Big and Blue
Scientific name: Balaenoptera musculus
Common name: Blue Whale
Habitat & Facts
Blue whales live in all the world's oceans occasionally swimming in small groups but usually alone or in pairs. They often spend summers feeding in polar waters and undertake lengthy migrations towards the Equator as winter arrives.
These graceful swimmers cruise the ocean at more than five miles an hour (eight kilometers an hour), but accelerate to more than 20 miles an hour (32 kilometers an hour) when they are agitated. Blue whales are among the loudest animals on the planet. They emit a series of pulses, groans, and moans, and it’s thought that, in good conditions, blue whales can hear each other up to 1,000 miles (1,600 kilometers) away. Scientists think they use these vocalizations not only to communicate, but, along with their excellent hearing, to sonar-navigate the lightless ocean depths.
Blue whales look true blue underwater, but on the surface their coloring is more a mottled blue-gray. Their underbellies take on a yellowish hue from the millions of microorganisms that take up residence in their skin. The blue whale has a broad, flat head and a long, tapered body that ends in wide, triangular flukes.
Blue whales reach these mind-boggling dimensions on a diet composed nearly exclusively of tiny shrimplike animals called krill. During certain times of the year, a single adult blue whale consumes about 4 tons (3.6 metric tons) of krill a day.
Blue whales are baleen whales, which means they have fringed plates of fingernail-like material, called baleen, attached to their upper jaws. The giant animals feed by first gulping an enormous mouthful of water, expanding the pleated skin on their throat and belly to take it in. Then the whale's massive tongue forces the water out through the thin, overlapping baleen plates. Thousands of krill are left behind—and then swallowed.
Between 10,000 and 25,000 blue whales are believed to still swim the world's oceans. Aggressive hunting in the 1900s by whalers seeking whale oil drove them to the brink of extinction. Between 1900 and the mid-1960s, some 360,000 blue whales were slaughtered. They finally came under protection with the 1966 International Whaling Commission, but they've managed only a minor recovery since then.
Blue whales have few predators but are known to fall victim to attacks by sharks and killer whales, and many are injured or die each year from impacts with large ships. Blue whales are currently classified as endangered on the World Conservation Union (IUCN) Red List.
Blue whale calves enter the world already ranking among the planet's largest creatures. After about a year inside its mother's womb, a baby blue whale emerges weighing up to 3 tons (2.7 metric tons) and stretching to 25 feet (8 meters). It gorges on nothing but mother's milk and gains about 200 pounds (91 kilograms) every day for its first year.
Sound is the most effective way to communicate across a vast expanse of ocean – travelling at a speed of five times greater under water than in the air - so it’s not surprising then to discover that Blue Whales have evolved the ability to communicate with sound across the water.
Tests and studies have shown that all whale species use sound for a number of different purposes: to navigate, to detect food, and to communicate with one another over long distances.
Blue Whales are relatively solitary animals, usually found alone, or in pairs of mother and calf or two adults, but even then they sometimes swim several kilometres apart.
Due to their solitary lifestyles, Blue Whales have evolved an exceptional way of speaking to one another across huge distances. As you would expect from the largest animal on the planet, Blue Whales have exceptionally deep voices and are able to be vocal at frequencies as low as 14 Hz - well below the ability of human hearing - with a volume greater than 180 decibels, which makes the Blue Whale the loudest animal on the planet.
The sounds they make that humans can hear are characterised by low grunts, humming, moans and clicks. The deep vibrations and sounds created by a Blue Whale can travel thousands of miles across the sea and may have evolved to take advantage of the ocean's sound channel.