It is Marine Megavertebrate Week right now, so why not take a look at one of the most Mega of the Megaverts - the grey whale (Eschrichtius robustus):
Do whales sleep? You may have heard that dolphins do - one hemisphere at the time, while swimming, and not for very long periods at a time. A combined Russian/US team of researchers published a study in 2000 - to my knowledge the best to date - on sleep-wake and activity patterns of the grey whale: Rest and activity states in a gray whale (pdf) by Lyamin, Manger, Mukhametov, Siegel and Shpak.
The whale in the experiment rested in two different ways: either resting on the bottom of the pool, or "hanging" just below the surface with the blowhole being the only part of the body above water.
What they found is that the whale is a diurnal animal - awake and active during the day, while resting and sleeping during the night.
Furthermore, the whale sometimes slept with both eyes open, sometimes with one eye open (like a dolphin or a duck, indicating that one brain hemisphere is asleep and other one awake), and sometimes with both eyes closed.
Ocasional full-body twitches were observed during sleep, often accompanied by rapid movements of the eyes, suggesting that these were episodes of REM sleep. Similar twitches occur in a couple of species of dolphins that were studied before, as well as beluga whales. The beluga whales are also he only other species to be observed to rest on the bottom of the pool.
Nobody knows, of course, what the whales do in the wild. But even studying them in captivity is not an easy kind of research to do, for both technical and regulatory/ethical reasons, so the fact that these papers do not have as much data as your run-of-the-mill rat paper does not, in my mind, detract anything from their importance. Moreover, comparative analysis is neccessary for the understanding of the origin, evolution, ecology and function of sleep - something long neglected by generally anthropocentric sleep research. And we know that, contra Michael Egnor, there can be no medicine without evolution.
Comments
I swam with 2 Sperm Whales who came into a small bay in the North Island where I lived, at a certain time of year for 3 days every year for 6 years.
They where almost beaching in the shallows. Each interaction lasted 2-3 hours. It took me 4 years to get alongside the female who accepted me touching her. The male always moved off 10ft from me when I tried to go near him. But came back alongside the female when I moved back over to her otherside.
They usally in a "foul" mood too! I've been zapped with the stun sonar once for poking her awake (fair enough!), and jaw snapped at! (a wave bumped me into her).I must be annoying, but they never moved away from me, where as they'll compelety leave if anyone came near in boat or in the surf.
They had appeared to be recovering from deep dives. They radiated cold from they bodies and were very slow in movement and breathing. I think they may have been decompressing (?). The female would take "cat naps" half closing her eyes or sometimes fully closing her eyes. Full closed eyes sleep, lasted up to one hour, before shifting out further to avoid beaching.
I think that because of the deep dive they were decompressing, and like divers with the bends, they are afraid they will passout and drown if out in deep seas. Maybe some do, and thats how they end up beaching entirley and dying, unable to come round to shift out deeper.I think the sperm whale in Japan which sank the boat was doing this same behaviour as I've witnessed, except he got harrssed (like I said, they're usally in a foul mood). Swam out of the bay ok. Deep sleep is/must a part of their recover period (?). Looking at the number of whales getting hit by ships suggest that perhaps they do the rest on the surface sleep, and do have a "total shut down" deep sleep. Unknown is how long the sleep period is when out at sea. Perhaps the same or longer than 2 hours?
Posted by: Leisa | April 20, 2007 8:35 AM
hey, that's a nice experience to be able to gain the whales trust =)
Posted by: Berni | October 14, 2007 7:51 AM
How do whales breathe if they are asleep on the bottom?
Thanks
Joanne
Posted by: joanne jansen | October 16, 2007 12:20 PM
They can go for a couple of hours between breaths.
Posted by: coturnix | October 16, 2007 12:41 PM
How do whales who rest and/or sleep on the bottom near the shore not crash their own organs by their weight?
Posted by: Britt | November 14, 2007 8:09 PM
I REALLY NEED MORE INFORMATION ON WHALES SO WRITE ME MORE INFORMATION ABOUT HOW WHALES SLEEP
Posted by: TAMIA | January 23, 2009 8:11 PM
This is what I know. You can certainly find more by yourself.
Posted by: Coturnix | January 24, 2009 3:34 PM