Subject: Copy of: WHALES SUCKLING

Michael Williamson (CLAPHAM.PHIL@SIMNH.SI.EDU)
14 Oct 96 10:26 EST

Original message: "WHALES SUCKLING"
From: <<zimpress@zim.co.il>>

Hello

The son of a friend came up with this question, which I hope you can
answer. How do whale calves suckle their mother's milk ? it seems like a
technical difficulty. Is it as simple as suckling on land ?

Thanks
Avner@zimpress

Hi:

Actually, that's a great question and it's not one that we know everything
about.  The mammary glands of a female whale are located on either side of
the genital slit, which is on the underside of the animal back towards
the tail.  A major difference between whales and land mammals is that
the former's mammary glands contain what are called compressor muscles,
which the mother uses to actively pump milk into the mouth of the calf
(i.e. it' isn't passive, with the kid doing most of the work by suckling).
This undoubtedly evolved as a means of getting around the obvious problems
you're thinking of, concerning suckling in an aquatic environment.

As for the posture: there is a gap between the two racks of baleen in
the mouth of large whales (except, of course, the sperm whale, which
is a toothed whale), and it is through this gap that the calf suckles.  Or
rather, has milk pumped into its mouth; whether there is active sucking
on the part of the calf we don't know, but given that this would 
help matters, there probably is to some extent.

Undoubtedly calves swallow some seawater in the process, and we really
dont know how they minimize salt water intake.  One hazard of this is that
it is probably during nursing sessions that whales take in larval 
parasites.  There may be rather high mortality in young animals or
yearlings since the young immune system is "naive" or not fully developed
at this time.

I've seen humpback whale calves nursing, both at the surface and underwater
(i.e. that's where I was at the time!)  They seem to alternate sides
quite often.

Phil Clapham