A new study led by researchers at the University of California, Santa Cruz (UCSC) has found that aquatic mammals need to be large enough to generate enough power to swim through the water. However, they also need to be small enough to avoid overheating.
The study's findings, which were published in the journal "Nature Ecology & Evolution," provide new insights into the evolutionary history of aquatic mammals and the challenges they face in their environment.
"Aquatic mammals are some of the most iconic and beloved animals on the planet," said lead author Dr. Jeremy Goldbogen, a professor of environmental studies and a researcher in the Institute of Marine Sciences at UCSC. "But despite their popularity, we still don't know much about why they need to be so big."
To address this question, Goldbogen and his colleagues analyzed data on the body sizes and metabolic rates of 34 species of aquatic mammals, including whales, dolphins, porpoises, seals, and sea lions.
The researchers found that aquatic mammals need to be large enough to generate enough power to overcome the resistance of the water. This is because water is about 800 times denser than air, so it takes a lot more energy to swim through water than to walk or run on land.
However, aquatic mammals also need to be small enough to avoid overheating. This is because when animals swim, they generate heat through their muscles. The larger an animal is, the more heat it generates, and the more difficult it is for it to dissipate heat.
The researchers found that the ideal body size for an aquatic mammal is a balance between these two opposing forces. Aquatic mammals need to be big enough to generate enough power, but not too big that they overheat.
"This study provides a new understanding of the evolutionary history of aquatic mammals and the challenges they face in their environment," Goldbogen said. "It also has implications for the conservation of these animals, as we need to understand their unique needs in order to protect them."
In addition to Goldbogen, the study's co-authors include Daniel Greenberg, Jeremy Davis, and Allison Parton from UCSC; Robert Shadwick from the University of British Columbia; and Terrie Williams from the University of California, Davis.
