Difference Between Amphibians and Fish

[Namio]

I'm thinking about eels, lungfish, mudskippers vs. amphiumas, sirens, axolotls, etc. What are the differences?

In addition to what Macle said, amphibians do not have scales like most fish do. No amphibians can tolerate salt water due to their semi-permeable skin (salt will dehydrate amphibians pretty quickly), whereas fish do not have a permeable skin. I'll also state the obvious that no fish have limbs with digits like most amphibians do.

From an evolution stand point, fish (specifically bony fish) gave rise to amphibians. Not the other way around.

Amphibians have lungs.

You are right about that with most amphibians, but a group of diverse salamanders (Plethodontids) actually do not possess lungs. On the other hand, not all fish are lungless. A group of fish (lungfish) actually do have lungs.

Seriously...... is that a real question?

Cam, that is as real as a question can get. It's got a question mark, right?

Go make friends with google or something.

Great suggestion. Maybe that's exactly what n321 did, and frogforum showed up!

[n321]

Namio, thanks for taking my question seriously.

What prompted my question was, in my Principles of Biological Diversity class, we learned bout the evolution from fish to amphibians. I do think this is a legitimate question, as I know there are more than a few amphibians that lack lungs, and some fish (lungfish that have lungs. Also, do ALL fish have scales? It seems like some eels lack scales...

If you aren't interested in this topic people, don't participate. It's as simple as that.

[n321]

Another thing, caecilians lack limbs completely, so...

[Pluke]

Catfish don't have scales, neither do sharks.. I can't really think of any others off hand, but I'm sure there are more of them.

[Namio]

Here's my own quote:

In addition to what Macle said, amphibians do not have scales like most fish do.[...] I'll also state the obvious that no fish have limbs with digits like most amphibians do.

Another thing, caecilians lack limbs completely, so...

Haha, good call! I agree, that's why I put a "most" in front of amphibians.

Also, do ALL fish have scales? It seems like some eels lack scales...

Another good call, so I did the same thing with fish.

[n321]

I was thinking that there aren't any amphibians with fins (although not all fish have true fins either...).

[Namio]

I was thinking that there aren't any amphibians with fins (although not all fish have true fins either...).

That is true, but aquatic salamanders have dorsally flattened tails that work just like a fin for swimming

[n321]

From Merriam-Webster dictionary:

Fish--any of numerous cold-blooded strictly aquatic craniate vertebrates that include the bony fishes and usually the cartilaginous and jawless fishes and that have typically an elongated somewhat spindle-shaped body terminating in a broad caudal fin, limbs in the form of fins when present at all, and a 2-chambered heart by which blood is sent through thoracic gills to be oxygenated

Amphibian--an amphibious organism; especially: any of a class (Amphibia) of cold-blooded vertebrates (as frogs, toads, or salamanders) intermediate in many characters between fishes and reptiles and having gilled aquatic larvae and air-breathing adults

This goes into the heart differences in more depth:
The Vertebrate Animal Heart: Unevolvable, whether Primitive or Complex

Sorry, just realized that website is just a bit biased/propaganda-ish
I don't mean to go into an evolution/intelligent design discussion, I just thought the differences in heart structure was interesting...

[arielgasca420]

this was an interesting post. I am glad I read it entirely. Most of the animals you mentioned, like lungfish, I did not know existed. (i am more of a plant fanatic)

[mpmistr]

In addition to what Macle said, amphibians do not have scales like most fish do. No amphibians can tolerate salt water due to their semi-permeable skin (salt will dehydrate amphibians pretty quickly), whereas fish do not have a permeable skin. I'll also state the obvious that no fish have limbs with digits like most amphibians do.

Actually, the African Clawed Frog can survive in brackish environments and water with up to 40% salinity. Truly the cockroach of all amphibians.

[Namio]

I have no doubt that ACF have some salinity tolerance of saltwater, but my question is that how can they tolerate up 40% of salinity when our ocean is about 3.5% in salinity...?

So perhaps you're saying that ACF can live in brackish water that is up to 40% of the 3.5% saltwater? Even then I suspect they can't withstand that salinity for majority of their lifetime. It's probably more of a temporary tolerance.

[mpmistr]

I have no doubt that ACF have some salinity tolerance of saltwater, but my question is that how can they tolerate up 40% of salinity when our ocean is about 3.5% in salinity...?

So perhaps you're saying that ACF can live in brackish water that is up to 40% of the 3.5% saltwater? Even then I suspect they can't withstand that salinity for majority of their lifetime. It's probably more of a temporary tolerance.

Yes, 40% of the 3.5% saltwater; brackish conditions. I know they've invaded brackish conditions in the wild, not sure if they can survive in it permanently though, They are quite salt tolerant -- for a frog.

[UncleChester]

Yes, 40% of the 3.5% saltwater; brackish conditions. I know they've invaded brackish conditions in the wild, not sure if they can survive in it permanently though, They are quite salt tolerant -- for a frog.

I think the Crab-eating frog, Rana cancrivora, is the winner for salt water tolerance. It can supposedly handle 80% of sea-waters salinity for days if it is acclimatized to it. Its tadpoles can manage water saltier than the sea. Here's the study (full pdf is even available): Osmotic Regulation in the Crab-Eating Frog (Rana Cancrivora)

[mpmistr]

Yup that is pretty impressive indeed. I'd say that would be the winner.