  Characterisations of the long-term behaviour of heart rate variability in
humans have emerged in the last few years as promising candidates to became
clinically significant tools. We present two different statistical analyses of
long time recordings of the heart rate variation in the Eastern Oyster. The
circulatory system of this marine mollusk has important anatomical and
physiological dissimilitudes in comparison to that of humans and it is exposed
to dramatically different environmental influences. Our results resemble those
previously obtained in humans. This suggests that in spite of the
discrepancies, the mechanisms of long--term cardiac control on both systems
share a common underlying dynamic.
