Shark pre adapted to crawling around on land...

[Moontanman]

Could this shark be a window into how fish adapted to the land before they were able to live out of the water?

 

http://en.wikipedia.org/wiki/Epaulette_shark

 

This mode of locomotion even enables the shark to crawl out of the water to access isolated tidal pools.[8] The gait of the epaulette shark is convergently similar to those of tetrapods such as salamanders, suggesting that the movements needed for walking on land may predate, and facilitated the evolution of, the first terrestrial vertebrates.[9]

 

[Phi for All]

Is there much of a current on the ocean floor? Trying to remain stable fighting a current builds muscles. Could the ability to move along the floor finding tasty tidbits without being carried away eventually lead to crawling up out of the water?

[Moontanman]

Is there much of a current on the ocean floor? Trying to remain stable fighting a current builds muscles. Could the ability to move along the floor finding tasty tidbits without being carried away eventually lead to crawling up out of the water?

 

 

There can be currents but there lots of if involved, this shark actually crawls onto land to get from one tide pool to another. I'm not sure if this sharks legs would help in currents, water tends to push pretty hard, most of the fish adapted to high currents are either torpedo shaped to swim into it or flat to cling to the bottom. I am not aware of a fish that would use this method to counter currents..

I've seen many fishes that hang around behind cover to avoid the current as well. things like pilings are often points of harbor in a strong current...

[Ringer]

There are only so many ranges of motion when your axial muscles only allow for lateral undulation. So it's not surprising that that lateral movement would be the primitive motion before specialized muscle groups developed. But terrestrial ancestors where sarchopterygians (lobe finned fishes) not chondrichthyes, so there were probably differences in the specifics of their movements.

 

Is there much of a current on the ocean floor? Trying to remain stable fighting a current builds muscles. Could the ability to move along the floor finding tasty tidbits without being carried away eventually lead to crawling up out of the water?

 

IIRC early amphibians evolved in swamps or some other freshwater habitat without a strong current.

[Moontanman]

There are only so many ranges of motion when your axial muscles only allow for lateral undulation. So it's not surprising that that lateral movement would be the primitive motion before specialized muscle groups developed. But terrestrial ancestors where sarchopterygians (lobe finned fishes) not chondrichthyes, so there were probably differences in the specifics of their movements.

I wasn't suggesting chondrichthyes were ancestral to terrestrial animals...

 

IIRC early amphibians evolved in swamps or some other freshwater habitat without a strong current.

I'm not really sure this can be supported by anything but speculations can you provide some citation for this?

[Ringer]

I wasn't suggesting chondrichthyes were ancestral to terrestrial animals...

I was more talking about to the quote about convergent locomotion.

 

I'm not really sure this can be supported by anything but speculations can you provide some citation for this?

Well, I can't find my Gaining Ground by Jennifer Clack (where I thought I read that) or my anatomy of chordates book that I also thought had that in it. The 9th edition of Vertebrate Life says that the earliest tetrapods evolved in shallow marine or estuarine environments, in other words it appears I was mistaken.