Living under water is as challenging as it sounds even for seals and dolphins. Every time a dolphin dives its heart goes trough a strange process, that cannot yet be explained.
Deep diving can be life threatening not only for land animals but also for the ones build to live in the water. A research at the University of Santa Cruz, California, discovered that the body of marine mammals is suffering irregular heart beats when diving at high depths.
Two of the species studied for this research have been the bottlenose dolphin and the Weddell seals and both mammals showed signs of cardiac challenges while swimming inside the water.
When diving, marine mammals have to conserve oxygen and for this to happen, their body enters a stage called bradycardia, a process which diminishes the rhythm of the heart beats. The paradox rises when the animals have to increase their speed and exercise, the automatic reaction of the body would to speed up its heart rates, process known as tachycardia.
This slow vs. fast beatings, provoke arrhythmia, an unbalance and irregular heart beating. What really happens inside their body, is still unclear.
Until this discovery, bradycardia in marine mammals seamed a logic reaction of the body, but now the process has to be reanalysed. The heart starts to receive conflicting signals, slower or faster which can cause a certain sensitivity of their hearts, said professor of ecology and evolutionary biology at UC Santa Cruz, Terrie Williams.
Scientists arrived to this conclusion after an experiment on a bottle head dolphin, using a new device that measured its heart rate, the diving depth, the time and frequency of swimming strokes and swimming time. The dolphins were tested in pools and open waters but also on some Weddell seals swimming freely in Antarctica.
Arrhythmia, irregular beatings of the heart have been noted in over 70% of the mammals’s dives. The hearts beats were influenced both by the depth of the water and by the speed and intensity of their movements. Certain times, the heart would alternate very fast between states of bradycardia and tachycardia. This is just proof that not even marine animals are fully adapted the under water environment and the system has flaws, said professor Terrie Williams.
The heart beat contradiction happening inside their system doesn’t necessarily affect their health condition. This research is more the first steps of a broader subject, explaining what happens to diving animals, that get stranded on land.
Similar reflexes with the ones found in dolphins and seals has been found in human heart beats when the body gets in contact with cold water. Swimming in cold water has proved to be the cause of 90% of the deaths among triathletes during the race.
Image Source: The Guardian