Why are whales (the blue whale) so large?

From: Peter M Scheifele (acousticp2@juno.com)
Date: Wed Dec 06 2000 - 22:20:43 EST


 why do some whales grow to be so large? In other words, is
> there anything special about being a marine mammal that enables it
> to be the largest creature on earth?

Part 2 of this question is -
> do blue whales have any special adaptations that enable them to be
> so large? For example, I think that I read somewhere that their
> neck bones are fused together to hold up their enormous weight - are
> there other adaptations like this?

Sara
Its more like the marine environment allows an animal, such as the Blue
Whale, to grow large. This is primarily because of the buoyancy aspect.
The water will support a large-bodied animal whereas on land the skeletal
structure must totally support the body. In the latter case, gravity
doesn't allow such large form to be so functional. The structure of
cetaceans in general, reflects a completely aqautic mode of life. The
body is fusiform (cigar-shaped). Most vertebrae have high neural spines
and the cervical vertebrae are highly compressed. Little movement is
possible between the joints surrounding the shoulders. In other words,
the support is from the environment and the phylum and specific species
have adapted to it.

>From an evolutionary standpoint, a terrestrial animal that became aquatic
might grow large and as it browsed in shallow seas, could maintain enough
of a food supply to support such a large body mass. Some archeocetes grew
to large sizes. We know this based on fossil sizes. In colder waters it
would also adapt to a large sizeas the result of gaining the blubber
sheath in an effort to maintain homeostasis. Large size also allows them
to fast during calving times (when they esentially don't eat!). Large
size allows for deeper dive capability without suffering diving
(decompresssion) problems such as the "bends."

This is a round-about answer, I know but when I return to my office at
the university on Friday I'll check the latest text I'm using with my
colleagues. I'm the bioacoustician s I tend to deal with ears, head and
neck more. By-the-by, for ny future inquiries my e-mail the UConn is
<scheifel@uconnvm.uconn.edu> as well as this address. Either will get
me.

Peter M."Skip" Scheifele LCDR USN (Ret.)
Director of Bioacoustic Research, University of Connecticut NURC NA&GL
(Voice) 860-405-9103/9121; acousticp2@juno.com;
scheifel@uconnvm.uconn.edu
www.nurc.uconn.edu
http://ap.nurc.uconn.edu/cos/



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