Pulse Rate, Metabolism, Size... & more Hearty facts

A faster heart and a faster metabolism too! Smaller animals use more energy for their body mass to maintain their body temperature ...because they lose heat faster than larger animals.
Birds	Mass (grams)	Pulse Rate (beats/minute)
canary pigeon  crow  buzzard wild duck  hen  domestic duck  turkey	20  300  341   658  1100  2000   2300  8750	1000  185  378  300  190  312  240  193
The Heart of an ELEPHANT weighs between 40 and 60 pounds and beats about 30 times a minute. Check this out! Compare the heart beats of a mouse, human and elephant. Larger animals have larger hearts too, and they are connected to large veins and arteries.    The large hearts can generate great pressures while pumping blood, and due to the sheer quantity, increasing the risk of harming the blood vessels. It also takes longer for the pressure to push the blood to limbs 'far' away, and therefore increasing the pulse rate would not really serve its purpose.
Mammals	Mass (grams)	Pulse Rate (beats/minute)
mouse  rat  guinea pig  rabbit   small dog  large dog   man  horse	25  200  300  2000  5000  30000  70000  450000	670  420  300  205  120  85  72  38
Want to see how this is figured out?... Click Here.

Why do smaller animals have faster heart rates? Smaller animals are constantly on the lookout for danger and must be able to react quickly when they need to. A fast heart and breathing rate ensures that enough oxygen is being put into the bloodstream to allow the animal to move quickly without getting tired, or eaten. Also, because the animal is smaller, it doesn't take the blood very long to travel one loop around the circulatory system, as it might if it were an elephant or a whale. The circulation is therefore quicker allowing the heart less time to relax in between pumps.