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The Big-Hearted Blue Whale

February 14, 2018

Not only are blue whales (Balaenoptera musculus) the largest animals in the sea, they are also the largest animals ever to live on this planet—even bigger than all known dinosaurs.


Not only are blue whales (Balaenoptera musculus) the largest animals in the sea, they are also the largest animals ever to live on this planet – even bigger than all known dinosaurs. Blue whales can grow to about 100 feet long, which is a little longer than a basketball court.

With all of that size, the blue whale needs a big heart. In fact, they have the biggest hearts on the planet. The heart of a blue whale weighs more than 1,000 pounds, the weight of an average dairy cow. A blue whale heart pumps about 60 gallons (7,680 ounces) of blood with each beat. In comparison, a human heart pumps merely 2.4 ounces with each beat. The aorta of a blue whale heart is so big that a human being could crawl through it!

The Blue Whale's Song

With all of that heart, and because it is Valentine’s Day, a love song had to be involved. Only male blue whales sing. Scientists believe their song is a mating call. Dr. Mark A. McDonald of WhaleAccoustics, in collaboration with Dr. John Hildebrand of the Scripps Institution of Oceanography and Dr. Sarah Mesnick of NOAA Fisheries Southwest Fisheries Science Center, suggested that blue whales have been singing at lowering frequencies over the past 50 years. Rivaling Barry White, their deep melodies are lower than the lowest note on an 88-key piano. The reason for the lower sounding whale song remains a mystery.

How Many Blue Whales Are There?

The current population of blue whales is about 10,000 to 25, 000 animals worldwide. Before whaling, about 300,000 blue whales populated our oceans, 240,000 in the Antarctic alone.

But don’t lose heart! A recent study on blue whale population trends was conducted by University of Washington Ph.D. student, Cole Monnahan (who is also a NOAA Fisheries/Sea Grant Fellow), and Professors Trevor Branch and Andre Punt. All three are part of the NOAA Fisheries QUEST Program. They found that blue whales are making quite a comeback in California. They believe the current California blue whale population is at about 97 percent of pre-whaling numbers, highlighting a heartening conservation success story. 

With at least 10, 000 individual animals worldwide, and growing, more than 10 million pounds of blue whale heart-beats are reverberating in the sea. And that is a whole lot of heart to consider on Valentine’s Day!

Last updated by Office of Science and Technology on July 26, 2021

Blue Whale