How It Works - UK (2020-02)

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ANIMALS

Deep-sea stethoscope listens

to a blue whale’s heartbeat

Words by Brandon Specktor

W

hen the largest animals on Earth

grab a snack, their hearts skip a beat

• or 30. That’s what a team of marine
  biologists found after recording a blue
  whale’s heartbeat for the first time ever. After
  suction-cupping a pulse monitor to the back
  of a blue whale off the California coast, the
  researchers watched as the gargantuan
  creature dove and resurfaced nonstop for
  nearly nine hours, alternately filling its lungs
  with air and its belly with schools of fish.
  During these deep, grub-hunting dives, the
  whale’s heart rate fluctuated wildly, pumping

as many as 34 times per minute at the surface

and as few as just two beats per minute at the

deepest depths – about 30 to 50 per cent

slower than the researchers expected.

According to a recent study, the simple act

of catching a bite may push a blue whale’s

heart to its physical limits. “Animals that are

operating at physiological extremes can help

us understand biological limits to size,” lead

study author Jeremy Goldbogen, an assistant

professor at Stanford University in California,

said in a statement. This natural cardiac limit

may explain why blue whales max out at a

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certain size, and why there have never been

any known animals on Earth any larger.

Because a bigger creature would require even

more oxygen to sustain its long deep dives for

sustenance, its heart would need to beat even

faster than a blue whale’s to refuel its body

with oxygen at the surface.

According to the study authors, that doesn’t

seem possible based on the current data; blue

whales may have – now and forever – the

hardest-working hearts on Earth.

The world’s largest animal can

survive on just two heartbeats

per minute