Blue Whale

Blue Whale Classification and Evolution

The Blue Whale is an enormous species of whale that is found in subtropical and polar waters worldwide. With some individuals growing to more than 100ft long, the Blue Whale is not only the largest animal species in the world but it is also thought that it could be the biggest creature that has ever existed. There are three recognised sub-species of the Blue Whale which are the Northern Blue Whale, the Southern Blue Whale and the Pygmy Blue Whale that despite its name, still reaches an average length of 24 meters. Although their enormous size and slow-maturing nature has meant that the world’s Blue Whale population has never been greatly numerous, they have drastically declined in numbers due to having been hunted by Humans particularly over the past 100 years. Blue Whales are now legally protected and despite one not having been deliberately caught since the 1970s, their numbers are continuing to fall in much of their natural range.

Blue Whale Anatomy and Appearance

The Blue Whale has an enormously long body that is slim and narrow, which means that they are able to cut through the water with ease. Their hairless skin is smooth and greyish blue in colour with a lighter underside and a series of pleats on their throats which allows it to expand to more than four times its normal size when the Blue Whale is feeding. The large tail of the Blue Whale is straight and splits into two rubbery flukes at the end and helps to propel their massive bodies through the water. Blue Whales belong to the “Baleen Whales” group which means that instead of having teeth, there are up to 395 hard and bristle-like baleen plates that hang from the upper jaw and are used to filter food out of the water. Like their relatives, Blue Whales also have two blow-holes on the top of their large heads which are used to expel stale air and sea water from their lungs when the Blue Whale surfaces to breathe.

Blue Whale Distribution and Habitat

Blue Whales are found in both polar and tropical waters worldwide, migrating between the two at different times of year. In the summer months, Blue Whales are found in the cold waters of the Arctic and the Antarctic (depending on the sub-species) where they feed on the abundant amount food, before moving towards warmer, less-rich waters for the winter when they breed. Although the three Blue Whale sub-species do differ slightly in size and colouration, the main difference between them is where they live with Northern Blue Whales and Southern Blue Whales never meeting one another. Northern Blue Whales tend to inhabit the rich, vast waters of the North Atlantic and North Pacific Oceans, where Southern Blue Whales are found on the other side of the Equator in the southern hemisphere. Although Pygmy Blue Whales are also found in the south, they tend to prefer the southern Indian Ocean along with the South Pacific.

Blue Whale Behaviour and Lifestyle

With the exception of females with their young, Blue Whales are solitary animals that are known to occasionally gather in loose groups to feed. These enormous animals use a variety of sounds (known as songs) including hums, squeaks and rumbles to communicate between one another, particularly during the breeding season in winter. In order to ensure that their voices are heard, the noises Blue Whales make are incredibly loud and having been recorded at volumes greater than 180 decibels, they are known produce the loudest sound of any creature on the planet. The Blue Whale has very small fins and flippers so relies on its enormous tail to help it to plough through the ocean. Blue Whales also uses their tails to make deep dives as by bringing it above the surface of the water, they are able to get enough power to travel up to 200 meters steeply down into the sea.

Blue Whale Reproduction and Life Cycles

Blue Whales breed in the warmer, tropical waters during the winter or early spring when after a gestation period that lasts for nearly a year, the female Blue Whale gives birth to a single calf on her return to the region the following year. After spending all summer feeding in the cold, rich waters at the poles, female Blue Whales eat almost nothing whilst they are nursing their young. Newborn Blue Whales already measure seven meters in length and weigh around 2.5 tonnes and remain by their mother’s side for at least their first year. Before they are weaned by the time they are eight months old, Blue Whale calves are known to consume up to 90kg of milk every day. Blue Whales are able to start reproducing themselves when they are between 10 and 15 years old with females giving birth every two or three years. Blue Whales can live for up to 40 years.

Blue Whale Diet and Prey

The Blue Whale is a carnivorous animal that despite the fact that it doesn’t have proper teeth, survives on a diet that is mainly comprised of krill and small crustaceans, along with the occasional small fish. Blue Whales feed by swimming up towards a shoal of prey and thanks to the pleats on their neck which allows their throat to expand, take an enormous gulp of water into the sac created in their lower jaw and shut their mouths. The water is then expelled but thousands of tiny creatures are retained by their fine baleen plates which are then swallowed. Blue Whales are able to consume up to six tonnes of prey every day during the summer months which they spend in the cold, rich waters around the poles. Although Blue Whales are known to eat a tremendous amount during the summer, when they migrate to the warmer waters for winter to breed they will barely eat anything at all.

Blue Whale Predators and Threats

Due to the immense size of an adult Blue Whale, they have no natural predators in the ocean with people being their biggest threat. Young Blue Whale calves however, are more vulnerable particularly once they have left the safer, warmer waters of their nursery and begin to travel throughout the more dangerous seas. Blue Whale calves are preyed upon by pods of Killer Whales that are able to use their intelligence and team work to catch and kill such a large animal. However, when Blue Whale hunting began in the 1800s with the invention of a more technical harpoon the biggest trouble for Blue Whales began. With increasingly better technologies, the situation escalated in the 1900s and decimated the global Blue Whale population, with people hunting them for their meat and blubber until an international ban finally gave them some protection in the 1960s.

Blue Whale Interesting Facts and Features

The Blue Whale is the largest animal on the planet meaning that numerous organs are much, much bigger than those found in any other animal. Apparently just one breath from a fully grown adult Blue Whale, will produce enough air to fill nearly 2,000 balloons! Also, the heart of the Blue Whale is so big that it is around the same size as a small car, with their main arteries being big enough for a human to swim through comfortably! Being mammals, Blue Whales must come to the surface to breathe in air but also have to expel it and do so by blowing all of the warm, humid air, mucus and sea-water out of their lungs through their two blow-holes and into the air. Blue Whales do this with such force that this column can shoot as high as nine meters into the sky.

Blue Whale Relationship with Humans

Historically, people would not have been able to hunt Blue Whales as they simply had no means to do it, eating the meat and using the fatty blubber to produce oil from those individuals that either became beached or were washed ashore. With better boats and tools for hunting, the catching of Blue Whales began in the North Atlantic in 1868 and had spread around the world but the turn of the century. In 1966, Blue Whales were protected from hunting after population numbers fell drastically around the world and there has not been a Blue Whale deliberately caught since 1978 off the coast of Spain. Today, people greatly admire these gentle giants with whale-watching trips being popular around the world.

Blue Whale Conservation Status and Life Today

Today, the Blue Whale is listed by the IUCN as an animal that is Endangered in its oceanic environment with less than 20,000 individuals thought be left around the world. A hundred years ago it is estimated that the Blue Whale population was significantly higher at roughly 200,000 but numbers were obliterated due to hunting. Blue Whale populations today are thought to face no major threats with the effects of global warming melting the ice-sheets at the poles thought to be of the biggest concern. Although they are no longer hunted (and populations in some areas are thought to actually be increasing), Blue Whales are threatened by accidents with ships.