Fish vs Aquatic Mammals

C

curioucity

Unbelievable and odd
Registered Senior Member
Hi

There's something that I pretty much have been forgetting to ask for quite a long time. It's about why fish swim in a different way than aquatic mammals like dolphins. We are mostly aware that fish swim by 'wiggling' (chances are I pick a weird word, sorry bout that ^^;; ) sideways (left-right). Compare that to dolphins and other aquatic mammals that 'wiggle' vertically when swimming. For creatures with relatively similar body shape (the fish-like form), why do they have different movement style?

As an additional point, from what I've read and watched everywhere (including the internet), aquatic reptiles also tend to swim in similar fashion. Now, when related to many legged reptiles' locomotion style (I'm not very sure if turtles' movement is any similar to lizards'; they don't seem that wiggly), I assume that reptiles and fish do have common ancestry. But that's just an additional point not to take the spotlight from my original question.

I read that dolphins & co. originated from land mammals. With that case in point, I have made some guesses to my own question on the first paragraph.

I notice that when mammals bend their body, or specifically their backbone, they tend to bend them up and down, best demonstrated by running predators such as the big cats. This, for whatever reason, seems to be an okay locomotion method, so when the dolphin ancestors begin to swim in the seas, they somehow keep this vertical movements rather than going back to fish-like horizontal wigglings.

Well, I just feel like wanting to ask why fish and dolphins swim different styles, and additionally try to answer myself. I'd like to hear what you have to say as well though, just to be more sure.

Thanks ^_^
 
well they got different body mass...so they have to propel themselves through water with different inertia. And dolphins are mammals...
 
It has to be bone structure. Dolphins move their tails up and down, while sharks of the same size or larger go side to side. Same with whales vs whale sharks.

Do they have a tailbone? Hips?
 
Hmm..... I just googled a bit, and found that hipbones don't seem to be present in dolphins and whales, at least not blatantly visible (in that they may have shrunk so much). Tailbone is perhaps not too distinguished, considering that in mammals tailbones are strictly extensions of the backbone.....

I'm currently looking for a good image for seal/walrus skeletons for more comparisons... afterall, I kinda misdubbed the title as aquatic mammals rather than Cetacea. But still I guess I may kick em out of discussion for now, since they're not strictly fish-like in shape xD Plus, I probably hasn't explicitly omit rays from my fish discussion on my first post, so let it be now ^_^
 
Not all fish do the wiggle,
flatfishes ( flounders, sole, halibut etc) do the vertical propulsion. They have done some serious body realignment over the years to facilitate this.
Crocodiles and monitor lizards, iguanas all do the horizontal version.

Stingrays too, do the vertical wiggle ( I dived today, saw two types of ray and a flat shark, he did the horizontal btw.)
 
Sorry Gustav, didn't mean to lose you with the vernacular.
I was trying to say that different species of fish, mammals and reptiles display the different modes of aquatic propulsion, vertical and horizontal.

A mammal which uses horizontal; the otter ( but it also uses its webbed feet and I'm sure throws in some vertical propulsion)
Seals are particularly pliant too and exhibit multiple propulsion techniques.
 
lol @ ya, guyz :p


To Gustav:

Thanks for the links to old articles. Haven't read the one on 2006 (5 pages :p), but would like to read em once spare.


and Spud

Thanks. Yes, like you said I did forget to put some exceptions (like rays, and then you also just mentioned otter; I've never read otter articles in detail), but please never mind that.

So now with those exceptions you mention, I sure would like to assume that the flatness orientation of the body kinda determines whether the animal uses horizontal or vertical locomotion. But then again, crocodiles tend to be horizontally flat, so my idea just now seems like rebutted..... but then I just remembered that swimming reptiles tend to have vertical tails, in accordance to the vertical standing of a lot of fish......

Now I kinda wonder why, or whether, the tail shape is really that important in determining the wiggling direction?

Hmm....
 
Spud Emperor said:
....
flatfishes ( flounders, sole, halibut etc) ... have done some serious body realignment over the years to facilitate this....
Click to expand...
Yes, they certainly do! When young, they look much like any other minnow, with one eye on each side, but later as they become "bottom dwellers" the "belly side" eye migrates onto the top side! (I think the gill slits move also, but am not sure of that.)

Human eyes, at least part of them (the retina) also migrate, but it is all done before a normal birth. I.e. the retina is part of the brain in embronic stage and migrates to the front of the face to become the most functional part of the eye.

I have alway thought that there might be chance to develope a "non-invasive" test for alhiemers by looking at the retina's optical reflection spectra very carefully, but probably not as it tends to attack some neural tissue more thna others. As far as I know, there still in no definite test for that disease, except post mortum examination of brain tissue.
 
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It's dependant on the body type, it's not that dolphins WON'T wiggle side-to-side but they CAN'T. Same as fish, they can't wiggle up and down, and they can't swim like we do, so they wiggle side to side.
 
Read-Only said:
You MUST have eaten at least one of them, though. Otherwise how could you say fish taste better. Better than what? And how else could you know?
Click to expand...

i am guessing i have yet to find a place that serves whale or dolphin or what not in my area.
 
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