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Why do some fish have a horizontal tail fin

  1. Aug 8, 2005 #1
    What do some fish have a horizontal tail fin,
    while others have a vertical tail fin ?
    Are there some functions that one type performs better than the other...

    if so, what advantages would a vertical tail fin have over a horizontal one?
    What advantages would a horizontal tail fin have over a vertical one?
  2. jcsd
  3. Aug 8, 2005 #2


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    Now, I do NOT know the answer to this, bomba923, but I might perhaps help you a bit:

    If you know what kinds of fish have the one type of tail or the other, and in addition, find that the manner of living of two distinct kinds of fish differs in several ways, can you then relate such differences in living to the distinct tail types?

    That is, both types of fish ought to be optimally suited TO THEIR OWN WAY OF LIVING; so, does one tail type optimize one way of living above another?
  4. Aug 8, 2005 #3


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    Are you sure you're talking about only fish? As far as I know, all fish have their tail fin oriented in the same direction, although the shape can differ from species to species. Other aquatic animals, such as the aquatic mammals (dolphins, whales, seals) have flippers (not fins...fins are bony structures, flippers are appendages analogous to hands and feet) that are oriented horizontally rather than vertically.

    If you really do mean fish, can you provide a link to a description of a fish of each example?
  5. Aug 8, 2005 #4
    I believe most fish have a vertical caudal fin (tail fin), I think only ones that have a horizontal caudal fin are flat fish. This allows them to lay totally flat on the bottom. Young flat fish start their life swimming like other fish (with vertical caudal fin). During their development their body changes: one eye moves to the other side the skeletal system changes, etc. so they basically just rotate 90 degrees and their caudal fin (together with the rest of their body) will be oriented horizontally.

    The only other ones I can think of that have a horizontal tail are mammals like whales and dolphins, but they are not fish.
  6. Aug 8, 2005 #5
    Hmm--actually :redface:, I meant differences in the hydrodynamics of the fishs' movements:
    *For example, whales need to swim to the surface for respiration every now and then; would their horizontal tail fin give them better pitch control for rising/sinking ?
    *Sharks have vertical tail fins--perhaps better acceleration/max velocity or turn control?
    Basically, I was wondering more specifically about the hydrodynamic differences between either tail fin orientation.
    *Do vertical tail fins provide greater yaw control than horizontal ones?
    *Do horizontal tail fins allow great pitch control than vertical ones?
    *What about roll manuevers? Do fish roll? Which tail fin orientation is preferred?
    --or greater max velocity or acceleration?
  7. Aug 9, 2005 #6
    The movement of the tail (and in many species the whole body) is mainly used for propulsion. It does not matter whether it moves up-down or left-right. It is the fins that generally control the direction of movement. Pitch and yaw are mainly controlled by the pectoral fins. The pelvic fins also influence pitch, and body posture can influence yaw (i.e. bending the head to the left will make it move to the left). Most fish cannot bend their bodies in a way to change the pitch (but flat fish obviously can). Fish do use roll motion. The dorsal and anal fin mainly control the roll.

    Of course also the shape of an animal and the shape of its tail and its fins (or flippers or whatever extremities it uses as rudders) are major factors in determining the direction of movement.
  8. Aug 9, 2005 #7


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    The type of movements that a particular fish species has to do are a primary determinant of the morphology of body stucture and fin shape. Fast pelagic cruiser fish like tuna or mako sharks have similar torpedo-like stream-lined body shapes with crescent shaped caudal fins to enable very fast speeds. Eels have elongated bodies with long fins and move in a slower, but efficient wave-like fashion. Check this page for the various body types and movement strategies of fish, (be sure to scroll down the info is rather spread out).
  9. Aug 9, 2005 #8


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    You've already got your answers on movement from others here, so I'll just correct the biology problem here...whales aren't fish! :biggrin: They're mammals.
  10. Aug 10, 2005 #9


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    Recall* that marine mammals evolved from terrestrial mammals. I would guess (without having researched the question) that the horizontal tail fin was an easier adaptation given the orientation of the spine. If you lie on the floor, it's easier/more efficient to move your backside up& down (no jokes please!) than side to side.

    (* - not that you were there personally!)
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