Subject: Heart Rates

Michael Williamson (pita@whale.simmons.edu)
Tue, 22 Oct 1996 18:35:44 -0400 (EDT)

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---------- Forwarded message ----------
Date: 18 Oct 96 14:06 EST
From: CLAPHAM.PHIL@SIMNH.SI.EDU
To: "G.ask [Private Mail Group]"@SIMNH.SI.EDU,
    "GCLARKE@MAGNA.COM.AU"@SIVM.SI.EDU
Subject: Copy of: QUESTION

Original message: "QUESTION"
From: <<gclarke@magna.com.au>>

Dear Sir,

At what rate does a whale's heart beat?

Thanks,
Graham.

Hi:

  To my knowledge, no one has ever successfully obtained a heart rate
from a free-swimming, unstressed large whale, although a prominent
Colombian cardiologist named Jorge Reynolds has attempted this for
some years and may have succeeded recently.

  Here's what we know, however.  First, the general principle is that
the larger an animal is, the slower its heart beats.  Thus a mouse
typically has a heart rate of about 650 beats a minute.  Allometric
(= scaling) calculations suggest that a large whale should have a
heartbeat at rest of around 8 a minute.  In 1959, a fin whale which
had stranded on Cape Cod was determined to have a heartbeat of
25 a minute, and from other work we know that stranded animals - which
are very stressed because of the crush of their own weight out
of water - have a heart rate about 3 times the normal.  So it seems
likely that about 8 beats a minute is accurate.

  Incidentally, the heart of a large blue whale is astonishingly large.
Well, in terms of its RELATIVE size (compared to the animal's mass),
it isn't: it's something less than 1% of the animal's body size, which
is not dissimilar to the equivalent size in humans.  But in absolute
terms... it is the size of an automobile!

  Phil Clapham