As the largest animals ever known to have lived on earth, the blue whale is a magnificent species that can be found all over the world. 

Fast Facts

Common name: Blue whale

Scientific name: Balaenoptera musculus

Type: Mammal

Diet: Carnivore

Group name: Pod

Average weight: Approximately 150 tonnes

Average length: 25 to 30 metres

COSEWIC Status: Endangered

Did you know?

Blue whales were hunted to near extinction during the 20th century. They are still endangered, but are now protected by international hunting bans.

Physical characteristics and behaviour

Blue whales are big mammals — everyone knows that. But scientists say they are likely the biggest animals that have ever lived on Earth — even bigger than the largest dinosaurs. How big is that? Well, blue whales typically reach lengths of 25 to 30 metres, longer than most swimming pools. They can also weigh up to 200 tonnes, which is heavier than most houses. Blue whale calves are born already measuring seven metres in length, and weighing two tonnes!

Blue whales aren’t actually blue — they’re grey. They just appear blue under water. Their underbellies have a yellowish hue, from the millions of microorganisms that take up residence in their skin. Blue whales have broad, flat heads and long, tapered bodies that end in wide, triangular flukes. 

Blue whales are noisy creatures. Their calls can reach volumes louder than a jet engine. They emit pulses, groans and moans which, under the right conditions, can reach other blue whales over 1,500 kilometres away. Scientists believe that these calls are used not only to communicate, but also to sonar-navigate the dark ocean depths.

Diet

As big as blue whales are, they feed exclusively on tiny crustaceans called krill. The whales have to eat a lot of krill — up to four tonnes a day. To catch this food source, the whale charges into a school of krill, opens its mouth and takes in a massive amount of water. The whale then expels the water through its baleen, a kind of filter attached to its upper jaw that catches the krill for the whale to swallow.

Habitat and distribution

Blue whales have habitat all over the world. The Northwest Atlantic blue whale population is usually found in the Gulf of St. Lawrence and off the coasts of Nova Scotia and Newfoundland. Blue whales are also seen off Canada’s West Coast.