whale birth and reproduction (fwd)

From: Mike Williamson (pita@www1.wheelock.edu)
Date: Mon Apr 17 2000 - 17:05:14 EDT

From: "Phillip J. Clapham" <pclapham@whsun1.wh.whoi.edu>
To: PATRAPAN@aol.com, pita@whale.wheelock.edu, kburnett@whale.wheelock.edu
Cc: sherbet_starlight@yahoo.com
Subject: Re: whale birth and reproduction

Gestation time in large whales is generally around 11-12 months, except
sperm whales which are probably between 15-17 months. In dolphins and
porpoises it seems to average around 9-10 months. The growth rate of
baleen whale fetuses (e.g. blue, humpback whales etc) is the fastest of any
fetus in the animal kingdom, and is some twenty times faster than primates
like us. A blue whale fetus grows from a barely visible ovum at conception
to a 26 foot calf at birth in 11 months, which is an increase in tissue of
several billionfold!
There is debate about whether birth - which probably occurs rapidly in most
whales - is tail-first or head-first. Both have been observed, but we
don't know which way is the "norm".

Phil Clapham

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