[Taxacom] Cannibalistic offal (in nature); is such offal awful?

[Stephen Thorpe]

there is direct and indirect cannibalism


indirect cannibalism: species A eats species B, but then gets eaten by (another) 
species B

 

________________________________
From: Kenneth Kinman <kennethkinman at webtv.net>
To: taxacom at mailman.nhm.ku.edu
Sent: Sat, 28 August, 2010 2:43:03 PM
Subject: [Taxacom] Cannibalistic offal (in nature); is such offal awful?

Hi again,
      I  think that I may have thrown my net for comments too widely
(perhaps the mention of lion cubs was not a good idea, even though they
generally are not eaten).  Anyway, my main focus is on adults eating
other adults of the same species (where disease transmission would be
the greatest).  Lots of birds (in particular) are cannibalistic, with
siblings eating siblings, or adults eating the young or eggs of others
of the same species, but disease transmission is probably low in such
cases (in nature). The same is probably true in arthropods (where
females sometimes eat their mates, or even babies eat their mothers).    
        But what I am most interested in is adults eating adults of the
same species.  Hyaenas and monitor lizards, among others, seem to do so,
but they have strongly acidic stomachs that would presumably tend to
protect them from getting infected from such cannibalism.    
      However, today I found a VERY interesting case of hippos in
western Uganda spreading anthrax, which was implicated, at least in
part, due to adult hippos eating other adult hippos.  This is rather
startling since they are mainly vegetarians.  The first wave of such
hippo deaths occurred in 2004, and another wave occurred recently in the
summer of 2010.  This is the kind of situation in nature that may be
most instructive in avoiding disease being spread (by human stupidity)
among adults of their domesticated animals.  
            ----------Ken
--------------------------------------------------
Hi All, 
      Well, it seems the Salmonella contamination in those Iowa chickens
and their eggs has been traced to their feed.  I wouldn't be surprised
if that feed included "chicken offal meal", in which various discarded
body parts of chickens are reprocessed and fed back to other chickens,
thus forcing them into cannibalism.  
      I recall that BSE (mad-cow disease) may well have been the result
of feeding cow offal to other cows (and ultimately then to humans,
especially that deadly outbreak in Britain, and as I recall, perhaps
even some cannibals in New Guinea who relish human brain).  So, is
feeding the offal from the dead of the same species a good idea?  Or is
offal awful (dangerously unnatural) in such cases?  
      Anyway my question is this, are there cases in nature when species
often eat members of their own kind (cannibalism) without a negative 
effect?  Some arachnids do so (spiders, praying mantises, etc.,
sometimes eating their mates), but they don't generally live very long
after doing so anyway, so no big deal), but what about long-lived
species that eat members of their own kind?  Lions kill cubs when they
take over a pride, but I don't think that they eat them.  However, do
scavengers that specialize in eating the dead, such as vultures and 
hyaenas eat dead members of their own kind?      
            ------Ken Kinman 
P.S.  As you might have guessed, I don't think that humans forcing their
domesticated animals into cannibalism is a good idea.  To me the idea of
cannibalistic offal is awful (and dangerous).  Such practice seems bad
for the animals themselves and potentially for anyone who might
ultimately eat them.  The only benefactors of such practices seem to be
the owners of large-scale (industrial) farming of animals.    


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