The smaller warm-blooded animal, the stronger must be its metabolism to maintain a constant body temperature. The smallest tetrapods Etruscan shrew is no longer than 4 cm and a weight of about 2 grams to obtain a sufficient amount of energy this small animal has to eat per day to 6 times its own weight. At the same time the heart of the Etruscan shrew beats with a frequency of 1500 strokes per minute.
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