Why are the flippers of whales horizontal in comparison to tail fins of fish?

Question

Is it faster to be horizontal? Or is it that way because mamals need to come up for air?

Answer 1

The tails of fish and whales are different because they are the result of different evolutionary pathways, not because of direct functional factors. It is in fact an example of what happens when organisms with different structures, abilities and constraints are faced with the same functional requirement.

Fish have relatively simple vertebrae; in most cases, the vertebral centers look like biconcave cylinders that contact each other. This type of vertebrae allow the vertebral column to undulate laterally, and the tailfins of fish have evolved in a vertical arrangement, so that the lateral axial movement of the body moves the tail to provide thrust.

In contrast, the vertebrates that evolved adaptations for life on land, the tetrapods, don't have this type of vertebra any more. Our vertebral bodies are locked together by means of special apophyses (outgrowths). And although lizards and snakes undulate laterally, we mammals have lost that flexibility (as part of a different body structure that allows a different arrangement of lungs for respiration, etc). However, we can flex the spine up and down (or forward and backward, in humans) and many mammals that are fast runners use dorsoventral flexion/extension as part of their locomotion (if you've seen a film of a running cheetah, you know what I mean).

Now, aquatic mammals use their limbs (more or less transformed into flippers) and tail to move in the water. They use the same powerful up-and-down body undulation as their ancestors used on land; in fact, this undulatory locomotion has been documented for a fossil ancestral whale, Ambulocetus (see link).

So in this case, as in many others, we see more than one solution, and all are "optimal" (both are hydrodynamically efficient), but different because their evolutionary paths were just different, not better or worse.

Answer 2

Wow, im sorry to do this, but i just cant take it. whales do not spap the surface of the water to concentrate food and they do not eat plankton, they eat zoo plankton. The orientation of the tail is an artifact of their ancestory. Since they arose from land animals, the musculature and spine were orientated for up and down motion so as the fluke developed, that was its direction. Both verticle and horizontal are equally fast

Answer 3

"Other than marine mammals" is irrelevent because marine mammals are just that - marine mammals - not fish. So they shouldn't be inclusive at all. But to answer your question, the only fish even remotely close to having a horizontal tail would be the flounder relatives which, as you've already pointed out, are really only swimming sideways.

Answer 4

there are plankton eaters that have vertical tails, like the whale shark which is a fish...There are mammals that have horizontal tails that eat fish and even other mammals, like the orca, so it has little to do with eating habits. The horizontal flukes do make diving and breaching more efficient, but I think only our maker truely knows the answer.

Answer 5

The tail is horizontal because it allows the whale to swim with little resistance. Their tail fins are called flukes which move up and down. In order for it to move up and down the shape is therefore horizontal.

Answer 6

Fish are evolutionarily old, the side to side is primitive like a lizard... ...Mammals are a new design like a cheetah, look how the spine goes up and down like a dolphin or whale. Whales came from land mammals.

Answer 7

Actually it's because many whales eat plankton. They use the flat horizontal part of their tail to slap the water, which somehow concentrates the plankton in one place. Then they swoop around and strain the plankton out of the water. So, the horizontal tail is for slapping the water to gather food.

Answer 8

It's because dolphins and whales are mammals and swim moving their body up and down.... whereas fish and sharks swim side to side- therefore tail fins are vertical.

Answer 9

When fish emerged onto land, they gradually switched from side to side gait to up and down gait, which is more efficient on land. When Mammals returned to the sea, they preserved this up and down motion. It has been said that dolphins "gallop through the seas".....very poetic in my opinion. It has to be one way or the other, and to me it is not surprising that nature has produced both ways, (side to side and up and down). The same sort of situation happened way back in the precambrian age. Did you know that Molluscs like clams and oysters open and close their shells "up and down" whereas brachiopods open their nearly identical looking shells "left and right" or "side to side"? As Mr Spock might say, "Fascinating!".

Answer 10

It is an evolutionary relic. Whales and dolphins are marine mammals and developed from ancestors with a mammalian pelvis and hind legs.

Hind leg pairs on mammals are side by side, not one in front of the other.