Subject: Diving

Martine Berube (martine@newt.bio.uci.edu)
Tue, 21 Oct 1997 18:26:31 -0700

Question: How do whales dive?

Answer: For small cetaceans, they use theirs flippers as hydrofoils to swim
down to dive and up to surface. For large whales, such as the fin whale,
they have relatively very small flippers, so they can dive by the action of
flexing the entire body. So if you look at a fin whale diving you first see
the snout, then the blowhole, then the back as the whale directs its head
down. The whale continue to flex its body and at the point when the flukes
are in deep water enough, with an upwardpower stroke, the whale disapears
under water. Some whales will show their tail at the surface (flukes) while
diving such as observed with the humpback whale. These dept of the dive
will depend on where the prey is concentrated.


Question: I am also curious about how whales sleep.  Is it true that some
whales sleep vertical with their heads down in the water and their tails up
in the air?

Answer: Whales sleep by shutting down half their brain at the time. So,
while one half
 is shutdown, the other half stays awake to monitor their breathing, body
etc.  From my experience with large whales (sperm, humpback), they sleep at
or just below the surface. They slow down their breathing quite a lot
something like one breath at the surface every 2-3 minutes.  They can sleep
for hours. I have never heard of whales sleeping in the position you
mentioned, maybe what you heard was relating to humpback whales on the
breeding ground, where they are observed singing in a similar upsidedown
position.

I hope this is of some help,
Martine

Martine Berube
Dept. of Ecology and Evolutionary Biology
University of California
Irvine, CA, 92697-2525
PHONE:714-824-8680
FAX:714-824-2181
E-mail: martine@newt.bio.uci.edu