DURHAM, N.C. -- If you feel like your metabolism just isn’t what it used to be, no matter how many hours you spend in the gym, dolphins can relate.
It’s the first time scientists have measured an age-related metabolic slowdown in another large-bodied species besides humans, said first author Rebecca Rimbach, postdoctoral associate in evolutionary anthropology at Duke.
Rimbach has studied energy expenditure and other aspects of physiology in animals ranging from mice to monkeys. But data on the inner workings of marine mammals such as dolphins and whales have been scant, she says. That’s because these ocean dwellers are notoriously difficult to recapture for repeat measurements.
The researchers studied 10 bottlenose dolphins aged 10 to 45 living at two marine mammal facilities, Dolphin Research Center in Florida and Dolphin Quest in Hawaii.
To measure their average daily metabolic rate, the researchers used the “doubly labeled water method.” Used to measure energy expenditure in humans since the 1980s, it’s a method that involves getting the animals to drink a few ounces of water with naturally occurring “heavy” forms of hydrogen and oxygen added, and then tracking how long the animals take to flush them out.