Scale Sizes of Fish

[theartist]

Been thinking about this a lot and can't get my head round it.

Everything on a fishes body seems to relate to how it feeds or surviving in the water it lives in, from upturned/downturned mouths on surface/bottom feeders respectively all the way through to barbules for the rummagers to big eyes for the sight predators, from body shape, fin size, spikes on gill covers, the list goes on... seem to have a purpose befitting the fish, in regards it's quarry, avoiding being something else's quarry or the surrounding environment.

Then you get to the scale sizes. I'm thinking a tench has tiny scales as it's often in and out of silt and dense weedbeds which makes sense - But If so then why do trout and salmon have similar sized scales?

Then if trout, salmon and barbel have small scales because they live in fast water - Then why do Mahseer have massive scales?

Evolution seems to have bypassed scale sizes or is it still a work in progress?

Your thoughts...

 

[bullet]

It is an intersting one, Marseer might need the big scales because they favour very fast water and need protection, but then Chub don't and they have quite big scales.
Salmon are Anadromous and Trout can be, so maybe that has something to do with small scales?
Eels are Catadromous and have no scales at all..!
It's certainly a weird one!

 

[Philip]

Perhaps because you have made the giant jump to assuming scale size is determined by enviroment.

It may not be.

...But dont ask me what its determined by.

 

[Kirky_1]

Fish Scales 101: Placoid, Ganoid & Other Types | Earth Life

Fish Scales 101: Placoid, Ganoid & Other Types Of Scale Explained. Fish scales are the small, almost plastic, flakes that cover their body.

www.earthlife.net

Too much to cut n paste

Might give some answers

 

[theartist]

The size of scale relating to how the fish move is an explanation I had overlooked, certainly eels, catfish and to a lesser extent tench can twist on a sixpence and need to in their environment. Pike with their small scales throw a curveball on that one in their straight line approach, for sure they need to twist during the hunt for prey but most times they seem pretty direct, pretty sure there are predators out there that have large scales which contradict that theory though, nile perch or tarpon spring to mind

I also thought the salmanoids migration may have something to do with their scale size, perhaps also their breeding habits and the possiblitly of picking up infections or scars on the gravel. Do all gravel breeders have small or scaleless underbellies? Thinking of it I think all fish do anyway though.

I do love the way when you look at all the different fish shapes, parts of their anatomy and how they work they do have some serious diversity.

 

[108831]

Hi Rob,I think sea trout and salmon spend long periods at sea,where there are some pretty nasty parasites and their scales may give protection to their fairly soft,delicate flesh beneath,but it could just be a fluke of evolution,some of these are successful,some fail so badly extinction could be possible,we only have to look at our situation with coronavirus now,with it mutating and finding new ways of getting at the silly humans...

 

[theartist]

I did think about sea lice Alan but then thought about other migratory fish like Mullet which have larger scales

 

[108831]

Yeah,their flesh is a bit tougher though...who knows really...

 

[Philip]

I suspect a fishes ancestory plays a part. Large reptile looking type of scales on some of the ancient species for example.

In addition depending on the species some fish scales grow in size as the fish grows while on other species they just add new scales (many Sharks for example)..that will probably have a bearing, as will the nature of the fish itself …is it a fast swimmer or a slow bottom dweller. I recall reading or seeing something about how some surface swimming shoal fish have large bright scales as they are more likely to reflect light to disorientate a predator attacking them.

In short its probably because it’s a complex combination of 1001 different things which is why its difficult to pick out just 1.

 

[no-one in particular]

Prehistoric fish do not seem to possess much in the way of scales, what that means I don't know but something to consider. The only other thing I can add is bird feathers are evolved from dinosaur scales. The only thing I can think of is that fish scales in some species may have not evolved much when fish branched off from a more common ancestor. Its a pretty random thing; evolution relies on the chance mutations and then having the opportunity to take hold, maybe it happened for some species more while others it didn't so much irrespective of their environment, but I am just guessing, but it could be just some fish are still more like their ancestors than others. Just chucking some thoughts around really but, interesting topic.

 

[108831]

I would imagine many species are on different parts of the evolutionary scale and as they all have their own starting point,the changes are staggeringly different...