NetMax wrote:
wrote in message
oups.com...

Sorry if I misspelled the name of the strange yet popular catfish. I
had been pondering this fish and think it may be an ancient unchanged
species fish.



Plecos have some arrested features such as air-breathing and a pivot
behind their skull which makes them somewhat prehistoric when compared to
more modern catfish. I think it's just a case of their environment being
fairly consistent (algae, mud & bugs have been around a long time) so
their evolved design has been very successful. When there is a good match
between the design of the creature and the environment, then less of the
normal mutations which occur will be successfully carried forward. At
least this sounds like it makes sense to me.

As a biologist, I don't believe there is any such thing as a "living
fossil." As NetMax has pointed out, a stable envionment may mean that
natural selection changes a species more slowly, however all living
animals evolve. Creatures in a stable environment tend to develop more
subtle, sophisticated mechanisms. Consider, for example, the unrivaled
chemical and electrical sensing abilities of modern sharks. I suspect
there are many subtle changes between modern and prehistoric Loricariid
catfish that cannot be appreciated from merely comparing fossils to the
appearance of the organism.

--
Elaine T __
http://eethomp.com/fish.html '__
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