(I'm just going to address direct replies to myself at this point, as I'm busy at work; however, i would not you've cited a pair of biased creationist sources - no peer review! - which we've seen to prefer dogma over science in previous examples, and that the mudskipper is a great example of the adaptive advantage and thus selection reward/pressure of developing an ability to breathe outside the water. The lungfish, of course, does have primitive lungs which are of great advantage in de-oxygenated water.)
We're talking about them BOTH being on the surface of the water; smaller fish gulps air to increase its oxygen, but suddenly can't dive away from the predator like it normally could. Fish gets eaten. (But that's really just going to get into a tangent on fish's evasive manuvers, so let's not go there. Big grin ) (You probably think that's the most intelligent thing I've said so far.)
You've completely missed the point, actually. But it's ok, because it gives me a good opportunity to explain selection in action.
Every predator-prey interaction is a risk-reward situation. Both expend energy in a chase situation; the predator expends less in these situations, because it's 'running' for its dinner, not its life (as the prey is).
Ok. So, any advantage the prey gets is manifold, because it can afford to spend more on running away (a predator has to use energy in a way allowing multiple hunts, after all). Now, let's go back to the swim bladder.
The predator is not in the surface of the water. It doesn't have the natural bouyancy because - shock - it has no swim bladder. Bear in mind we're talking about evolutionary advantage here; a predator might develop a bouyancy mutation (to simplify; not necessarily a swim bladder at this point, just an ability to regulate bouyancy) before prey, but it won't be useful enough to be selected until the prey is living on the surface, i.e. bouyant. I believe this is sometimes referred to as the 'red queen' effect, i.e. is akin an evolutionary arms race.
So, initially, this bouyancy mutation is selected for the prey, because the predator, lacking bouyancy, resides
at the bottom. Remember, swimming - going - up takes more energy than going down; same as it's more useful for a bird to fly up away from a ground based predator, than for said predator to jump up in the air and the bird dive away.
Moreso, the predator will not be inclined to 'hunt up', as most fish - most prey - at this point will lack a bouyancy aid, and thus be in the lower reaches of the water; within the more optimum hunting (energy) range. However, should a predator evolve a bouyancy aid of its own, then that can be selected, because it opens up a new hunting
niche for that species - it makes it energy-efficient to hunt.
Oh, what the hell; i'll do a wee bit more;
On the topic; "Did Lungfish Evolve Into Amphibians?"
Firstly, the biblical quote at the top should show you the hidden (or not) agenda here, and the inherent bias. Moreso, should the lack of any scientific reference source. It's worth also noting John Morris, Ph.D., is a
geologist (which also makes me wonder - has he ever published anything? And also note that he was caught out in a hoax;
http://www.talkorigins.org/faqs/ark-hoax/jammal.html), not a biologist, and thus completely unqualified.
Secondly, there appears to be a deliberate attempt to mischaracterise lungfish evolution; for example, no mention that mammals are believed to have evolved from the
Devonian lungfish (Osteolepiformes). He's also - deliberately, I'd wager - making the completely erroneous statement that evolution would require synchronized changes rather than sequential; presumably to create the 'false chance' type arguement we've seen to many times before.
Here's a bit more -
with references - on transitional forms from fish;
http://www.talkorigins.org/indexcc/CC/CC212.htmlThis goes on a bit further;
http://www.talkorigins.org/faqs/faq-transitional/part1a.html Again, it provides references.
Also, a bit on his mischaracterisation of the status of the Coalacanth;
http://www.talkorigins.org/indexcc/CB/CB930_1.htmland finally, to mention the Rhipidistia;
http://en.wikipedia.org/wiki/RhipidistiaInteresting how he tries to wrongly imply said families position in evolutionary history, somehow - shock - omitting that it's seen as a 'root' of the fish evolutionary tree and describing it more as if it were some sort of leaf branch. Look at
http://www.palaeos.com/Vertebrates/Units/140Sarcopterygii/140.400.html and see how 'far' away the Tetrapod branch is, for example.
I hope you also note how he takes 3 very specific examples; I'd guess because those were the 3 easiest to 'disprove', even though things like, er, basic facts or any form of scientific references went missing along the line.....not to mention twisting the context of them. Tut-tut, not very scientific. Propagandistic, one might say.