Body weight of animals and their functional and population characteristics.

Abstract

Numerous studies showed that many body functions, particularly, the main ones, such as the rates of metabolism, nutrition, growth, and excretion and the number of offspring, are related to the body weights of the organisms. The inherent rate of population growth, a key species-specific population characteristic is also related to the body weight of animals of different species [11]. Numerous data of this type accumulated in the literature allowed broad generalizations by expressing the dependences of the functional characteristics of individuals and populations of different species on the animal weight using allometric (power) equations [1, 2, 5, 7, 10‐12]. The rate of animal growth is tightly related to the rate and intensity of metabolic processes. The most substantial characteristic and widespread measure of the rate of metabolism in animals is the oxygen consumption rate. The rate of metabolism per unit body weight represents the metabolism intensity (the specific metabolic rate). A decrease in the metabolic rate upon an increase in individual weight of animals is an important principle common for all animals. For many poikilothermal and homoiothermal animal species, it was shown that the dependence of the rate of metabolism on body weight may be expressed by a power equation with an exponent of 0.75, which was determined with a very small error of the mean [12]. Further studies performed with different groups of animals made it possible to determine the exponent for each group, which in most cases were not statistically different from 0.75 and which confirmed the power dependence of the oxygen consumption rate on the animal weight, common for all animals. In the case of poikilothermal animals differing in weight by ten orders of magnitude, the dependence of the oxygen consumption rate ( Q ) on the weight ( W , g wet weight) may be approximated by the following equation [12]: