Is this really a salamander?

[emmyk]

it looks like a gecko to me but I could be wrong and I probably am.

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[usafaux2004]

That looks totally like a Gecko

 

[emmyk]

I know right!

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[Azhael]

100%, absolutely, gecko.

 

[AfroNewtkeeper]

Unbelievably, it lacks the smooth skin and blinking capability of a salamander, as well as the hard outer shell of a coconut crab, so I would assume that it is, in fact, a gecko.

 

[sde]

Tell that dude to look up the difference and definition of a amphibians and reptiles! Seriously, it always bugs me that people call my newts reptiles, or my frogs toads, I guess I am just really specific.

But really, tell him to look those things up. He will find out that there actually is a difference. I'd love to see his argument

 

[AfroNewtkeeper]

I once saw a whole group of people going on about how axolotls were the weirdest FISH that they'd ever seen.

 

[Azhael]

I once saw a whole group of people going on about how axolotls were the weirdest FISH that they'd ever seen.

Little do they know that that is in fact perfectly correct, just not very useful
When i see someone arguing that caudates or whales are fish and somebody else correcting them and saying they are amphibians/mammals i like to step in, tell them they are both correct and see their heads explode.

 

[AfroNewtkeeper]

Wait... what? Are you just using fish in the sense that they're something aquatic?

 

[Azhael]

Nope. Salamanders are tetrapods. Since tetrapoda are a subset of sarcopterygian fish, all tetrapods are fish, therefore salamanders are fish (and so are whales and so are we).

 

[AfroNewtkeeper]

You sly Ichthyostega you.

They still aren't really TRUE fish though.

 

[Azhael]

What´s a true fish, then?
There is no consistent definition that allows you to exclude tetrapods from it. You see, biologically you have two groups of bony fishes, actynopterygii and sarcopterygii. Anyone would recognize most of them as fish. Sarcopterygii, or lobed-finned fishes, comprises coelacanths (obviously fish), lungfishes (obviously fish) and tetrapods (suddenly not fish?). In biology that would be called a paraphyletic group. It makes no sense. If an ancestor is a fish and all your cousins are fish, then you must necessarily be a fish, no matter how different looking or modified you are. The ancestor of sarcopterygian fish was a fish, that´s clear, right? The rest of sarcopterygian fishes, coelacanths and lungfishes are also fish, we all agree. That means that the remaining group, tetrapods can´t possibly be anything other than fish.

Since you mention Ichthyostega, i´m going to assume you like the subject and you have read a bit about it. If its ancestors are lobed-finned fish (animals looking very similar to Tiktaalik, Eustenopteron or Panderichthys, for example) how can Ichthyostega not be a fish? If so, at which point exactly did the lineage stop being fishes and began being tetrapods? When did a lobe-finned fish produce offspring that weren´t lobe-finned fish? When did dogs stop being wolves xD?

The "true fish" concept you are refering to is based on the coloquial use of the word "fish". It is flawed and it makes no sense whatsoever in biology.

Sorry for the long-winded, probably confusing speech, this would have been much easier to explain with a simple cladistic diagram.

 

[CJ1981]

What´s a true fish, then?
There is no consistent definition that allows you to exclude tetrapods from it. You see, biologically you have two groups of bony fishes, actynopterygii and sarcopterygii. Anyone would recognize most of them as fish. Sarcopterygii, or lobed-finned fishes, comprises coelacanths (obviously fish), lungfishes (obviously fish) and tetrapods (suddenly not fish?). In biology that would be called a paraphyletic group. It makes no sense. If an ancestor is a fish and all your cousins are fish, then you must necessarily be a fish, no matter how different looking or modified you are. The ancestor of sarcopterygian fish was a fish, that´s clear, right? The rest of sarcopterygian fishes, coelacanths and lungfishes are also fish, we all agree. That means that the remaining group, tetrapods can´t possibly be anything other than fish.

Since you mention Ichthyostega, i´m going to assume you like the subject and you have read a bit about it. If its ancestors are lobed-finned fish (animals looking very similar to Tiktaalik or Eustenopteron, for example) how can Ichthyostega not be a fish? If so, at which point exactly did the lineage stop being fishes and began being tetrapods? When did a lobe-finned fish produce offspring that weren´t lobe-finned fish? When did dogs stop being wolves xD?

The "true fish" concept you are refering to is based on the coloquial use of the word "fish". It is flawed and it makes no sense whatsoever in biology.

Sorry for the long-winded, probably confusing speech, this would have been much easier to explain with a simple cladistic diagram.

So in essence everything is really a fish but fish don't actually exist? No wonder biology class made my head hurt

 

[Otterwoman]

An inmate fresh to prison is called a "fish."

