A systematic map and comprehensive database of animal organ sizes

The relationship between individual organ size and overall body size in animals is a fundamental biological phenomenon that spans multiple disciplines and has been studied for decades. However, a comprehensive synthesis of the sources of variation in organ-specific scaling remains lacking, even among mammals, the most extensively studied vertebrate group. To address this, we developed a systematic map and compiled a large database of paired organ and body size measurements. This database includes over 10,000 records from 366 species across eight major vertebrate and invertebrate classes: Aves, Mammalia, Actinopterygii, Reptilia, Amphibia, Chondrichthyes, Insecta, and Cephalopoda. Our database provides size estimates for 53 organ types, categorised into 10 physiological systems, with most data derived from digestive, circulatory and excretory systems. In addition, we include extensive metadata to contextualise the original studies, which highlights gaps—such as the season of animal collection and life stage, both of which were among the least frequently reported. We anticipate this comprehensive and reproducible resource will offer a robust foundation for improving the parameterisation and cross-species applicability of simulation models based on physiological and kinetic principles, thereby advancing our understanding of organ size scaling across diverse taxa.