Fastest heartbeat in a mammal

The shrew (family Soricidae) has the fastest heartbeat of any mammal, with a rate of 1,200 beats per minute, which is similar to that of a hummingbird's when hovering.

Shrews are roughly the size of a thumb and weigh about 4.5 g (0.15 oz). Their diet is composed almost entirely of invertebrates, although they are known to also eat rodents, amphibians and reptiles, and even other shrews. Some types of shrews are active day and night and eat many times their own body weight in one day. They have been seen attacking pray larger than themselves.