Studies over the last forty years have shown that Blue Whales have evolved sophisticated modes of communication that allow them to speak to one another across immense oceans.
During the darkest days of the Cold War, US Navy officials, listening out for Soviet submarine activity in the northern Pacific Ocean noted that one of the main sounds they continually heard were those of whales, often many miles away, communicating to one another across the sea.
Since scientists have gained access to that network of undersea listening outposts, they have worked to find out if, how and why whales communicate to one another across the oceans.
Blue Whale Sounds
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. Despite the breakthroughs in determining the role of sound in whale activities, much about the Blue Whale sounds remains something of a biological mystery.
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 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.
"One of the challenges in understanding the status of this species is knowing how many are out there," said National Geographic in-house marine biologist John Francis, based at Society headquarters in Washington D.C. Remotely listening to and measuring whale song, which travels for thousands of miles, is one off-beat option.
The Impact of Noise Pollution on Whales
There is increasing evidence to suggest that noise pollution from modern shipping, military sonar activity and leisure boats is having an adverse effect on the way whales communicate and how they act. Although many whale calls are too low for the human ear to pick up, most human noise pollution on the seas is at a similar ambient noise level to that used by whales to communicate, causing possible confusion to the animal as it navigates or looks for a mate.
Scientists at Cornell University in the US, who undertook a study into the effects of noise pollution on Blue Whales believe that twenty to twenty-five million years of evolution are being undone in a hundred years thanks to increased noise pollution from humans.
The Cornell scientists also point out that since the average life span of a Blue Whale is 90 years old, there are whales alive today that might remember when they only heard the calls of other whales across vast stretches of ocean.
Other research shows that Blue Whales are only able to hear up to 100 miles (160 kilometres) away today, compared with the 1,000-mile (1,600-kilometre) acoustic range they had in 1940. The same study even notes that other whale species such as the Right Whale communicate at frequencies two thirds of an octave higher than they did a century ago, possibly a way to combat and communicate above the din of ocean noise pollution.
Scientists believe that the very-low-frequency courtship songs of Blue Whales are the most powerful biological sounds in the ocean and they hypothesize that whale songs evolved to take advantage of the ocean's sound channel, especially for some of their most important kinds of communication, including finding a mate.
Interestingly, only male Blue Whales sing loud songs, suggesting a reproductive reason for the calls, which are potentially being cancelled out by the din of modern shipping.
Potentially, if noise pollution means that Blue Whales are struggling to find mates across the vast ocean waters, it could have a dramatic effect on any attempts to increase their numbers and move them off the endangered species list.
Do Blue Whales Have Dialects?
Although there is no way to know if Blue Whales have accents, research into the calls and sounds of Blue Whales suggests that they may - bizarrely - have different dialects, depending on where in the ocean they are found.
Researchers in the US from the Scripps Institution of Oceanography at the University of California in San Diego undertook a study in 2007 to determine worldwide Blue Whale populations by analysing different song patterns. They found that Blue Whales in different parts of the sea actually make different sounds.
The Scripps team of scientists was able to create a map categorising Blue Whale species types into nine geographical regions around the world based on their song ‘dialects.’
The study found that while some dialects are relatively confined to coastal areas, others are spread over broad geographic areas, such as the entire Northern Pacific Ocean. This lead to suggestions that the stock structures of Blue Whales, traditionally based on International Whaling Commission boundaries, should instead be based on song. By listening to the animals, researchers can tell something about the regions in which the Blue Whales are interacting and breeding, which is important for managing and conserving whale populations.
HOW DOES A BLUE WHALE MOVE?
Blue Whales: Swimming, Diving and Feeding
As everyone knows, the Blue Whale is enormous and is the single largest living animal on the planet, growing up to 30 metres in length when fully mature. Even early whalers stayed clear of the Blue Whale, not only because of its sheer size, capable of capsizing the largest of wooden vessels, but also because it was too fast to pursue in open topped man-powered rowing boats armed with nothing but a harpoon gun.
