
Polo
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Whales sleep about 8 hours each day. Whales don't go into a deep sleep like we do, because they have to be partially conscious to breathe. Whales are able to partly sleep by letting one half of their brain sleep at a time. This is called unihemispherical sleeping.
http://www.enchantedlearning.com/subjects/whales/anatomy/Sleep.shtml
When they dive, their heart beats more slowly and select arteries are constricted. This slows the flow of blood to certain organs without decreasing blood pressure.
http://science.howstuffworks.com/whale.htm/printable |