On Mon, 30 Dec 1996 12:50:36, Glenn Morton wrote:
[...]
JB>A fish coming onto the land would need support to keep pressure
>off his soft little belly as it flopped around. Of course, while it
>did so it wouldn't notice its gills collapsing. Nor would it care
>that its body was drying out rapidly, redcuing to zero the area of
>the respiratory surface and effectively stopping the diffusion of
>oxygen into the blood. Easy stuff, this, right? Evolution is so
>simple. All we have to do is imagine all these problems were
>really "selective advantages." Poof!
This might be true of deep-water fish, but I personally have seen
in the Kimberley Region of Western Australia, mud-skippers and a
type of mullet that come up out of the water on to their bellies.
>GM>You forget that there are fish who can do what you say is
>impossible. In recent years Florida was plagued (maybe still is) by
>an African import, the walking catfish. I guess that fish, which is
>able to walk from pond to pond has not heard that you say this is
>impossble. Some one should inform him of this fact. You can't
>cause you are in California. If some one is listening from Florida
>would you please tell those catfish to quit coming onto dry land.
>Jim says it is impossible for them to do this.
The trouble with weak creationist arguments (sorry Jim! :-)) is it
gives evolutionists the idea that when they disprove them, they
thereby prove evolution.
But if by "walk", Glenn means the the sort of walking that a
tetropod uses, then the "walking catfish" does not walk - it slithers
on its belly using its fins as anchor points:
"The walking catfish (Clarias batrachus), recently introduced into
southern Florida, uses its pectoral-fin spines as anchors to prevent
jackknifing as its body musculature produces snakelike movements and
can progress remarkable distances over dry land." (Yerger R.W.,
"Ostariophysi", Encyclopaedia Britannica, Benton: Chicago, 15th
edition, 1984, 13:761)
"Another odd catfish, the so-called walking catfish, Clarias
batrachus, originally occurred in eastern India and Southeast Asia.
In 1968, it was discovered near Boca Raton, Florida, following its
import by tropical-fish dealers. Its maximum length is 56 cm (22
in). In "walking" to areas of deeper water in dry spells, this
catfish moves by a slithering motion combined with a thrashing of its
tail. In addition, a stout spine in each pectoral fin digs into the
ground to help balance and propel the fish. It is able to breathe
air by means of a modified gill arch that forms an air chamber."
(Chambers K.A., "Catfish," Microsoft (R) Encarta. Copyright (c) 1993
Microsoft Corporation. Copyright (c) 1993 Funk & Wagnall's
Corporation)
[...]
On Mon, 30 Dec 1996 21:26:41, Glenn Morton wrote Re The walking
catfish trips Jim:
[...]
GM>I am sorry Jim. I was wrong. I hadn't read the article in
>several years. The fish didn't come from Africa it came from Asia.
Glenn was right the first time. Clarias does come from Africa:
"Clarias has four pairs of barbels near its mouth and is native
around Africa." ("Clarias", Encyclopaedia Britannica, 1984, ii:966)
and Asia:
"Some catfishes (Clarias and Heterobranchus) of Asia and Africa..."
(Yerger R.W., "Ostariophysi", Encyclopaedia Britannica, 1984, 13:761)
GM>Other than that, my facts about this fish are correct. Here is
what >Scientific American said,
>
>"An air-breathing 'walking' catfish that comes from Asia has
>apparently established itself in Florida. Although the state
>normally cherishes visitors, the catfish are unwelcome: they are
>well adapted to the climate and to both fresh and brackish
>waterways, and they are multiplying fast; they are aggressive and
>voracious; they can move overland, searching out new bodies of water
>and thus extending their habitat with exceptional facility and
>speed." "Suffering Catfish!" Scientific American, January 1969, P.
>50
This sounds a bit `journalistic'. No doubt they are able to "move
overland...with exceptional facility and speed" (for fish) due to
Florida's extensive swampland.
>GM>They go on to say
>
>"They looked like catfish but they could obviously survive for long
>periods out of water; they propelled themselves by their fins on
>land, even climbing uphill; there was a story that one had attacked
>a dog.
And this too sounds a bit amateurish for a scientific journal. No
doubt "They looked like catfish" because they *were* catfish! :-)
And as for "there was a story that one had attacked a dog", one can
imagine this vicious catfish, lying in wait to attack the first Great
Dane (or was it a Chihuahua?) which came along! :-)
GM>The fish were soon identified as belonging to the genus Clarias,
>various species of which are natives of South Asia and Africa. [this
>is why I remembered Africa--grm].
So why was it "wrong"? Sounds like a rhetorical trick to add weight
to a shaky argument? :-)
GM>In Clarias the gills are modified; air chambers extend up into
>the skull, each occupied by a 'respiratory tree' that is richly
>vascularized for the exchange of oxygen and carbon dioxide between
>the air and the fish's blood. The auxiliary breathing organ enables
>the fish to stay out of water for 12 hours or more." ibid p. 50
There is no big deal about this:
"Many fishes live in poorly oxygenated water and develop accessory
organs of aerial respiration. In many bony fishes the accessory
respiratory organs often take the form of chambers in the gill region
crowded with capillaries, which while bathed with water retain
quantities of moist air so that physiologically they are lunglike in
their action. A well- known example is Anabas, the so-called
climbing perch, of tropical and subtropical Asia and Africa. A
similar modification is found in the snakeheads (Ophiocephaloidea).
