Natures wonders: beluga whale breath holding (Introduction)

by David Turell @, Friday, September 23, 2016, 01:33 (815 days ago) @ David Turell

They have extra stores of myoglobin in their muscles, a protein that resembles hemoglobin closely and can hold large stores of oxygen as a result:

https://www.newscientist.com/article/2106782-how-baby-beluga-whales-dive-deeper-and-lon...

"...belugas, one of only three whale species that live in the Arctic year-round.
Their life amid the sea ice means the young whales do swim wild and free - from an early age, baby belugas must follow their mothers under the sea ice, where air holes are transient and scarce.

"Now we are learning how baby belugas achieve that: they are born with more mature diving muscles than any other marine mammals studied so far and they develop more rapidly over their first year of life.

***

"They found that belugas are born with much higher stores of myoglobin, an oxygen-binding protein, than other cetaceans (whales, dolphins and porpoises), making them better prepared for diving at birth than other species. Myoglobin allows oxygen to be stored and slowly released if an animal needs to hold its breath.
The researchers showed that myoglobin in baby beluga whales increased by some 450 per cent between birth and their first birthday, to levels similar to those of fully grown adults. In fact, belugas have adult levels of myoglobin in their muscles by 14 months of age.

"It means belugas are in some respects mature before they wean. That is unique among cetaceans, whose muscles mature after weaning, typically between 2 and 3 years of age.
This, in theory, would allow young belugas to double the amount of time spent under water within a year of their birth, the researchers say. They calculate that both the dive length and depth increased dramatically over the first year of life, from 3.6 minutes and 216 metres at birth to 8.5 minutes and 512 metres.

"It's an “extraordinary result”, says Jeremy Goldbogen, a comparative physiologist at Stanford University in California. “It significantly increases our understanding of how these animals cope with living in environments that require extreme physiological adaptations such as prolonged breath-holds to find food and avoid predators.”
Using this new data on the physiology of beluga's muscle tissue, the researchers then calculated how long adult belugas could hold their breath.

"They found that an adult male and female can hold their breath for a maximum of 13.6 and 12.5 minutes respectively, allowing them to dive to 812 and 755 metres deep. Observations in the wild confirm that belugas are diving to these depths."

Comment: Since myoglobin is a standard constituent of all vertebrate muscles, this is a logical evolutionary adaptation to the deep diving required in the Arctic.


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