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 ^_^

sciforums in 02 (http://www.sciforums.com/showthread.php?t=10394)

sciforums in 06 (http://www.sciforums.com/showthread.php?t=53866&highlight=aquatic)

definite improvement, ja?

fish taste better

fish taste better

Are you really, really sure about that? :D Just how many servings of aquatic mammals (seal, whale, porpoise, sea turtle, etc.) have you eaten? ;)

fish taste better

I had whale carpaccio this summer I assure whale is frikkin' delicious, everyone should eat whales and drive 4x4s.

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.)

heh

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.

aquatic mammals (seal, whale, porpoise, sea turtle, etc.)
The turtle is a really weird mammal :D

The turtle is a really weird mammal :D

Heh! :D True!! ;)

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....

....
flatfishes ( flounders, sole, halibut etc) ... have done some serious body realignment over the years to facilitate this.... 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.

Are you really, really sure about that? :D Just how many servings of aquatic mammals (seal, whale, porpoise, sea turtle, etc.) have you eaten? ;)

i try not to eat things that are intelligent.

i try not to eat things that are intelligent.

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?

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.

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?

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

I wanna know how in the heck penguins turn on their torpedo mode and shoot super fast straight outta the water like this such as at 3:17. That's some turbo!

http://www.youtube.com/watch?v=o9I5g9nJdKM

- N

I wanna know how in the heck penguins turn on their torpedo mode and shoot super fast straight outta the water like this such as at 3:17. That's some turbo!

http://www.youtube.com/watch?v=o9I5g9nJdKM

- N

this is called "porpoise"

http://www.seaworld.org/animal-info/info-books/penguin/images/pic-adelies-exiting-water.jpg

a result of wing and breast muscles movement



please refrain from cursing. ty

heck

please refrain from cursing. ty

???

a result of wing and breast muscles movement

Thanks. They'll always remind me of lil torpedos though. :D

- N

Sorry Gustav, didn't mean to lose you with the vernacular

loved it fool

The physicists tell us that the more advanced an aquatic animal is, the more efficient a swimmer it is.

The earliest vertebrate swimmers, like lampreys, wriggle rather inefficiently. Sharks move a good portion of their bodies. Bony fish, though, just move their tail, keeping the rest of their body rigid. Supposedly, this reduces the energy cost of moving through a liquid.

Why don't the other fish swim like th ebony ones do? Presumably because you need bones to do it. I don't know what any of this has to do with dolphin tails, though.

...Bony fish, though, just move their tail, keeping the rest of their body rigid. Supposedly, this reduces the energy cost of moving through a liquid. ...have you ever seen a water snake swim? I am not sure, but think the most efficient swimmer would be the ones that give the least energy to the water. Surely there are large eddies made by a "wagging tail" but the traveling wave a water snake makes appears to resemble and be as efficient as a rack and pinon gear. I.e. hardly inparts any motion to the water.

have you ever seen a water snake swim? I am not sure, but think the most efficient swimmer would be the ones that give the least energy to the water. Surely there are large eddies made by a "wagging tail" but the traveling wave a water snake makes appears to resemble and be as efficient as a rack and pinon gear. I.e. hardly inparts any motion to the water.

But it loses TONS of energy to moving as much back and forth as it does forward.

Bony fish are wonderfully successful creatures; the assumption is that they are better at swimming than their ancestors, who lacked bones.

Dolphins may be able to get away with swimming less efficiently, but more powerfully, because as air breathers, they're not confined by the extremely low levels of O2 in water.

I read that dolphins & co. originated from land mammals.Mammals originated on the land so the marine mammals have to have evolved from them. We always wondered which land mammal wandered out into the sea and decided to stay there. DNA analysis gives the answers. The pinnipeds (seals, walruses, etc.) are members of the order Carnivora, with the felines, canines, bears, hyenas, weasels, etc. It turns out that the cetaceans (dolphins and whales) are members of the order of artiodactyls (even-toed hooved mammals) with cattle, deer, goats, antelope, camels, pigs, etc. Their ancestors were primitive hippopotamuses who swam all the way down the river to the sea and liked what they found there.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).Cetaceans have a vestigial pelvis. Specifically, they have some fragments of a pelvis that float out in their flesh, not connected to any other bones. The pelvis has two main functions. Support, which is unnecessary when water distributes the weight over the entire lower surface of the body; and anchoring of the legs, which is unnecessary if you ain't got no legs.i am guessing i have yet to find a place that serves whale or dolphin or what not in my area.You may have to go to Japan for that.I wanna know how in the heck penguins turn on their torpedo mode and shoot super fast straight outta the water like this such as at 3:17.Penguins are the avian equivalent of... well not dolphins but seals. They can still barely live on land and in fact have to go there to breed. But they're much better adapted to water.

