A new study has showed that the bottlenose dolphins and Weddell seals have to suffer from irregular heartbeats or high frequency of heart arrhythmias while they undergo their deepest dives.
According to the researchers, these marine mammals have to face this physiological challenge despite having remarkable adaptations to aquatic life.
Lead study author Terrie Williams, professor of evolutionary biology and ecology at the University of California-Santa Cruz, said, “This study changes our understanding of bradycardia in marine mammals. We are not seeing lethal arrhythmias, but it is putting the heart in an unsteady state that could make it vulnerable to such troubles.”
Bradycardia is a marked lowering of heart rate in aquatic mammals.
The study group found that the heart rates of these marine diving animals differed with depth and exercise intensity, sometimes alternating instantly from periods of bradycardia and tachycardia.
Cardiac arrhythmias took place in over 70 percent of deep dives. It is believed that the marine mammals are completely adapted to aquatic life.
“In terms of the heart rate and dive response, it is not a perfect system. Even 50 million years of evolution has not been able to make that basic mammalian response impervious to problems,” Williams said.
The new findings have effects for efforts to comprehend the stranding events that involve deep-diving marine mammals like beaked whales.
The result is expected to be relevant in case of humans too. The dive response of mammals, also called dive reflex, also occurs in humans and other terrestrial animals. Scientists explain it is triggered when the face is in contact with the cold water.
The study’s findings were published online in the journal Nature Communications.