Blue Whales: Swimming & Migration
Typically, a Blue Whale will swim at a speed of 14 miles per hour, far faster, in comparison, to the Sperm Whale, which travels much slower at 6 miles per hour. However, the Blue Whale is able to swim as fast as thirty miles per hour for short periods, for example when it is fleeing potential danger.
Due to their sheer size Blue Whales consume as much as four tonnes of krill (a small shrimp-like animal) each day. Since they need such a large volume of food, they move quickly from one high productivity area to another, usually at a speedy pace.
Marine mammal expert Bruce Mate, from Oregon State University, tagged one hundred Blue Whales off the coast of California and tracked their movements via satellite throughout much of the 1990s. The research was surprising because it found that Blue Whales travel rapidly from one feeding area to another, and continue to feed throughout the entire year, unlike many other species of whales.
Scientists believe that the huge fat reserves and the rapid movement in search of food have evolved to allow blue whales to survive potentially devastating events. During the strong El Nino of 1998, most migrating whales seen near California were visibly starved.
Like other whale species Blue Whales start migrating to warmer weather in the autumn. But unlike other whales that migrate in large groups and never stop, if an individual Blue Whale comes across a good feeding ground they may stay there for weeks before continuing on its migratory route. Interestingly, even the winter destination of Northern Pacific blue whales—a region off Central America called the Costa Rica Dome—is rich with krill. This points to the necessity of a continuous food supply for Blue Whale survival, as opposed to other species of whale who often forgo feeding in the winter months and rely on fat stores to keep them alive.
Blue Whales and Diving
The Blue Whale typically dives less than 330 feet when feeding and can only stay submerged for 10 to 20 minutes, but is capable of diving as deep as 1,640 feet. In comparison, the Sperm Whale, though a slower swimmer, is the deepest diving whale species alive, capable of diving to depths as low as 3,300 feet (1000 metres) and holding it’s breath for up to an hour. Sperm whales need to be able to dive for longer and deeper because they hunt for giant squid, which live on the bottom of the ocean floor.
How Do Blue Whales Dive?
Scientists have often been puzzled by the ability of marine mammals, such as whales, dolphins and seals to dive to such great depths, which at first glance appear to be well beyond their physical abilities. Recent video studies of marine mammals, including that of a 100 tonne Blue Whale off the coast of northern California, has finally revealed, how exactly, marine mammals dive. Video cameras mounted on the animals' backs revealed that all marine mammals start their dives with a few powerful swimming strokes, before making the rest of the descent in what can best be described as a relaxed glide.
As Blue Whales and other marine mammals dive, they are able to reduce their oxygen consumption by 10 to 50 percent by not actively swimming all the way down. They essentially turn their “motor” on and off as they dive, and coast down the pressure gradient.
The change in buoyancy due to increasing pressure with depth allows marine mammals to sink effortlessly. Interestingly, the range of marine mammals with the same style of diving was striking and includes whales, dolphins and seals. These mammals all have lungs that are designed to collapse progressively with increased pressure at depth so air is forced into the upper part of the respiratory system. The change in depth compresses the animal’s body and forces the air in the lungs into a smaller volume, which changes the buoyancy. They can dive and resurface with ease and without getting the bends, a life-threatening affliction of divers who resurface too quickly from dives.
Humans and other land mammals don’t have the ability to dive and resurface quickly because air gets trapped as the lungs are compressed, which forces nitrogen into the bloodstream and causes the bends. Marine mammals make their dives long by relaxing and consuming less oxygen on the way down.
UNDERSTANDING THE BLUE WHALE
The Blue Whale
The Blue Whale is one of the most extraordinary creatures to ever have existed on the face of the Earth. Even by the super-sizes of the Dinosaurs, the Blue Whale is believed to be one of the largest, if not the largest, of animals ever to inhabit the Earth. It is certainly the largest mammal ever to have lived.
But it’s not just the Blue Whale’s size that makes them extraordinary to naturalists and animal lovers. The fact that they are very shy, rarely seen and their numbers are estimated to be so low, makes them almost mystical creatures.
