[chris (OP)]

Someone told me today that marine mammals like whales and dolphins can sleep with one eye open. This means that half of their brain can be in sleep whilst half remains active. This helps to prevent drowning by falling asleep underwater, I was informed.

Is this the case and does anyone know more about this?

Chris

[atrox]

Hello chris!

Yes, your informant was right!
Indeed, only one half of the brain of dolphins, other wales, manatees and even some birds (like the swift (Apus apus), which sleeps during flying) sleeps at one time.
Scientists discovered this sleeping-technique in the 70s already. Both Hemispheres alternate about every 2 hours. The one, thats awake controlls in some kind of a coma or doze, if there are enemys or barricades and takes care of breathing on time, so the other one can rest. The Eye of the side of the wake Hemisphere is closed (because the right Hemisphere controlls the left bodyside and the other way around).
Dolphins sleep about 1/3 of a day.

bye
aj

[chris (OP)]

Hello chris!

The Eye of the side of the wake Hemisphere is closed (because the right Hemisphere controlls the left bodyside and the other way around).
aj

Hmm, but the visual scene on each side of the body is assembled using inputs from both eyes. This would limit the amount of vision in the awake hemisphere. Or is marine cetacean vision entirely crossed (no uncrossed fibres as is the case in humans) ?

Chris