As climate change and human development continue to encroach on animals’ territories, mass migrations will become more and more common. But animals aren’t all equally able to travel long distances at speed. In general, larger animals are faster than smaller ones. But a new study shows that there’s another important factor in an animal’s top speed: heat dissipation.
By studying the characteristics of over 500 animals that walk, fly, and swim, the team found that animals were limited in their speed by how well they could dissipate heat. This makes sense, even from a human perspective; we may be able to run long distances, but once we’re too hot, we have to slow down. The same principle holds for animals, and the bigger the animal, the longer it takes to dissipate heat. As a result, the team found that the fastest animals over long distances all have intermediate body mass. At their size, they can balance the mechanical ability to produce speed with the thermodynamic requirement to dissipate heat. (Image credit: N. and Z. Scott; research credit: A. Dyer et al.; via APS Physics)