At northern latitudes the garter snake (Thamnophis sirtalis parietalis) undergoes a prolonged period of hibernation and has access to food only from mid-May to mid-September. An examination of seasonal changes in the body composition of this organism revealed that protein and ash, expressed as percentage of total body weight, remain essentially constant throughout the year. Lipids are low in the spring, increase during the summer, and decrease during the autumn and winter. Percentage water content exhibits a pattern which is the reverse of that of lipids, with the exceptions of a dehydration in the autumn and a rehydration in the spring. Expressed in absolute terms, for an animal of fixed body length, ash remains relatively constant throughout the year, while all other components show a seasonal pattern similar to that of lipids. The data suggest that the animals are near starvation in May, at the end of an 8-month aphagic period. The period of aphagia and low winter temperatures appear to be the most important factors causing seasonal changes in body composition.
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文章 : 英语