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When sperm whales need a nap, they take a deep breath, dive down about 45 feet and arrange themselves into perfectly-level, vertical patterns. They sleep sound and still for up to two hours at a time between breaths, in pods of five or six whales, possibly for protection. No one knew whales slept vertically until a 2008 study documented this behavior. And no one captured really good photography of it in the wild until 2017. 12 comments
@theantlady They’re sleeping after the in-breath, so between one breath and the next. Five hours minimum. It’s why they’re able to go as deep as they can when they dive to hunt. @semiotic_pirate https://royalsocietypublishing.org/doi/10.1098/rstb.2020.0219 Actually, I take that back, I can only read the abstract right now but this older academic review article suggests longer-diving mammals generally exhale. It's an older article though so the answer might be more complicated now. https://www.sciencedirect.com/science/article/abs/pii/0034568783900725 @theantlady I found this. I think they take a breath in to super oxygenate the blood and muscles then compress the lungs to prevent gas exchange. And I was wrong about the time they can be submerged during an active deep dive. More like 20 minutes to an hour in full activity mode. https://www.scientificamerican.com/article/how-do-deep-diving-sea-cr/ Right, so, the general thinking is deep diving mammals spend a period at the surface engaging in gas exchange to replenish oxygen stores in tissues (and remove carbon dioxide). Then there isn't an advantage, and if anything, there's a disadvantage, to filling the lungs with air at the start of the dive. I think this detail has stuck with me because it's surprising compared to how humans typically dive. But we don't go very deep (without scuba gear!) and we don't have as dramatic of circulatory changes as the marine mammals do. |
Gregory's Server
It’s not entirely weird that they move horizontally and sleep vertically when you consider that we move vertically and sleep horizontally.