Subject: Re: Blue Whale - mainly bones

Greg Early (gearly@neaq.org)
Fri, 06 Nov 1998 14:09:37 -0500

At 08:23 PM 10/21/98 -0600, you wrote:
>Dear  Greg Early,
>
>I am David Packman, a fifth grader from Bear Creek Elementary School in
>Boulder,
>Colorado. I have several questions about the Blue Whale. Here are some:
>
>What is the bone structure of a blue whale [ed. note: what does the
>skeleton look like]?
>
>What can we tell from this structure such as:
>   What is the difference in bone structure between male and female?
>   What does the fossil record of bone structure tell us about whale
>locomotion?
>        [ed. note: evolution from land? Any tendon markings on fossils
>to indicate
>         underlying muscle structure?]
>    Any evolutionary evidence for a change in whale diet?
>    How do they sleep? [eg, posiition, duration, time of day]
>
>Thanks for considering these questions.
>David Packman
>pack@ucar.edu
>


David,

Sorry this took so long, but you have quite a list, here, and some very
good questions.

1.)  A whale skeleton looks quite unlike most other skeletons (one of the
earliest fossil whales was mis identified when it was first found, the
folks that found it thought it was a giant reptile).  The parts you would
recognize are the front flippers, that look a bit like short arms with huge
hands attached.  A whale's backbone looks a little like other mammals,
however they have more vertebrae than most mammals (all of those are added
to the tail end of the backbone).  Whales have little squashed neck
vertebrae (seven bones...cervical vertebrae...just like you and me and
dogs, cats etc...but theirs are so short and flattened that they can not
move their "neck").  Their skull looks like no ther mammal with a long bone
where your lip would be, their nose on the top of their head and eyes
around the side of their jaw.

2.) Fossil record on whales is not great, but there are some ancestors of
modern whales that have tiny legs.  Something modern whales lack.  We
figure that whales evolved from the ancient Tethys sea in an area that is
around the Persian Gulf these days.  That sea was a warm shallow sea with
gradually sloping shores.  Scientists think that as the Tethys sea expanded
over millions of years the whales moved from the coast to the open ocean.
Whales probably left the shore about 150 million years ago.

3.)  This one beats me.  We generally think that whales started eating
small fish along the shores and gradually evolved baleen to take advantage
of schooling fish and invertebrates, but most of that is guesswork I suspect.

4.)  You would think we would know this one, but we don't for sure.  Marine
mammals have to keep breathing to some extent or they will drown so they
can not go for too long without getting to the surface to breath.  You
would think that you could sneak out at night and catch all of the whales
sleeping on the surface, except this does not happen.  Dolphins and small
whales in Aquariums spent time quietly on the surface and either on the
bottom or hanging in the water during the night, but they do not appear to
be deeply asleep.  Some scientists think that whales and dolphins take
short naps...and some think dolphins can have half of their brain asleep
while the other half stays awake.  (sort of like me first thing in the
morning).  Basically we do not know for sure.

Regards,

ge


Greg Early
Edgerton Research Laboratory				
New England Aquarium
Central Wharf
Boston, Mass 02110
617-973-5246 (phone)
617-723-6207 (FAX)		
gearly@neaq.org