• Body Size Matters in the Lives of Organisms

• # Fulltext

Permanent link:
https://www.ias.ac.in/article/fulltext/reso/026/01/0061-0071

• # Keywords

Body mass, body size, gravi-tational and cohesive forces, inertial and viscous regimes, Kleiber’s rule, metabolic rate, metabolic theory of ecology, surface area/volume relation.

• # Abstract

Body size, arguably the most important attribute of all organisms in the living world, is a reliable predictor of their physiological rates and life-history attributes. Metabolic rates of all organisms ($MR$) are related directly to their body mass ($M$) as an allometric function $MR = \alpha M \frac{3}{4}$ (Kleiber’s rule). The high, mass-speciﬁc metabolic rates of small animals can be accounted for by their high surface area/volume ratios. The much-discussed ‘metabolic theory of ecology’ is essentially an expansion of Kleiber’s rule equation to include two additional metabolism-inﬂuencing factors—temperature and resource availability—with a more generalized quarter-power exponent. According to this theory, many physiological rates, life-history traits and ecological processes follow quarter-power scaling laws. Living organisms must also obey the laws of physics. The relative importance of diﬀerent physical forces to the organisms living on land or in water is also dependent on their body size.

• # Author Affiliations

1. 19 Shakti Apartments Phase-III, Ashok Vihar Delhi-110 052, India.

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