10 Bountiful Blue Whale Facts
“Whale” is a common name for a variety of large marine mammals. The Latin word cetus gives the whale species its scientific title, Cetacea.
Whales come in two categories of Cetacea. The largest, Mysticeti, are characterized by sieve-like, baleen structures in their upper jaw that they use to filter food from the seawater. The other category, Odontoceti, have teeth, such as sperm whales and orcas.
Not surprisingly, blue whales fall within the large baleen parvorder of Mysticeti. Here are 10 of our favorite facts about this largest but little-seen whale species.
1. Blue Whales Are the Largest Animal Ever to Have Lived on Earth
Blue whales are the largest mammal to have ever lived on the Earth, growing to lengths of 30 meters (100 feet), or as long as three school buses. They can weigh as much as 200,000 kg (440,000 pounds), and several of their organs are the largest in the animal kingdom.
Blue whale hearts, for example, can weigh as much as a car, around 180 kg (400 pounds). However, they have proportionally small brains, about 7 kg (15 pounds), only .007% of its body weight. All blue whales are descended from land-living mammals and are thought to have begun their transition to seaborn life around 50 million years ago.
The low-gravity saltwater is why blue whales were able to grow larger than other animals.
2. The Blue of the Blue Whale Comes Partially from the Sea
Although blue whales are thought to have a deep blue color, when they are at the surface of the water they actually appear grey. When blue whales dive down again, the color of the water and the light from the sun make them look deeper blue than they really are.
Blue whales are really a lightly mottled blue-grey, with light grey or yellow-white undersides. The yellow ventral coloring is due to the accumulation of diatoms (microscopic unicellular marine algae) in cold water.
3. Each Blue Whale Has Its Own Unique Marking
Before modern whaling began in the late 19th century, little was known about blue whales. Nowadays, however, researchers have applied photo-identification to learn that the mottled pigmentation pattern characteristic of the species is unique to each individual.
The mottling is distinct enough that individual blue whales can easily be recognized through clear photographs. The amount of detail in the markings is so great that exact duplicates are extremely unlikely. Over a long period of study, researchers have learned about blue whale lifespans and migration routes.
4. Blue Whales Have One of the Loudest Voices on the Planet
Although we cannot hear them underwater, blue whales have one of the loudest voices on Earth. Their call can be louder than a jet engine, and has been measured at 188 decibels. It is thought that in good conditions blue whales can hear each other across distances of up to 1,600 km (994 miles).
Blue whales communicate by using loud, low-pitched moans and whines. During mating periods, around late autumn and until the end of winter, adult blue whales perform mating calls. These “mating songs” can likewise be heard over incredibly long distances.
5. Conscious Sleeping Means Maximum Blue Whale Efficiency
Although blue whales are mid-water hunters, they must come to the surface to breathe. Blue whales have twin blowholes shielded by a large splashguard. These blowholes are large enough for a young child to crawl through.
When blue whales surface, they exhale air out of their blowholes in a vertical cloud of pressurized vapor rising up to 9 meters high (30 feet).
When searching for food, blue whales sometimes dive very deep. The deepest confirmed dive was 506 meters (1,660 feet) with 35 minutes underwater. (Most dives last 10 – 20 minutes or less). Blue whales, like other whales and dolphins, are conscious breathers. They never fall asleep completely, resting only one half of their brain at a time. The other half stays awake to prevent drowning.
6. Big Blue Whales Survive on Small Things
Despite being Earth’s largest animal, blue whales primary eat krill, a small aquatic lifeform resembling shrimp. The Norwegian word “krill” means “young fry of fish.” Blue whales can eat as many as 40 million krill per day, or around (3,630 kg) 8,000 pounds daily.
In order to maintain their diet, blue whales are almost always found in areas with high concentrations of krill, such as the Arctic Ocean. Despite being such huge animals, blue whales lack the esophagus size to consume larger sources of food. They are unable to chew and break down food into smaller pieces.
In fact, the blue whale esophagus is so small it would not be able to swallow an adult human.
7. The Migration Patterns of Blue Whales Are Highly Diverse
Many whales, especially baleen whales, tend to migrate long distances between cold-water feeding grounds and warm-water breeding grounds each year. These migration patterns are not thoroughly understood and are highly diverse.
Some blue whales appear to be year-round residents of high-productivity habitats. Other blue whale groups migrate to cold water, like the Arctic and Antarctic, for feeding. As such, they are occasionally spotted on both Arctic cruises and Antarctic cruises.
After the end of feeding season, blue whales travel back to warmer water, where there are stable and secure places for birthing. On long migrations, blue whales are known to fast for up to four months, living off of stored body fat accumulated during their feeding season.
8. Even Baby Blue Whales Are Bigger Than Most Animals
Female blue whales breed only once every three years, and gestation lasts between 11 – 12 months. They usually have only one young.
Blue whale calves are born more than 7 meters long (25 feet) and weigh up to 3,000 kg (6,600 pounds). They enter the world already ranking among the planet’s largest creatures, and are suckled up to a year before feeding independently. Baby blue whales gorge on nothing but mother’s milk, gaining about 90 kg (200 pounds) per day during their first year.
9. A Built-In Thermal Insulator Keeps Blue Whales Warm
Heat loss in the water is 27 times greater than on land, but blue whales have adapted to cold oceans: More than a quarter of a blue whale’s body mass is blubber, which acts as a form of protection and thermal insulator.
Blue whales have no skin glands for evaporation, instead using blubber thickness and blood flow to stay warm.
10. Blue Whales Were Once Numerous
Blue whales have a truly global distribution, occurring in all of the world’s oceans. In pre-whaling eras, there may have been more than 250,000 blue whales worldwide. But intensive hunting in the 1900s reduced blue whale populations by more than 99 percent. From 1904 to 1967, more than 350,000 blue whales were killed in the Southern Hemisphere.
Fortunately, the 1966 International Whaling Commission finally gave them protection. Blue whales are one of the rarest whales, numbering between 10,000 – 25,000 today. Most biologists consider blue whales to be among the most endangered of the great whales.