While it may look as simple as sticking a GoPro into the water, capturing videos of marine animals in the Antarctic is no easy feat. Postdoctoral student Kaitlin Allen and her Woods Hole Oceanographic Institution (WHOI) can’t watch what they’re filming in real time, so the team has no idea what is being recorded until they pull the device back out and connect it to a laptop, Allen tells Popular Science.
Sometimes the footage doesn’t capture anything important. Other times, however, it records crucial animal dynamics rarely witnessed by humans. A recently released video Allen and colleagues captured in 2015 (under the proper permit) is one such example. The series of remarkable and admittedly adorable clips featuring a chunky Weddell seal (Leptonychotes weddellii) mother and her pup swimming beneath thick sea ice, occasionally popping their heads through a breathing hole.
“It’s a swimming lesson, essentially,” Allen explains. “Lots of marine mammals don’t teach their pups to swim, seals especially. They nurse them for a bit, and then they wean them, and then the pup is on their own to figure it out. But Weddell seals in the Antarctic do.”
Baby seal swim lesson
The species represents Earth’s southernmost breeding mammal. They are extraordinary divers, who can hold their breath for over an hour. However, since pups are born on the sea ice, they must develop their diving skills over time. In the footage, the mother seal encourages this by waiting for her pup in the water, who will ultimately follow in search of her milk.
“They’re not doing much, but this pup is for the first time having to hold its breath in the water and learning to navigate the sea ice,” says Allen. “It needs to learn to come back to the breathing hole, to find the breathing hole when it needs to take a breath, how to get in and out of the water.Mom is just keeping the pup company. She’ll help them get out of the water if they need to. They’ll scrape the ice with their teeth to create more traction.”
In addition to swimming lessons, Weddell seal mothers also transfer a huge amount of energy to their pups through their milk without eating anything themselves. In less than two months, a mother Weddell seal sheds around 300 pounds. Specifically, Allen and her colleagues are studying the mom-to-pup transfer of iron, which is what allows the species to hold their breaths for so long.
This huge loss of iron on the part of the mother would be greatly detrimental in humans. But it’s clearly working for Weddell seals, and so Allen and her team are currently investigating the seal-ious enigma.
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