during their summer feeding season.
Female blue whales give birth to their young about once every two to three years after a year-long gestation. The baby whale, or calf, is nursed by the mother for the first six to eight months of life and then is weaned but will often stay with the mother for at least a year. The whales reach sexual maturity at around 10 years of age and usually live for 35-40 years, although some records indicate that they may live as long as 80 years.
Blue whales were once termed “sulfur bottom” by the earliest whalers because of micro-organisms and algae that grow on their underbellies, giving a yellowish appearance. They communicate with each other verbally, using small moans, clicks, and buzzes, but they are also considered the loudest animal on earth, able to emit a noise over 150 decibels, which can be heard for hundreds of miles underwater.