Blue Whale Facts
According to the American Cetacean Society the longest Blue Whale ever caught was a 108-foot – 33 metre - adult female captured in Antarctica. Typically, though, Blue Whales in the Southern Hemisphere reach lengths of 90-100 feet (30 metres), while Northern Hemisphere Blue Whales are slightly smaller at 25 metres. There is no way that the Blue Whale could live life on land as it is too heavy and needs the water to support its weight: it would be crushed by its own weight on land.
The Blue Whale has an almost U-shaped head and, unlike many other whales, does not appear to have quite so many barnacles or other parasites attached to its body, so they have a smooth surface. Its top fin – the dorsal – is relatively small in relation to its sheer size and is located quite a long way back on the body. The Blue Whale also has short flippers in relation to its total body length. Also, as you would expect from such a large whale, when a blue whale exhales, the spray from its blowhole can reach nearly 30 ft (9m) into the air.
What Does a Blue Whale Eat & What Oceans Does it Inhabit?
The Blue Whale is almost totally dependent on krill. Krill are small, shrimp-like animals that grow up to about 6 cm in length and are typically found in dense swarms, often of more than 10,000 krill in each cubic square metre. The word krill is in fact a Norwegian phrase that actually means ‘Whale food.’ In the Southern Ocean krill are vital parts of the food chain, not just for Blue Whales and other whales, but the main diet for penguins, seals, squid and fish. A Blue Whale is estimated to eat as much as four tonnes of krill a day. Due to their dependence on one species for food, scientists fear the Blue Whale could suffer if the krill population is depleted by fishing or global warming.
Blue whales, though more plentiful in the Southern Hemisphere, can actually be found in all oceans of the world. In 2006, the Blue Whale was spotted in the Arctic Sea, Atlantic Ocean, Indian Ocean and Pacific Ocean, as well as the Antarctic Ocean.
The numbers of Blue Whales were severely depleted by commercial whaling, which only came to an end in 1986. The Blue Whale remains on the endangered species list.
Blue Whales and Communication
Research suggests that Blue Whales – typically solitary animals, though known to travel in pairs and congregate into larger groups at specific times to feed – can communicate with one another via calls across oceans. The Blue Whale can make sounds far below human hearing, at very low frequencies, which can travel hundreds of miles across the sea. In fact, scientists believe that the very-low-frequency courtship songs of Blue Whales are the most powerful biological sounds in the oceans. But the noise created by ships and other human activities could be interfering by drowning out whale calls when they are looking for a potential mate. Research suggests that whale songs evolved to take advantage of the ocean's sound channel, especially for some of their most important kinds of communication, including finding a mate. Interestingly, only male Blue Whales sing loud songs, suggesting a sexual reason for the calls, which are potentially being cancelled out by the din of modern shipping in the sea.
How Many Blue Whales Are There?
When whaling was at its peak in the early nineteenth century, the Blue Whale was safe from the Captain Ahabs of this world simply because they were far too big and far too fast to hunt in rowing boats with hand harpoons. But by the end of the nineteenth century and with the invention of the harpoon gun and steam ships, the size that had made them too much for earlier whalers, now made Blue Whales a major draw because of the amount of oil that could be extracted from a single whale. The slaughter peaked in 1931 when over 29,000 Blue Whales were killed in one season. Experts believe that as much as 99% of the entire Blue Whale population was killed through whaling until it was made illegal in 1986.
Though real figures are difficult to come by, especially for solitary Blue Whales, which show a reluctance to approach shipping, there are an estimated 5-10,000 Blue Whales in the Southern Hemisphere, and only around 3-4,000 in the Northern Hemisphere.
However, other figures highlight that there are less than 3,000 Blue Whales in the Southern Hemisphere. Some statistics show that the Blue Whale population is increasing slightly, though it is taking a long time to recover from the near-extinction that occurred in the early twentieth century through commercial whaling.