why did fish have lungs?

[andyandy]

just a quickie.....

In summary, the very first amphibians (presently known only from fragments) were probably almost totally aquatic, had both lungs and internal gills throughout life, and scudded around underwater with flipper-like, many-toed feet that didn't carry much weight. Different lineages of amphibians began to bend either the hind feet or front feet forward so that the feet carried weight. One line (Hynerpeton) bore weight on all four feet, developed strong limb girdles and muscles, and quickly became more terrestrial.

http://www.talkorigins.org/faqs/faq-transitional/part1a.html#tran

why would the first amphibians have lungs and internal gills?

nb. not a wedge against evolution, i'm just curious

 

[Hellbound]

It's my understanding that lungs developed from air bladders used to help control bouyancy. As such, the lungs could still be useful in water for bouyancy, and on land for breathing.

I'd imagine that this simply eveolved before any sort of timing mechanism or dual-purpose structure. The first arachnoids that moved to land (sea scorpions) used very fine gill frills for both air and water, but these were less efficient in air, so lungs provide advantage there.

OF course, IANAB, so this is just my speculation

 

[Rasmus]

why would the first amphibians have lungs and internal gills?

Well, how else should that work?

You're in the water, so you need the ability to breathe there. Before you can crawl to dry land, you had better be able to breathe there, too.

Imagine you went on a diving trip and only started inventing the dive pack once you're six feet under water...

 

[andyandy]

Well, how else should that work?

You're in the water, so you need the ability to breathe there. Before you can crawl to dry land, you had better be able to breathe there, too.

Imagine you went on a diving trip and only started inventing the dive pack once you're six feet under water...

i'm not disputing the fact that an amphibian would need lungs and gills to be able to function on land and in the sea....i was just wondering under what circumstances those lungs would have evolved.....
huntsman's air bladder sounds plausible to me

 

[drkitten]

i'm not disputing the fact that an amphibian would need lungs and gills to be able to function on land and in the sea....i was just wondering under what circumstances those lungs would have evolved.....

Well, there are fish-with-lungs (they're called, imaginatively enough, lungfish) around today. You could always ask (or examine) one....

Air-breathing fish aren't that uncommon. They tend to live (today) in muddy or otherwise oxygen-poor water, so they supplement their oxygen metabolism by gulping it out of the air. Some air-breathing fish) like the mudskipper have also developed the ability to walk on land, so that they can get from one oxygen-poor muddy pool (that's drying up) to another, deeper one.

The evolutionary path from fish to lungfish to mudskipper to salamander makes sense to me.

 

[mummymonkey]

It's my understanding that lungs developed from air bladders used to help control bouyancy. As such, the lungs could still be useful in water for bouyancy, and on land for breathing.

I'd imagine that this simply eveolved before any sort of timing mechanism or dual-purpose structure. The first arachnoids that moved to land (sea scorpions) used very fine gill frills for both air and water, but these were less efficient in air, so lungs provide advantage there.

OF course, IANAB, so this is just my speculation

Air bladders might have developed from lungs.

 

[Soapy Sam]

The evolutionary path from fish to lungfish to mudskipper to salamander makes sense to me.

It's the step from ancestral chimpanzee to Young Earth Creationist I have difficulty with. What evolutionary advantage can anyone see here?

 

[GodMark2]

It's the step from ancestral chimpanzee to Young Earth Creationist I have difficulty with. What evolutionary advantage can anyone see here?

Easy identification of viable mates.

How many times have you seen this:

Average Joe walks into a bar and sees average Jane. Joe says "Hey, it's that time, lets get married" Jane Says "Sure. By the way, what's your name?"

Replace "Bar" with "Fundamantalist Young Earth Creationist Church" and the story suddenly becomes much more believable.

 

[Meffy]

Why did fish have lungs?

So they could sing, of course.

 

[Oldpossum]

IIRC In recent times (like the last 40 million years or so) at least five families of Ray finned fishes evolved the ability to breathe air.

They are respecivly, the Lungfishes, Carps, African Chilids, Goriamis & Siamese fighting fish, and Walking Catfish.

Mudskippers BTW, don't breathe air, they hold their "breath" when on land, and supliment the dissolved oxygen in the mouthfull of water, with absorbing some oxygen through their skin.

As an aside, I've often wonders if we could gene splice the relevent bits from the African Climbing Perch, the Hatchett Fish, and the (Fish that lays its eggs out of the water, forgotten the name of it now) to come up with an new species of fish that is compleatly Aerial/terestrial in it's habits.

It would spent it's time flying around the forest hunting insects, perching in trees, and of course, laying it's eggs in a nest up a tree!

 

[drkitten]

Air bladders might have developed from lungs.

Not according to the fossil record....

 

[Scott Haley]

Flish

As an aside, I've often wonders if we could gene splice the relevent bits from the African Climbing Perch, the Hatchett Fish, and the (Fish that lays its eggs out of the water, forgotten the name of it now) to come up with an new species of fish that is compleatly Aerial/terestrial in it's habits.

It would spent it's time flying around the forest hunting insects, perching in trees, and of course, laying it's eggs in a nest up a tree!

Just like the "flish" from the TV show "The Future is Wild." It
was show about possible future evolution.

 

[Scott Haley]

African Lungfish

I read that the African Lungfish uses his air breathing ability to survive his pond drying up. When the water goes away, he stays in a ball of dried mud on the dry lake bottom. He hibernates there, breathing air, until the rain comes again.