Interesting to ponder whether a fully aquatic bird could evolve. The cetaceans give birth in the water and then push the baby to the surface for his first breath. Whatcha gonna do if your baby is growing inside an egg instead of inside you? Where do you lay the eggs so you can protect them but still breathe?Why don't the other fish swim like the bony ones do? Presumably because you need bones to do it.It may be vice versa. They're called cartilaginous fishes because their skeletons are composed of cartilage, which is softer than bone. Perhaps the more rigid skeleton of the true fishes does not allow them to bend that way.

It may be vice versa. They're called cartilaginous fishes because their skeletons are composed of cartilage, which is softer than bone. Perhaps the more rigid skeleton of the true fishes does not allow them to bend that way.

My presumption was that since swimming more efficiently is advantageous, everyone would want to swim efficiently. However, since the cartilaginous ones don't, there must be some reason, yes? We'd likely see some sort of convergent evolution where sharks evolved the same swimming pattern of bony fish, since it's better. But we haven't- sharks move almost half their body in propelling themselves.

There are many instances where very different organisms evolved analogous structures, though without sharing a common ancestor for hundreds of millions of years. Yet often, we also see certain things failed to be evolved, simply because the exaptations aren't conducive to further modification, or lacking completely.

I was also assuming sharks would want to swim like bony fish, given that bony fish are what, an order of magnitude more successful than the cartilaginous ones?

Interesting to ponder whether a fully aquatic bird could evolve. The cetaceans give birth in the water and then push the baby to the surface for his first breath. Whatcha gonna do if your baby is growing inside an egg instead of inside you? Where do you lay the eggs so you can protect them but still breathe?

An ovoviviparous avian?

But it loses TONS of energy to moving as much back and forth as it does forward....I do not think nearly as much as the eddies that roll off the sid's of the fishes tail as this motion of the water is OCSILLATORY AND STREAMLINED FLOW. - sort of like a pendulum swinging. Consider any water molecule. First it swings to the right and then half a cycle later it is swinging to the left. In oscillatory motion the disipation can be quite small - that is never true of motions that induce eddies.

You can even see this in humans swiming to a slight extent. Although I do swim routinely I never did competively. Thus, not sure of the name of the stoke, but a couple of years ago, someone set new records by a new technique in that stroke. Previously one dove in and quickly surfaced to start doing the "breast stroke," I think it is. He took advantage of the fact there was no time limit on how long you can swim under water following the initial dive in. He did undulate his body, sort of snake like but vertically, nearly to the far end of the pool before surfacing to do one or two "breast strokes." - I do not know if the rules have changed to disallow this now. Perhaps there is a note by his record setting invention. - Clearly more efficient use of "oscillation of water" than the disipation of the breast stroke's splashes and eddies. (Swimming almost any stroke at record setting levels is mainly limited by the sustained power the swimmer can produce and the efficiency of his tecnique. I doubt if he was the most powerful swimmer EVER in the pool - just the most efficient one - when he set the world record)

...You may have to go to Japan for that.{whale meat dish}... Any major city's best restraurants in Norway also, I think. My first wife was Norwegian. I ate some in Bergan once, but other than noting that it is red meat, I did not find anything that I can now remember notable about it. Bergan is on the West Coast and it was not expensive there I am sure (I would not have ordered it if it were.)

Some Inuits along the Artic Ocean eat a lot whale. I don't think they can sell it, though: you'd have to be invited to dinner.

My guess is that it's good food, and the destruction of the whales for oil was the equivalent of stripmining Iowa topsoil to get at some coal underneath.
Interesting to ponder whether a fully aquatic bird could evolve Loons are pretty close. They build floating nests, basically cannot walk.
We'd likely see some sort of convergent evolution where sharks evolved the same swimming pattern of bony fish, since it's better. But we haven't- sharks move almost half their body in propelling themselves. Depends on the shark - there are some very fast sharks.