Why a mouse has a higher heart rate than an elephant?
474982
the mouse's heart beats at a higher rate because its metabolic rate (which is measured by the amount of oxygen consumption) is much higher than the elephant's. so, it needs more energy (this case oxygen) to survive, so the heart has to work faster to pump the blood that carries the oxygen through the body for its cells to utilize.
104414
Cruel experiments on mice were done decades ago where the mice were kept awake and died after 23 days. The muscles just can't take it, the heart cannot keep up. In sleep the heart slows and less stress on the diaphram. In humans severe mental illness can be caused by no sleep. In fact, there have been cases of people having halucinations due to severe sleep deprivation. But it is not believed that a person would die like mice from no sleep. Ordinarily a person would just sleep where they stand if it came down to it, or collapse on the floor, wherever they are.
205523
The heart rate would slow to conserve energy also each heart beat would be more efficient due to vasoconstriction of the extremities. At very low temperatures the body starts to decide which parts are more important than others to keep alive. It all comes down to the brain and the heart.
670247
Well, sleep is a period of regeneration.  Sleep deprivation, leads to decrease of brain metabolic activity, weakening of the immune system (i.e. drop in white blood cell count).  And in children the growth hormone is released during sleep.  Generally during sleep the rate of production in cells increases and their rate of protein breakdown decreases. \nInterestingly i can't remember where i read this, but the amount of sleep required for a species depends on their metabolic rate, and the metabolic rate increase as the size of the animal decreases.  So a mouse needs around 18 hours of sleep to regenerate properly, whereas an elephant needs around 3. But don't quote me on those numbers.
355902
The bull has a hump between its head and shoulders. Has more meat than fat. A Very solid animal. and suvives better in hot areas.
127838
Haha... Most living things change their behaviour when exposed to loud music. My dad does all the time.\n\nLoud music plays havoc on the ears, imagine a tiny mouse ear. Plus listening consumes energy... so mice are into some big hell when under such environments.
851463
animal cells are smaller and more numrous
760211
I have just read some of the answers and some are unbelievable. Animals don't think?? Now that is really silly.  As to the question there are recorded incidents of animals with higher intelligence such as the great ape species taking some sort of retaliatory actions as acts of revenge and I have heard that elephants will do so and they do have excellent memories.  Dolphins are also very intelligent so maybe they do so as well but I don't think anyone has recorded this
336206
http://www.bio-lynx.com/RAT-MOUSE.htm\n\nThe Kent system obtains reliable readings by using an occlusion cuff that is separate from the ultra-sensitive piezoelectric pulse sensor. The cuff and sensor are free to move with the tail, even if the animal should  roll over. This makes the system more immune to noise and artifact.\n\nDifferent prices at this site.
898350
Actually, "smarter" mammal have larger brains in ratio to the size of their body.  If you were to take the ratio of size/weight of a human brain and his body and compare that with an elephant, you would find that a human's ratio is much higher.  I've heard contradicting theories with regard to actual percentage used.  We do in fact use most areas of our brain.  Why other areas are not in use probably have to do with evolution.  What sets us apart from other mammals is the amount of things we create for comfort and not survival.  All animals, there may be case by case exceptions, operate under the need to survive.  We operate under what is comfortable.
406313
There not afraid of mice
411983
It's not just humans - most mammals (and other animals to a lessor extent) have emotions.  They serve many key functions for survival:\n\nThey give a reason to act.\nThey give a reason for animals to attract each other.\nThey imprint important experiences in the brain.\nThey help animals make decisions.\n\nThere's probably more, but that's a good start.
291676
That's a great question!\n\nMy first thought was No, but I googled and found a great piece on worm hearts (see link below).\n\nIt turns out they have something that does a similar job, but is not a heart like we mammals have. Follow the link below for all the details.
615888
Pretty much anything that is smaller or slower than a lion. This does exclude rhinos, hippos, end elephants.
1179916
on account of the thick mane, the lion has a slightly reduced chance of throat injury, and both animals use that as a natural target. With equal weight, and a large mane, I would give the lion just a slight edge. \n\nsupport the commuter revolution: http://www.hallisystem.bravehost.com
915230
The heart itself has an internal clock of when it contracts.  However, it is influnced by the autonomic nervous system, in that the sympathetic nervous system increases heart rate, and the parasympathetic system DECREASES heart rate.  Under normal conditions, the parasympathetic system is in more control of heart rate.  When you eat, parasympathetic control is EVEN GREATER.\n\nSo eating slows down your HR.
608407
I agree, you even see this in animal behaviour. Animals like elephants take care of their young and only kill when in danger, or when they feel danger. Elephants normally don't kill humans but because of lots of poachers, they do now. Elephant’s memories are apparently very good. We are of course much more evolved than elephants.