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What is a Blue Whale?

A blue whale is a marine marvel, the largest animal to have ever existed on Earth, eclipsing even the mightiest dinosaurs. These gentle giants roam the ocean's vastness, their heart the size of a small car, their song capable of traveling hundreds of miles underwater. Imagine what secrets they could share about the deep blue sea. What wonders might they reveal?
S. Mithra
S. Mithra

The endangered blue whale has achieved the position of the single largest organism ever to live on Earth. Blue whales have baleen plates instead of teeth, migrate long distances, and communicate through vocalizations. Whaling during the early 20th century all but wiped out this magnificent animal.

As a mammal, a blue whale must breathe air, stay warm, and give birth to live young. It breathes through two blowholes at the top of its head, and usually a single breath lasts 15 minutes. Since blue whales are found in every major ocean, they migrate to follow the temperate current. During winter, they swim around the subtropical or temperate regions closer to the equator, but for summer they travel long distances to reach the cooler arctic regions.

Blue whales are the largest organisms ever to live on Earth.
Blue whales are the largest organisms ever to live on Earth.

The blue whale, or Balaenoptera, stretches an incredible 70-80 ft (21-24 m) on average, and weighs 90-150 tons (82-136 metric tons). These giant creatures need about 4 tons (3.6 metric tons) of krill, a type of shrimp, per day. They feed by filtering water through their baleen plates, catching tiny bits of food. If not caught in fishing nets, illegally harpooned by whalers, or adversely affected by pollution, a blue whale should live from 40-80 years.

The three species of blue whale look similar. The musculus lives in Northern oceans, the in the tropical zones, and the intermedia further down in the Southern hemisphere. They are bluish grey with wide tail flaps, called flukes. The splotches on their backs are so unique that they've been used by marine biologists to identify individuals. Those ridges along their neck that stretch from their chin to their stomach are called rorqual, for the Norwegian word for "furrows."

A blue whale breeds during the winter, every 2-3 years, while it fasts and lives on accumulated fat. After a gestation period of a year, a female will give birth to one calf that nurses for 6 months to a year. Gradually, the calf will transition to eating krill, but will probably stay with its mother for a couple of years for protection. It will reach sexual maturity when its 5-7 years old.

Sadly, the large populations of whales have dwindled in the last century due to new technology that made killing them easier for whalers. Along with pollution and other threats from mislaid fishing nets, the number of blue whales has plummeted to a few thousand. Many efforts, including limited whaling and regulated fishing, work to keep this whale from extinction.

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Discussion Comments


The blue whale is known to be among the loudest animals on earth. Their sounds can often be heard up to 1,000 miles. Their average speed is about 10 mph but can swim up to 30 mph, especially when spooked.

When the blue whales spray, it can reach up to 30 feet in the air. The oldest known blue whale lived to be 110 years old.

When a blue whale gives birth, the calf is born at an astonishing 25 feet long and weighs about 3 tons. The calves consume about 100 gallons of mother’s milk a day. The milk of the blue whale is rich in fat and the calves generally gain about 200 pounds per day. That is about 8 pounds an hour!


@medicchristy: Humans haven’t always been a threat to the blue whale. Before the 20th century, they were really no threat at all. In the 1920’s, after the exploding harpoon gun and the factory ships were introduced, humans went on a killing spree with the blue whales that almost caused them to become extinct. Before their protection in 1966 by the International Whaling Commission, over 360,000 blue whales were killed.

Today, they are on the endangered species list. It has been estimated that only around 15,000 blue whales remain.


Why are humans a threat to the blue whale?

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    • Blue whales are the largest organisms ever to live on Earth.
      By: Tlaloc Xicotencatl
      Blue whales are the largest organisms ever to live on Earth.