Is The pleclosumus a living fossil?

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.

On 3 Jul 2005 04:33:44 -0700,
wrote:

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.

I don't think it is, I think it's a usual fish that has evolved
through the ages. Supposedly the Callichthys callichthys armored
catfish is a living fossil, hasn't evolved since the time of dinosaurs
(or whenever).

-Derek

ok thanks

ok thanks

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.
--
www.NetMax.tk

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 '__
rec.aquaria.* FAQ http://faq.thekrib.com

Thanks for a wonderful enlightening response, living fossil may be the
wrong choice of words

Thusly Elaine T Spake Unto All:

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.

Loricariids (armored suckermouthed catfish, to which Plecs belong) is
a young catfish group, the oldest fossil loricariid is, if memory
serves, just 20 million years. As there are no african loricariids,
it's a pretty safe bet they didn't evolve until after africa and south
america split. Meaning that not only is it a modern group, much
younger than e.g. cichlids, but a rapidly evolving and spreading
modern group.

As others have pointed out, "living fossil" is really a meaningless
term. It simply means that a group has been around for a while, was
once speciose, but is now small. Common and speciose groups are never
seen as living fossils, regardless of how old they are - bristleworms
(polychaetes) looking much like present forms, are among the oldest
multicellular fossils ever found, over 600 million years old, but
since bristleworms are still common as muck noone would consider them
living fossils.

On Sun, 3 Jul 2005 02:00:43 -0400, "NetMax"
wrote:

wrote in message
roups.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.

I am an "Intelligent Design" convert. My favorite concept leads
from a "Young God" that gets and "energy kit" and lets it get away
from him and spends 13 billion years gaining some order. By the time
the material world was ready to be molded into "living things" a
"University" had formed. New life forms were created as Doctorate
thesis. Criteria were set out for each project. Successful designs
were allowed to survive until better designs were developed.

I no longer need to wonder "how", but wonder "why?? Following the
same University model, I suspect we are now the projects, only done by
team, each team member is given a human, each team a group. Grouping
used to be easy. Physical barriers such as mountains, rivers or
oceans kept the projects well defined. AS people became more mobil,
languages maintained separations. Today, with our high mobility and
intermixing, cultural walls are used. Its all a vast experiement, no
longer just physical evolution, but social evolution to determine best
social design. We each are important in the scheme, but like lab
animals each is disposable and replaceable.

So, have hope, you may be part of the successful design, a new
survivor equal to the Pleco! g

dick