how can dolphins swim but never get tired if they are mammals and share a similar development to ourselves ?

Question

it's just puzzling me that if they can evolve muscles simliar to the heart muscle which never get tired for their whole body, why didn't a land animal also go down that evolutionary process? Even wild dogs and wolves get tired, so unlimited stamina must be desirable.

Answer 1

Dolphins rest just like any other mammal. But remember that water supports the body weight so less effort is required to continually swim through water than is required to walk or run.

It also depends on the rate of exercise they do - dolphins have a natural "cruising speed" that they can keep up almost indefinitely but they're not able to sustain bursts of high speed for hour after hour. This cruising speed means that the muscles are able to function at that rate all the time because the body is able to supply them with oxygen and glucose (for energy) at the same rate that it is used up. If high speed is required the extra energy needed is produced by the partial metabolising of glucose to form lactic acid. This works fine for a while but the lactic acid builds up in the body and you get that "tightening of the muscles" feeling. Afterwards you must use extra oxygen to burn the lactic acid completely which is why you are out of breath. Athletes train regularly to increase the flow of oxygen to their muscles so that lactic acid build-up starts later and can then be broken down more rapidly - this is part of improving what we call "stamina".

Dolphins and most other sea-living mammals have evolved very efficient body systems to enable them to take more oxygen in to their bodies and use it more effectively and this also improves their "stamina".

Most mammals have this natural cruising speed: Humans are more than capable of walking at a steady pace for 12 hours at a time - walking is our "natural" means of getting along and given sufficient food and water (and rest for a few hours) we can do it day after day. The same basic principle applies to dogs, wolves, horses etc etc

Answer 2

1

Answer 3

they have skeletal muscle just like land animals. However they have increased aerobic ability in the muscles used for swimming, to withstand hypoxia on diving. They have 10% more mitochondria and associated chemicals; and increased myoglobin concentrations. This gives them the ability to produce more energy. Cardiac muscle is completely different in its structure and unsuitable for voluntary control as it is highly branched with intercalating discs that transmit a uniform electric pulse to enable continual and synchronous contraction.

Answer 4

Dolphins do get tired, they simply shut down half of their brain when they sleep so they still can go up for air and watch for predators.

Answer 5

Muscles develop to suit lifestyle. If you spent every day running for miles from you learned to walk, you would soon be able to run constantly, provided you had some way to feed while you ran.

Answer 6

They do sleep, but only with one half of their brain at a time. Their brains are structured so they can essentially shut down one half of it at a time while the other half remains active . . . while this happens they may display some sluggishness but they're still awake.

Answer 7

dolphins do get tired and do sleep they live in big groups called pods, so half the can rest /sleep while others keep guild so they,re not attacked they can also switch off half their brains.

Answer 8

their brain rests during sweaming his half brain rests while another works then he can replace and give rest another half spere of the brain but he can work with the whole brain in dificulties and in nececities. and his muscules are developed like this that he can rest during work if its'nt loaded heavily. that's why he can work 24 hours and not sleep at all.

Answer 9

You weigh a lot less in water and all animals adapt to their usual environment. You don't see dolphins climbing ladders.

Answer 10

i think its something to do with the fact that they shut one half of there brain down when they are sleeping but can still swim and are aware of any dangers that are around them, i could be wrong about this tho!