Blue Whale

Blue Whale
Source:, Photographer: Denis Scott/Corbis

The Blue Whale is a marine mammal belonging to the baleen whales, and is the largest creature ever known to have lived on earth. In fact, they may attain a length of as much as 98 ft (30 m) and weigh as much as 380,000 lbs (172,365 kg)!

Long and slender, the body of the Blue Whale can be various shades of bluish-grey dorsally and somewhat lighter underneath. There are at least three distinct subspecies, in several oceans:

  • B. m. musculus of the North Atlantic and North Pacific,
  • B. m. intermedia of the Southern Ocean and
  • B. m. brevicauda (also known as the pygmy blue whale) in the Indian Ocean and South Pacific Ocean

The Blue Whale has a long tapering body that appears stretched in comparison with the stockier build of other whales. The head is flat, U-shaped and has a prominent ridge running from the blowhole to the top of the upper lip. The front part of their mouth is thick with baleen plates; around 300 plates hang from the upper jaw, running approximately 1.6 ft (0.5 m) back into the mouth.

Between 70 and 118 grooves (ventral pleats) run along the throat parallel to the body length. When surfacing to breathe, the blue whale raises its shoulder and blowhole out of the water to a greater extent than other large whales, such as the fin or sei whales.

The Blue Whale has a lung capacity of 1,320 gallons (5,000 liters).

Some blue whales in the northern parts of the Atlantic and Pacific raise their tail fluke when diving.


Blue Whale
Source: Photographer: Matthew Coutts

Blue Whale Description and Behavior

When breathing, the whale emits copious quantities of water. The species have twin blowholes shielded by a large splash guard.

The upper sides of their body is grey with a thin white border; the lower sides are white. The head and tail fluke are generally uniformly grey and the upper parts, and sometimes the flippers, are usually mottled.

The degree of mottling varies substantially from individual to individual. Some may have a uniform slate-grey color, but others demonstrate a considerable variation of dark blues, grays and blacks, all tightly mottled.

Blue whales can reach speeds of  as much as 31 mph (50 kph) over short bursts, usually when interacting with other whales, but 12 mph (20 kph) is a more typical traveling speed. When feeding, they slow down to about 3 mph (5 kph).

Blue whales most commonly live alone or with one other individual. It is still unclear to humans how long traveling pairs stay together.


Blue Whale

Blue Whale Feeding Habits

In locations with a high concentration of food, people have seen as many as 50 blue whales within a small area. They do not form the large, close-knit groups seen in other baleen species.

Blue whales feed almost exclusively on krill, though they also take small numbers of copepods. An adult blue whale can eat up to 40 million krill in a day! The whales always feed in the areas with the highest concentration of krill, sometimes eating up to 7,900 lbs (3,600 kg) of krill in a single day. Therefore, protection of krill is vital to the existence of blue whales.

The whale feeds by lunging forward at groups of krill, taking the animals and a large quantity of water into its mouth. The water is then squeezed out through the baleen plates by pressure from the ventral pouch and tongue.

Once the mouth is clear of water, the remaining krill, unable to pass through the plates, goes into the stomach. The blue whale also incidentally consumes small fish, crustaceans and squid caught up with krill.

Check out our articles on Beluga Whale, Right Whale, Ocean Conservation, Whale SharkGray Whale, Narwhal

Todd Sain Sr.