Upper limits to body size (from left to right):

A groundbreaking study undertaken by researchers from the University of Pretoria’s (UP) Faculty of Veterinary Science has revealed that the heart operates with declining energy efficiency as body size increases among mammals.

The 20-tonne extinct giant hornless rhino, Indricotherium, is one of the largest known land mammals to have existed; 70- to 100-tonne gigantic sauropods, such as Brachiosaurus, were the largest known animals to have walked the Earth; a very brave 60kg human for scale; the six-tonne African bush elephant is the largest land animal alive today. .

A magnified image of cardiac tissue captured from the heart of a wild African antelope: the common duiker (Sylvicapra grimmia), showing the close functional relationship between the capillaries that supply fuel and oxygen (17 large tubular profiles flushed of blood) and mitochondria that consume fuel and oxygen (numerous dark-stained structures). (Credit: EP Snelling, with permission.)

How the densities of capillaries and mitochondria in the wall of the heart change across five orders of magnitude: Showing body weight among mammals, from shrew to elephant. (Credit: EP Snelling, with permission.)

Composite showing a magnified image of cardiac tissue where fuel and oxygen enter the cells: An image of the heart pump that pressurises the blood; phylogeny of species used in the study; and the body size relationships of the capillaries and mitochondria (as a proxy for metabolic power) and mechanical power of the heart. (Credit: EP Snelling, with permission.)

the common duiker (Sylvicapra grimmia), showing the close functional relationship between the capillaries that supply fuel and oxygen (17 large tubular profiles flushed of blood) and mitochondria that consume fuel and oxygen (numerous dark-stained structures).
Showing body weight among mammals, from shrew to elephant.
An image of the heart pump that pressurises the blood; phylogeny of species used in the study; and the body size relationships of the capillaries and mitochondria (as a proxy for metabolic power) and mechanical power of the heart.

Researchers

Prof Edward Snelling

Dr Edward Snelling did his undergraduate studies at the University of Adelaide, Australia and joined the University of Pretoria’s Faculty of Veterinary Science in February 2019.

His research is at the interface of experimental physiology, biomechanics and biochemistry. He uses models from Africa and Australia to study resting and locomotor energetics, respiratory and cardiovascular performance, muscle and skeletal systems, and thermoregulation in mammals, birds, fish, and insects. More information here -> www.edwardsnelling.com

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