Blue Whale

The Blue Whale is the largest animal to ever exist on Earth.  The species currently lives in all oceans on Earth except the Arctic Ocean .

Blue Whale

Species Status: Endangered.

Blue Whales are the largest animals ever to have lived. They are bigger than the largest of the dinosaurs – the Sauropods, and they dwarf the African Bush Elephant – the largest land animal living on Earth today.  These very gentle creatures have very long, slender bodies that are bluish gray in color on their topside and a dappled grayish color underneath.  In some instances, the underside of a blue whale may appear yellowish.

They can weigh as much as 330,000 pounds (150,000 kg) and grow to over 100 feet (30 meters) long.  Newborn Blue Whales, called calves, are also the largest babies born of any animal on Earth. The newborn calf can weigh as much as 2,700 kilograms (nearly 6,000 pounds) and measure eight meters (26 feet) or more in length. Being that they are mammals, the calves are born live.

Think of the size of a giant commercial aircraft like the Boeing 747 jumbo jet… that’s how large they can grow! 

Because they are so large, Blue Whales eat literally tons of food. They are carnivores (meat eaters) which feed almost exclusively on small shrimp called krill.  Unlike most carnivores, they have no teeth; the Blue Whale’s mouth contains up to 800 long, slim plates of baleen (also called whale bone) with thick, coarse bristles that are used as a filtering system that catches the food they eat. An adult whale can eat as much as eight tons (7.25 tonnes) of krill a day!

Blue Whales can grow up to 100 feet (30 meters) long and weigh as much as 330,000 pounds (150,000 kg).

Blue Whales live in all oceans except for the Arctic Ocean.  They are largely solitary animals and are often found alone; still, they can be found in small groups in all oceans. Blue Whale populations are much larger in the Southern Hemisphere where they are more often found in groups. Due to its long lifespan, a blue whale can form an attachment to another blue whale that it spends time with.

Despite their size, Blue Whales can travel at relatively fast speeds.  They can move as fast as 20 miles per hour (32 kilometers per hour), although they normally move quite slowly.  They rarely breach — that is, jump into the air above the surface of the water like many other whales, thus limiting sightings of them to just at or beneath the surface of the water.

They can travel great distances from summer to winter to feed on the available food supplies. In the North Atlantic, for instance, Blue Whales will travel from the Greenland Sea in the summer and towards the equator in the winter; in the Pacific, Blue Whales will spend winters as far south as Central America and summers as far north as the Gulf of Alaska.  Blue Whales prefer to live in the deep ocean, thus making sightings near the shore very rare.


Blue Whales are endangered worldwide as listed by the International Union for Conservation of Nature  (IUCN) and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).  About 99% of the Blue Whale population was eradicated by commercial whaling in the late 19th and 20th centuries, sought for whale oil.  The pre-whaling population was estimated at about 350,000.   

Thanks to global bans on commercial whaling, including by the International Whaling Commission (IWC) in 1986, Blue Whale populations are making a gradual comeback.  Today their numbers are estimated to be as high as 25,000. Before global protections were provided, Blue Whales are estimated to have numbered less than 3,000.  Their only real threats today are vessel strikes and entanglements in fishing gear.  Whaling still occurs in countries such as Japan, Iceland, and Norway, however, described as being for scientific purposes; so, it is still a danger to these animals.

A Really BIG Heart

A Blue Whale female with her calf off the Ólafsvík Coast in western Iceland (Photo: Wikimedia Creative Commons 4.0 by Andreas Tille)

In telling of their very gentle nature, Blue Whales are known to have feelings and show affection.  This is primarily noted in the relationship between a female whale and her calf. When more than one Blue Whale is spotted, it will often be that of a female and calf which she nurtures until she gives birth to the next calf or when the calf reaches full biological maturity in about five to 15 years.

This caring nature of Blue Whales would indicate they have a big heart, figuratively speaking. But in reality, they actually have the biggest heart, biologically, of any animal on the planet!  The average size heart of an adult Blue Whale is about the size of an average pickup truck and weighs over 400 pounds.  Its heartbeat can be heard as far away as two miles (note that this is underwater), and their blood vessels are so large you could swim through them!

Topping off the list of the blue whale’s really big attributes are the sounds they make.  They are the loudest animal of all.  Because they emit sounds at such low frequencies, they can communicate with other Blue Whales as far away as 1,600 kilometers (995 miles) under the right conditions.

All told, there are so many things about Blue Whales to love and that are truly fascinating!

Blue Whale Fast Facts!

Size comparisons of Blue Whales to the largest of the dinosaurs (Sauropods), the extinct shark-like Megalodon, the largest living land animal on Earth today (African Bush Elephant) and humans. (Ecology Prime Data Resources)
  • Also Known as:  Sulfur-Bottom Whale (rare reference).
  • Types (subspecies):
    Northern Blue Whale – populations in the North Atlantic and Pacific Oceans and East Pacific.
    Northern Indian Ocean Blue Whale – resides year-round in the northwestern Indian Ocean.
    Antarctic Blue Whale – the largest and most populous of Blue Whales, resides in Antarctic waters.
    Pygmy Blue Whale – spread throughout the ocean regions from Madagascar and Indonesia to Australia and New Zealand.
    Chilean Blue Whale – considered a fifth subspecies by many scientists, they live off the Pacific coast of Chile and may overlap the region of the Antarctic Whale.
  • Class: Mammal. Warm-blooded and their calves are born live.
  • Order – Type: Carnivore (feeds almost exclusively on shrimp-like krill).
  • Color: Blue-gray with a light-gray spotted underside. Some individuals will have a yellowish underside, hence the nickname Sulfur-Bottom Whale.
  • Size (length): 80-100 feet | 24-30 meters.
  • Weight: Up to 330,00 pounds | 150,000 kg | 165 tons | 150 tonnes.
    Females are generally larger than males.
  • Range: All oceans except the Arctic Ocean.
  • Global Population: 10,000 to 25,000. The largest population is the Antarctic Blue Whale.
  • Life Span: 80-100 years in the wild. None are held in captivity, except for the occasional rehabilitation of calves.
  • Predators: No real natural predators – although rarely, Orcas (also known as Killer Whales) may prey on newborn calves. Their greatest threats today are shipping vessel strikes and entanglements in fishing gear.
  • Threat Status: Endangered.  All Blue Whales are listed as endangered by various organizations and protected by laws including the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), Endangered Species Act (US), and International Union for Conservation of Nature (IUCN). Commercial whaling was banned in 1986 by the International Whaling Commission (IWC).

Additional Readings about Blue Whales…