Some catfish, notably Clarias, have extensive gill chambers modified
for air breathing that enable them, to stay out of water for several
hours. A peculiar modification is found in the loach Haplosternum,
in which air is taken into the vascularized intestine, where blood is
oxygenated and returned to the heart unimpeded." (Foxon G.E.H. &
Bannister L.H., "Circulation and Circulatory Systems", Encyclopaedia
Britannica, 1984, 4:626)
"The Clariidae have the same range as the schilbeids (Asia and
Africa). They are naked, often elongated, bottom-living forms with
cylindrical bodies and flat heads. Characteristic of this family is
the possession of an accessory breathing organ in the form of blind
sacs extending along the sides of the vertebral column from the top
of the gill cavity or occurring as spongy tissue in the gill
cavity..." ("Catfishes", Encyclopedia of the Animal World, 1982 reprint,
4:344,346)
"Although gills are typical respiratory structures in fishes, many
freshwater species occupy habitats where the oxygen may be depleted
occasionally or where droughts may force them to live out of water
temporarily. These fishes have evolved a variety of air-breathing
organs, most of which are outgrowths or pouches from the pharynx,
branchial (gill) chamber, or digestive tube. Some catfishes (Clarias
and Heterobranchus) of Asia and Africa have treelike respiratory
structures extending above the gill chambers; others (Heteropneustes)
have elongated, tubular, lunglike sacs extending backward as far as
the tail. The electric eel is a mouth breather, gaseous exchange
taking place through the wrinkled mucous membrane lining the mouth
cavity. Some fishes actually swallow air into the lower part of the
digestive tract, which then also serves as a respiratory structure.
In the armoured catfishes (Doras, Plecostomus, Callichthys) of South
America the thin- walled stomach serves this function. The loaches
swallow air into a reservoir-like bulge from the intestine and void
the remaining gases through the anus." (Yerger R.W., "Ostariophysi",
Encyclopaedia Britannica, 1984, 13:761)
"Another odd catfish, the so-called walking catfish, Clarias
batrachus...It is able to breathe air by means of a modified gill
arch that forms an air chamber." (Chambers K.A., "Catfish,"
Microsoft (R) Encarta. Copyright (c) 1993 Microsoft Corporation.
Copyright (c) 1993 Funk & Wagnall's Corporation)
>GM>This sounds like a future candidate for the transitional form
>between fish and a new form of amphibians.
There is no evidence that Clarias is evolving, and no evolutionist
AFAIK claims it is. Morris in fact claims that the walking catfish
has been ruled out by evolutionists as a candidate transitional form:
"The lung fish, the `walking catfish,' and other fish that seem to
have certain resemblances to land animals, have all been ruled out by
evolutionists for various other reasons." (Morris H.M., "Scientific
Creationism", 1985, p83).
Gould does not hold out much hope for any of this type, calling them
"entirely unsuited for such a transition":
"I might grant the probability of the most crucial environmental
transition- from water to land-if the characteristic anatomy of
fishes implied, even for incidental reasons, an easy transformation
of fins into sturdy limbs needed for support in the gravity of
terrestrial environments. But the fins of most fishes are entirely
unsuited for such a transition. A stout basal bar follows the line
of the body axis, and numerous thin fin rays run parallel to each
other and perpendicular to the bar. These thin, unconnected rays
could not support the weight of the body on land. The few modern
fishes that scurry across mud flats, including Penophthalmus, the
"walking fish," pull their bodies along and do not stride with their
fins." (Gould S.J., "Wonderful Life", 1991, p317)
GM>So now that there are modern examples of fish in transition, who
>use their fins as legs and have auxiliary breathing apparatus, are
>you yet willing to admit that the original transition from fish to
>amphibian might be correct?
I believe the "original transition from fish to amphibian" was
"correct", but I don't see that these `walking catfish' are "modern
examples of fish in transition". In fact, they appear to be in
*stasis*, perfectly adapted to their environment and going nowhere.
They are a good example of the limits of microevolution. They have
developed to the limits of their genetic variability and apparently
cannot develop further unless major mutations are supplied at the
right time, in the right sequence, in the right environmental
circumstances, to increase their store of genetic information, as
even Dawkins tacitly admits:
"...selective breeders experience difficulty after a number of
generations of successful selective breeding. This is because after
some generations of selective breeding the available genetic
variation runs out, and we have to wait for new mutations. " (Dawkins
R., "The Blind Watchmaker", 1991, p247)
These wonderfully adapted fish actually underline the enormous
problems for Darwinist macroevolution. If it was as simple as Glenn
thinks, then why did the "transition from fish to amphibian" *only
happen once", way back in the Devonian? In fact Gould bases a major
plank of his argument from contingency on the sheer improbability of
this fish-amphibian transition happening even once:
"Terrestrial vertebrates could arise because a relatively small group
of fishes, only distantly related to the "standard issue," happened,
for their own immediate reasons, to evolve a radically different type
of limb skeleton, with a strong central axis perpendicular to the
body, and numerous lateral branches radiating from this common focus.
A structure of this design could evolve into a weight-bearing
terrestrial limb, with the central axis converted to the major bones
of our arms and legs, and the lateral branches forming digits. Such
a fin structure did not evolve for its future flexibility in
permitting later mammalian life; (this limb may have provided
advantages, in superior rotation, for bottom-dwelling fishes that
used the substrate as an aid in propulsion). But whatever its
unknown advantages, this necessary prerequisite to terrestrial life
evolved in a restricted group of fishes off the main line-the
lungfish-coelacanth- rhipidistian complex. Wind the tape of life
back to the Devonian, the so- called age of fishes. Would an
observer have singled out these uncommon and uncharacteristic fishes
as precursors to such conspicuous success in such a different
environment? Replay the tape, expunge the rhipidistians by
extinction, and our lands become the unchallenged domain of insects
and flowers." (Gould S.J., "Wonderful Life", 1991, pp317-318)
God bless.
Steve
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