How do orcas sleep

From: HG (
Date: Mon Nov 26 2001 - 19:22:27 EST

>Dear Howard:
>I know that bottlenose dolphins shut down half of their brains while
>sleeping, along with the opposite eye. And that the other half of their
>brain stays awake a a low level of alertness.
>What about other cetaceans? Do orcas also follow this pattern? Baleen
>whales? I assume all mother whales must do this, so that they can keep
>swimming and keep their calves blowholes above water, at least some of the
>Sue Rosenthal

         Every indication I've ever seen says the orcas, like other
dolphins, do shut down half of the brains when resting. I haven't seen
anything published that shows that baleen whales also follow that pattern,
but it stands to reason that they do, because all cetaceans are voluntary
breathers and must carefully time each breath with their surfacing. Yes, I
presume mother whales do this. The amazing thing is that newborns must be
capable of hemispheric brain control at a very early age, probably within a
few minutes.

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