Always wondered this...Biology question

[samurai_sushi]

*EDIT*
How come Insects, Arachnids, Myriapods, and Amphibians aren't established or found in saltwater? Why are Crustaceans established in saltwater but the other three are not? How come the more aquactic Amphibians cannot live in marine environments but Reptiles with more terestrial cousins survive long term?

 

[mie]

Who says everything else evolved.
Come on a fish that just decided to talk a walk outside of the lake.

 

[aquaknight]

Yet? We could have come along to early in the timescale? Lack of enough reason (food)? There's enough 'things' that looks like insects in the sea already. For amphibians, probably has to do with the way saltwater creatures drink the water. Freshwater fish literally drink the water. Saltwater fish 'absorb' saltwater through their bodies.
Just some ideas off the top of my head...

 

[ric maniac]

Originally Posted by mie
Who says everything else evolved.
Come on a fish that just decided to talk a walk outside of the lake.

well said.

 

[ophiura]

OK - if you don't have an answer other than "there is no evolution" I would ask you not to get into the thread and start a debate. We don't need to go down that road, yet again.

 

[kjr_trig]

crustaceans and insects are considered very closely related BTW, essentially you could say crustaceans are the insects of the ocean.

 

[kclester]

i dont know why no amphibians did when some of the reptiles did kinda strange huh

 

[jerthunter]

I'd say that it has to do with niches, they already have a niche they fill and have no experienced a pressure to move to highly saline environments.
Another option is naming, we name groups, atleast historically, based on shared adaptive strategy and appearance, and living in freshwater and land is one adaptive strategy.

 

[mie]

Originally Posted by ophiura
OK - if you don't have an answer other than "there is no evolution" I would ask you not to get into the thread and start a debate. We don't need to go down that road, yet again.
All creatures are to perfect to have evolved it does'nt make sense.
And i believe we are all entitled to our own opinions and beliefs.
Lets just keep it civil and understand that everyone is entitled to there opinons and beliefs
No harm no foul.

 

[jerthunter]

Originally Posted by mie
All creatures are to perfect to have evolved it does'nt make sense.
And i believe we are all entitled to our own opinions and beliefs.
Lets just keep it civil and understand that everyone is entitled to there opinons and beliefs
No harm no foul.

Would you prefer the word 'change' to 'evolve'. Regardless of how things started most people would agree that things change or adapt to new environments. Like freshwater fish making it out into brackish water or saltwater animals moving into freshwater lakes.
evolve is not a dirty word.

 

[1journeyman]

As Jerth said, classification is a big part.
Insects and many of the sea creatures belong to"
Kingdom Animalia
Phylum Arthropoda
It's at the class level that they diverge.
As for amphibians. My guess would be it's the way they absorb water in their skin that keeps them out of saltwater. They would quickly dehydrate and die in saltwater...

 

[kclester]

i agree journeyman.....is there any other marine reptiles other than sea snake and marine iguana's ?

 

[kjr_trig]

Originally Posted by kclester
i agree journeyman.....is there any other marine reptiles other than sea snake and marine iguana's ?
Turtles (many varieties), there are salt water Crocodiles too, I think even some Alligators live in saltwater

 

[kclester]

well those are obvious reptiles that live in the ocean that most people already know about lol....i guess i shouls have listed those also but i figured everyone would have already knew of those neways...sorry....but i didnt know gators wondered into salt water

 

[kclester]

samurai siad there arent any insects evolved to live in salt water but if im right isnt there spiders that live in salt water. I may be wrong but im sure someone knows something about them

 

[reefkprz]

Originally Posted by AquaKnight
Freshwater fish literally drink the water. Saltwater fish 'absorb' saltwater through their bodies.
Just some ideas off the top of my head...
you have that backwards, saltwater drink mainly through swallowing, freswater drink mainly by absorbtion. but both use osmoregulation.
Freshwater fish absorb most of the water they need through their skin via osmosis (is the net movement of water through a selective permeable membrane from a region of low solute potential to a region of high solute potential due to their hyperosmotic environment), not through their gills. The gills are for respiration.
Most saltwater fish (Hagfish, Sharks, Rays differ in osmoregulation) actually drink the water the live in, as the salt in the water is constantly pulling H2O from their bodies in a reverse respiration (hypoosmotic environment), this is why some fish such as catfish are sensitive to salt in the water, but this is also why some fresh water fish are helped by salt to generate a mucous slime coat on their skin which is necessary for disease prevention. Proper electrolytes, magnesium and other elements are important for slime coat generation.

 

[jerthunter]

Originally Posted by kclester
samurai siad there arent any insects evolved to live in salt water but if im right isnt there spiders that live in salt water. I may be wrong but im sure someone knows something about them
They aren't classified as insects, if I'm thinking of the same thing you are. They are classifed a pycnogonids.

 

[kclester]

oo ok i never knew that...but do you think that they may have evolved from some type of land spider ?

 

[jerthunter]

Originally Posted by kclester
oo ok i never knew that...but do you think that they may have evolved from some type of land spider ?
I don't know. lets see, spiders, horseshoe crabs, seaspiders and sea scorpions all are in the subphylum chelicerata

 

[mie]

Never said evolve was a bad word.
Some people take it pretty seriously.
I would have to agree that change is a better word, and is an easier way to get people to understand our world and what it started from and how it changes, Whithout starting alot of controversy.
For instance, how does a salmon know to return to the exact same stream it was born in? It was hundreds of miles away in the vast ocean. How does it know what way is north and when to turn to the east to the river. (the same river). Is this change (evolution) over thousands of years? Or was it created so perfect that it has always done this?