 

[AfroNewtkeeper]

What´s a true fish, then?
There is no consistent definition that allows you to exclude tetrapods from it. You see, biologically you have two groups of bony fishes, actynopterygii and sarcopterygii. Anyone would recognize most of them as fish. Sarcopterygii, or lobed-finned fishes, comprises coelacanths (obviously fish), lungfishes (obviously fish) and tetrapods (suddenly not fish?). In biology that would be called a paraphyletic group. It makes no sense. If an ancestor is a fish and all your cousins are fish, then you must necessarily be a fish, no matter how different looking or modified you are. The ancestor of sarcopterygian fish was a fish, that´s clear, right? The rest of sarcopterygian fishes, coelacanths and lungfishes are also fish, we all agree. That means that the remaining group, tetrapods can´t possibly be anything other than fish.

Since you mention Ichthyostega, i´m going to assume you like the subject and you have read a bit about it. If its ancestors are lobed-finned fish (animals looking very similar to Tiktaalik, Eustenopteron or Panderichthys, for example) how can Ichthyostega not be a fish? If so, at which point exactly did the lineage stop being fishes and began being tetrapods? When did a lobe-finned fish produce offspring that weren´t lobe-finned fish? When did dogs stop being wolves xD?

The "true fish" concept you are refering to is based on the coloquial use of the word "fish". It is flawed and it makes no sense whatsoever in biology.

Sorry for the long-winded, probably confusing speech, this would have been much easier to explain with a simple cladistic diagram.

You're right in saying that I've read about it, but I can never remember scientific names- just looked up early tetrapods to find an example.
By "true fish" I guess I meant animals that would commonly be called as such. But there's a gap of hundreds of millions of years between humans, whales and newts and fish. Nevermind. xD I hardly know what I'm saying.

Hey, wait. That means the gecko is a fish.

 

[sde]

Wait no, Emmyk, tell the dude its a fish! xD

 

[emmyk]

Hahhaha!

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[Azhael]

So in essence everything is really a fish but fish don't actually exist? No wonder biology class made my head hurt

Not everything, of course. There are many things that aren´t fish but if the term "fish" is going to have any reasonable meaning in biology, then it absolutely must include all tetrapods. You just can´t scape it. Otherwise you would also have to exclude other things that everybody and their mum would swear are definitely, 100% fish.

Afronewtkeeper, that´s the coloquial usage of the term, which as is often the case is incorrect and doesn´t actually reflect reality. I wouldn´t call the coloquial usage the "true" usage...after all we are talking about the same public that can´t distinguish salamanders from geckos and has trouble understanding why birds are dinosaurs. If there is any "true" usage, then surely it must be the biological one.

Since i failed to explain the whole thing, i made a little graphic that i hope is more helpful than my convoluted attempt xDD You might think it´s silly of me to care about putting the point across but it´s an important one, even if it´s just because it´s necessary to understand why all newts are salamanders, for example.

By the way, just look up "paraphyletic group" in wikipedia, that should make things clearer.

 

[slowfoot]

Why stop there? You should just call everything bacteria, or whatever the first living thing was called.

 

[Azhael]

Sure, and it would be perfectly correct, just not useful at all.
There is a conflict in biology which is the fact that on one hand you have a genealogical continuum, uninterrupted. On the other you have the necessity of using language to identify stuff and distinguish it from other stuff. This is by nature a discrete system, with borders, it describes some stuff using a label but excludes the rest. It´s the ONLY way we have to communicate concepts. The problem comes from trying to apply a discrete system to a continuum, obviously there are going to be conflicts. In this case the conflict is that the term "fish" is abstract, it´s not actually real. You can´t choose a point in which the first fish appears because as i mentioned earlier that would mean that at some point a non-fish gave birth to a fish, which is complete non-sense. So we understand the term "fish", or any other for that matter, to be a useful linguistic tool to identify a section of a continuum much the same way that we take the electromagnetic continuum and divide it in the visible light spectrum, the ultraviolet, the infrared, or for that matter the colours of the rainbow (where does red end and orange begin?). Those are abstract, artificial notions, but necessary and very useful.

In the case of "fish", the problem is that the coloquial usage is paraphyletic, it excludes tetrapods for no good reason. In biology a monophyletic system is prefered where the categories are nested. That way, tetrapods are a particular type of fish, the same way that perciformes or lungfishes are particular types of fish. This is the same nested system that makes all newts salamanders but not all salamanders newts. A newt is a specific type of salamander, a bird is a specific type of dinosaur and a tetrapod is a specific type of bony fish.