Page 184 - Biomimetics: Technology Imitates Nature

Biomimetics: Technology Imitates Nature

Arctic Birds Using Counter-Current Heat Exchangers

In the coldest climates, local birds generally have
their feet either in cold water or standing on ice. Yet
there is no question of them ever freezing. All of them
possess circulatory systems that reduce heat loss to
a minimum. In these birds, heated and chilled
blood circulate in different blood vessels, but these
vessels run close together, however. In this way,
warm blood flowing to the extremities down-
wards warms the cold blood circulating up-
wards. This also reduces the shock of cold
blood returning to the body from the feet. This
natural heat exchange mechanism, known as
counter-current, is the same as that used in
various machines. 128

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