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Marine Animal Encyclopedia

Blue Whale Balaenoptera musculus

The blue whale, one of the rorqual whales, is probably the largest animal that has ever lived. Its heart is the size of a small car and its call, at about 180 decibels, is louder than the sound of a jet aircraft taking off. This animal’s future hangs in the balance after decades of whaling. Although the blue whale is no longer hunted, it remains seriously endangered.

The blue whale has a flattened head, a pointed snout, and a pleated, expandable throat. The rest of the body tapers to a pair of enormous tail fins (flukes). Blue whales are a mottled blue mixed with gray on their backs, but their undersides vary from white to yellow. They feed by filtering small animals, mostly krill and other small crustaceans, from the water. Their baleen plates can collect over 6,600 lb (3,000 kg) of food a day. Females give birth to a single calf every 2–3 years.

The Blue Whale's Baleen

Instead of teeth, baleen whales have flexible strips of baleen, or whalebone, which hang from the upper jaw. To feed, the whale takes in a mouthful of water, then sieves it through its baleen. The water is expelled, leaving small animals trapped, which the whale then swallows.

Threats to Blue Whales

Blue whales feed exclusively on krill and require massive amounts to sustain their large size. Having been hunted to near extinction by historical whaling, blue whales now need krill to fuel their reproduction to recover their populations.

Krill fisheries, operating in the Southern Ocean and around Japan, harvest krill for human consumption and aquaculture feed. Increasing demand for new products, such as krill oil, may further reduce krill populations and stress blue whale survival.

What Oceana Does to Protect Blue Whales

Oceana works to promote responsible fishing, conservative catch limits and protected hotspots for predators such as blue whales. Ensuring that predators have enough food means protecting their prey from overfishing and conserving the ecosystem as a whole.

Blue Whalezoom image
Blue Whalezoom image
  • Order Cetacea
  • Length 80–90 ft (24–27 m)
  • Weight Up to 132 tons (120 metric tons)
  • Habitat Open ocean
  • Distribution Tropical, temperate, subpolar waters worldwide, except in regions with permanent sea ice
Blue Whale habitat mapzoom image