A comparative study of the energetics of 165 animal species, including representatives of most large phyla and of all 13 chordate classes, reveals a very wide range of specific somatic maintenance costs, when corrected for a common temperature. While a typical value is 20 J d−1 cm−3 at 20°C, some vertebrates have values below 10 J d−1 cm−3 and some small invertebrate planktivores have values exceeding 1 kJ d−1 cm−3; the salp Thalia seems to have around 8 kJ d−1 cm−3. This wide range of values is amazing because some 80–90% of the somatic maintenance costs is generally thought to be used for the turnover of mass and animal species do not differ that much in chemical composition in terms of proteins, lipids and carbohydrates. I present theory-based arguments to suggest that species waste resources for the purpose of remaining small, growing fast, and responding rapidly with population numbers to temporal and local food abundance.