An unknown shy whale surprised scientists by staying submerged for about four hours.
Cuvier-billed whales are famous for their ability to dive deep and average about an hour underwater.
But the researchers were surprised when they recorded a single animal dive for three hours and 42 minutes.
They believe it is the longest dive ever recorded for any whale and almost certainly has set a record for all mammals as well.
The species of beaked whales is a bit of a mystery to scientists, as they spend most of their time offshore.
Cuvier’s beaked whale has a stout body, small sloping head and short beak. Males seem to have teeth that they use for combat, and females don’t seem to have any.
They usually hunt squids for food, and they usually suck the critters in their mouths to eat them.
Scientists say that in pursuit of their favorite food, these whales have been documented diving to a depth of nearly 3,000 meters.
When it appears on the surface, it spends about two minutes before diving again, which means that it is very difficult for researchers to notice and mark it.
In 2014, one whale was recorded to dive for just over two hours, the longest known time underwater.
In this latest study, researchers recorded more than 3,600 dives of 20 Cuvier beaked whales over a five-year period.
They recorded dives that lasted from about half an hour to two hours and thirteen minutes, long after the point at which they had to run out of oxygen from an animal of this size.
But two dives by one whale “astonished” the research team.
One was about three hours long, another three hours and 42 minutes long.
“The longest diving time for this species was about two and a half hours, so this is the longest for Cuvier’s beaked whales, but it is also the longest for any mammal,” Dr. Nicola Kwik, of Duke University in Durham, USA, told BBC News. .
While this person has been recorded completing these extremely long dives, Dr. Kwik says her study showed that a large proportion of the animals observed were able to dive for very long periods.
Researchers speculate that the whales may have very slow metabolism, possibly combined with a greater than average oxygen reserve, and an ability to tolerate lactic acid build-up.
“Their body muscles are built differently than you might expect from a deep diver,” said Dr. Kwik.
“They kind of have smaller brains that are very small in the lung. And they have a lot of good muscle tissue that is great for retaining oxygen stores, which probably helps them increase dive times.”
Fear may also have played a role in a standard dive.
This species is at risk from killer whales and great sharks. Whales react to threats to stay underwater for as long as possible, until predators walk away.
The deep dive may also have been a response to humans. The recording was made about 24 days after exposure to the US Navy active sonar signal, and the researchers excluded it from their dataset, as they were likely affected by the noise.
Cuvier’s whales are known to be sensitive to sonar and other experts believe this may have an effect on dive length.
“A dive time recorded of more than three hours is probably not typical,” said Nicola Hodkins of Whale and Dolphin Conservation, who was not involved in the study. “Instead, an individual’s score has been pushed to its absolute limits.”
“Only one whale has been recorded, and it is believed to be already endangered by exposure to extremely high levels of noise from the military sonar and thus exhibiting abnormal behavior, and is undertaking such extreme dives.”
The research team found that there is little relationship between the length of dives and the recovery time whales need before they descend again.
Scientists believe that studying these deep-diving animals could provide some clues to tough questions like cancer in humans.
“There is some interest in working with colleagues in oncology at Duke University, and even with Covid, because that involves cells losing oxygen or being hypoxic,” said Dr. Kwik.
“So, if these whales are in conditions of lack of oxygen in their tissues, and if we can figure out what they are doing, could that have another effect on human health or just the health of the ocean in general?”
The The study has been published In the Journal of Experimental Biology.
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