The Coelacanth

[EGGO]

I was reading about the Coelacanth recently and how the fish predates even the dinosaurs (dinos 65 million years ago, the fish 400 million), and being a person who mildly understands evolution, I want to ask a few questions regarding this fish.

Mostly, I would like to know why the fish has not changed so much in physical appearance (I believe it's macroevolution?) after so many millions of years.

Or, has the Coelacanth ever even evolved?

How much credibility does this give anti-evolutionists since it looks like it hasn't evolved and was found alive?

Thank you for your time.

I read the articles here. http://www.dinofish.com/

[variant 13]

I would like to know why the fish has not changed so much in physical appearance (I believe it's macroevolution?) after so many millions of years.

It hasn't needed to, things (plant/animals) only change when there is pressure (environmental) to do so.

Or, has the Coelacanth ever even evolved?

Well if you accept evolution then yes.

And from the first quote:

You have pointed out an important point "physical appearance" - evolution involves every part of a things biology, its cellular structure, enzymes, development, etc.

How much credibility does this give anti-evolutionists since it looks like it hasn't evolved and was found alive?

little or none.

[anthrosciguy]

The Talk Origins archive is always a good place to look when you have a question like this. They've cobvered many, if not most, of these type questions and this one is no exception.

From their Feedback column (http://www.talkorigins.org/origins/feedback/oct03.html)

And a link with more information (http://www.talkorigins.org/indexcc/CB/CB930_1.html)
and one of their "posts of the month" on the subject (http://www.talkorigins.org/origins/postmonth/sep02.html)

[God Fearing Atheist]

Originally posted by EGGO
I was reading about the Coelacanth recently and how the fish predates even the dinosaurs (dinos 65 million years ago, the fish 400 million)...

Just to be clear, non-avian dinosaurs went extinct 65 million years ago, but first appeared much earlier (somewhere in the Triassic; the oldest known dino remains are about 230 million years old).

-GFA

[Duvenoy]

'Ol' four Legs' has indeed evolved. It has adapted to modern conditions.

Today, if is a deep water fish and although it looks pretty much as it did in yesteryear, it had to change to thrive in modern conditions. It is very good at what it does: hanging out in caves at depths of 600 feet+. Call it microevolution if you must.

The modern coelacanth is not the lobe-fin that gradually became an amphibian. This was another species altogether.

This was not the only lobe-fined fish ever to exist. There were many species. Our modern example is simply one that survived and prospered pretty much as is/was. And it is only one among many species that has survived the eons virtually unchanged in appearance. The horseshoe crab and the chambered nautalus are even better examples.

The bottom line is: so what? Why can a creature that can fill an enviornmental niche adequatly not pretty much keep it's form?

doov

Edited to remove repititious link.

[MrDarwin]

Evolutionary theory says that living things have evolved, but there is nothing that says that a particular group must evolve, or will evolve (or how quickly or how much it will change over time). In fact, the fossil record demonstrates that different groups have evolved at vastly different rates (at least with respect to morphology, which is all we can measure from the fossil record).

But coelacanths have indeed evolved, or changed over time. "Coelacanth" is commonly used to refer to a single living species, but in fact "coelacanth" refers to a group with a long fossil record. Many people make the mistake of confusing the species with the group, and when fossil coelacanths are mentioned, they picture something identical to what's alive today. But over the course of the fossil record of this group, coelacanths changed quite a bit; and although there is a long gap in the fossil record of this group, the species alive today is not the same as the last known species in the fossil record (they are classified in different genera). The modern species of coelacanth is, in fact, unknown from the fossil record. So when somebody (including scientists, who really ought to be more careful) says "the coelacanth has not changed in millions of years", what they really mean is "as far as we can tell, it is very similar to the ones that were alive millions of years ago."

There was a very interesting study published a couple of years ago in which somebody measured the evolution of another group of "living fossils", horseshoe crabs. This is an ancient group that has also changed little in millions of years, but in this case there are two or three different genera still alive, and the fossil record shows approximately when these genera diverged. Molecular studies comparing the genetic (as opposed to purely morphological) differences between these genera showed that they had changed approximately as much as different genera of crustaceans that had diverged at about the same time, but which had changed much more radically in morphology.

[Gregg]

Originally posted by EGGO
being a person who mildly understands evolution[/url] Not trying to be sarcastic, but you don't mildly understand evolution, if you think it means a creature MUST change into something else over hundreds of thousands or millions of years (not that the coelacanth hasn't evolved, it just hasn't changed that much in appearance). If a species fits perfectly into its niche and nothing happens to drastically upset the environmental equilibrium, then there's no selective pressure on the species--thus evolutionary change, if any, is very slow and subtle.

Besides, even if the coelacanth DID evolve into something else, that doesn't mean there couldn't still be coelacanths. One population of coelacanths could evolve into another species due to unique environmental pressures in its particular territory, while the other populations remained basically unchanged.

If you don't understand this basic stuff, you can't say that you even "mildly" understand evolution. You have a lot more studying to do.

[Urvogel Reverie]

Originally posted by EGGO
I was reading about the Coelacanth recently and how the fish predates even the dinosaurs (dinos 65 million years ago, the fish 400 million), and being a person who mildly understands evolution, I want to ask a few questions regarding this fish.

Mostly, I would like to know why the fish has not changed so much in physical appearance (I believe it's macroevolution?) after so many millions of years.

Or, has the Coelacanth ever even evolved?

How much credibility does this give anti-evolutionists since it looks like it hasn't evolved and was found alive?

Thank you for your time.

I read the articles here. http://www.dinofish.com/


the extant coelacanth, Latimeria is not the same sepcies as those seen in the Devonian, when ACtinistia was at its zenith, so the question is really pointless, and I find it thoroughly amusing when creationists use it.

Urvogel Reverie

[pz]

A few examples of old coelacanths:

http://pharyngula.org/images/coelacanths.jpg
A. Macropomoides orientalis, from the late Cretaceous.
B. Rhabdoderma elegans, late Carboniferous.
C. Allenypterus montanus, early Carboniferous.

I think the differences are pretty obvious.

(The figure is from Jennifer Clack's Gaining Ground.)

[elektra]

Oh reminds me of Viv Stanshall banging on about the Ceolacanth who Ceolacouldth and wouldth. Almost broke my rhinocratic oaf!