Seal, you can swim, why are you always pulled out of the water?

Have you watched the recently popular animation Sealook? The main characters in the animation are all cute leopards, but as a nature lover, I couldn't help but notice many details in the animation.

For example - the occasional round holes that appear in the ice.

Seals and Ice Caves | Sealook

Such ice caves often appear in emoticons, and a fresh leopard (not really) can be pulled out of the hole.

It's like me who doesn't want to go to work

These ice holes are the seals’ life-saving passages: breathing holes .

Seals are masters of diving and fishing, but as mammals, they still have to return to the surface of the water to breathe, otherwise they will drown. It is certainly feasible to breathe in the sea surface or in the cracks of the ice, but if there is a large piece of continuous sea ice above, they can only rely on their breathing holes.

A Weddell seal resting in its breathing hole looks very comfortable｜Youtube

The Weddell seals (Leptonychotes weddellii) in Antarctica like to dive for a long time under the solid ice. It is said that when they rest on the ice, they usually do not leave their breathing holes more than three meters away. For seals, the breathing holes are their life doors.

Learning to find breathing holes is more important than learning to hunt.

Weddell seal pups have to swim in the icy sea two weeks after they are born. The first thing they have to learn at this time is to find the breathing hole , which is even more important than eating.

In a study published in 2021, scientists compared the behavior patterns of young seals and adult seals in the sea and believed that young seals and adult seals practiced navigating and finding breathing holes under the ice while swimming in the water. They are not sure about the role of mother seals in this process, but it is likely a teaching behavior.

A Weddell seal pup rests at its blowhole with its mother between swim lessons | Linnea Pearson

Adult Weddell seals can hold their breath for up to 1.5 hours , which is the longest among the seal family, but pups rarely stay underwater for more than ten minutes. Drowning due to insufficient swimming ability or inability to find a breathing hole is one of the main causes of death for Weddell seal pups.

How does the saying go? Those who drown are those who can swim...

Digging an ice cave is not possible with bad teeth

Adult Weddell seals have another responsibility, which is to maintain and defend their breathing holes.

When the temperature drops and the ice cave shrinks due to ice formation, the seals have to soak in the cold sea water and rub their jagged incisors and canines to widen the hole.

Seal Shaved Ice｜Youtube

People with sensitive gums will probably feel pain when seeing this picture. In fact, seal teeth can't stand such torture.

At around 20 years old, they die because their teeth wear out and they are no longer able to hunt or repair their ice holes. "If evolution could create a perfect adaptation, it would give seals teeth that grow continuously, just like rodents!" American biologist Jerry Coyne wrote in his blog.

Weddell seal skull showing incisors and canines (arrows) worn down to the pulp cavity, and two abscesses in the maxillary bone (the right canine was removed to determine age) | BM Dukes

Perhaps evolution has been kinder to the ringed seal (Pusa hispida). Ringed seals use their front paws to dig their breathing holes , which sounds more reasonable than gnawing with their teeth. It would also be easier to start construction in cracks and weak spots in the ice.

The breathing holes are not only the seals’ breathing holes, but also the entrances for fishing. For seals living in the Arctic, the breathing holes can also help them escape quickly when polar bears appear. However, polar bears will also guard the ice holes, waiting for the unlucky seals.

Although I would like to find more videos of Arctic seals digging breathing holes to share with you, the Weddell seal is the most studied in this regard. This is partly because different seals have different behaviors, and partly because the Weddell seal activity area is close to the Antarctic research station, making it easier to study.

Polar animals still have many unknown secrets, but climate change is threatening their lives. Seals not only rely on ice to live and reproduce, but some of them also dig holes in the ice to raise their offspring. Climate change will cause drastic changes in their habitats and affect their food sources.

Fight climate change and prevent the melting of glaciers from flowing into the ocean. Leopards are good, and so are people.

References

[1]https://academic.oup.com/jmammal/article/102/4/1000/6290999?login=false#285787621

[2]https://www.eurekalert.org/news-releases/824652

[3]https://whyevolutionistrue.com/2019/08/14/weddell-seal-chews-breathing-hole-in-the-ice/

[4]https://www.fisheries.noaa.gov/species/ringed-seal

Author: Maya Blue

Edit: Flip

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