Subject: circulatory systems

Howard Garrett (
Mon, 3 May 1999 18:57:49 -0400 (EDT)

I am doing research for school on Blue Whales.   A few questions:

1.  Do they have opened or closed circulatory systems, do they have closed
or open blood vessels?

        I'm not familiar with the terms "open and closed blood vessels"
except as applied to the next question.

2.  How does it maintain homeostatis

        .By this I assume you are referring to whales' thermoregulation
systems, by which they are able to regulate their inner body temperatures.
By opening, or dilating, blood arteries near the skin surface, especially in
their extremeties (tails, dorsal fins and flippers), they are able to
disipate heat into the water, thus cooling themselves when they overheat due
to energetic physical activity. Conversely, when they need to conserve their
body heat, they narrow their arteries in those areas to minimize the loss of
heat, and shunt warm blood to arteries surrounding veins carrying blood back
to the heart, thus holding heat inside the body. This applies to all whales.
Some whales, such as right whales, cool their bodies additionally by opening
their massive mouths and flushing cool water close to their "rete
mirabilia," which is a dense system of blood vessels near the roof of their
mouths, to cool their bodies.

Howard Garrett
Tokitae Foundation
Lolita Campaign Coordinator
(305) 672-4039

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