Blue Whale

Blue Whale

Source:, Photographer: Denis Scott/Corbis

The Blue Whale is a marine mammal belonging to the baleen whales, and and is the largest creature ever known to have lived on earth. 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


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 (called 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 North Atlantic and North 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. Blue Whales have twin blowholes shielded by a large splashguard. 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. The whale’s 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, greys 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 not known how long traveling pairs stay together.


Blue Whale


Blue Whale Feeding Habits

In locations where there is a high concentration of food, as many as 50 blue whales have been seen scattered over 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.

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, are swallowed. The blue whale also incidentally consumes small fish, crustaceans and squid caught up with krill.


Todd Sain Sr.

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