page_title: Jarman-Bell principle
hierarchical_section_title: Jarman-Bell principle
caption_attribution_description: English: The Jarman-Bell Principle showing the relationship between food (quality and quantity) and animal size.
context_page_description: The Jarman-Bell principle, coined by P.J Jarman and R.H.V Bell, is a concept in ecology offering a link between a herbivore's diet and their overall size. It operates by observing the allometric properties of herbivores. According to the Jarman-Bell principle, the food quality of a herbivore's intake decreases as the size of the herbivore increases, but the amount of such food increases to counteract the low quality foods.
  Large herbivores can subsist on low quality food. Their gut size is larger than smaller herbivores. The increased size allows for better digestive efficiency, and thus allow viable consumption of low quality food. Small herbivores require more energy per unit of body mass compared to large herbivores. A smaller size, thus smaller gut size and lower efficiency, imply that these animals need to select high quality food to function. Their small gut limits the amount of space for food, so they eat low quantities of high quality diet. Some animals practice coprophagy, where they ingest fecal matter to recycle untapped/ undigested nutrients.
  However, the Jarman-Bell principle is not without exception.
context_section_description: The Jarman-Bell principle, coined by P.J Jarman (1968.) and R.H.V Bell (1971), is a concept in ecology offering a link between a herbivore's diet and their overall size. It operates by observing the allometric (non- linear scaling) properties of herbivores. According to the Jarman-Bell principle, the food quality of a herbivore's intake decreases as the size of the herbivore increases, but the amount of such food increases to counteract the low quality foods.
  Large herbivores can subsist on low quality food. Their gut size is larger than smaller herbivores. The increased size allows for better digestive efficiency, and thus allow viable consumption of low quality food. Small herbivores require more energy per unit of body mass compared to large herbivores. A smaller size, thus smaller gut size and lower efficiency, imply that these animals need to select high quality food to function. Their small gut limits the amount of space for food, so they eat low quantities of high quality diet. Some animals practice coprophagy, where they ingest fecal matter to recycle untapped/ undigested nutrients.
  However, the Jarman-Bell principle is not without exception. Small herbivorous members of mammals, birds and reptiles were observed to be inconsistent with the trend of small body mass being linked with high-quality food. There have also been disputes over the mechanism behind the Jarman-Bell principle; that larger body sizes does not increase digestive efficiency.
  The implications of larger herbivores ably subsisting on poor quality food compared smaller herbivores mean that the Jarman-Bell principle may contribute evidence for Cope's rule. Furthermore, the Jarman-Bell principle is also important by providing evidence for the ecological framework of "resource partitioning, competition, habitat use and species packing in environments" and has been applied in several studies.
caption: Expected characteristics in large and small animals tabulated according to the Jarman- Bell principle. Image by Steven J. C. Gaulin.[6]
exif: {}