Seals use holes in the ice to breathe because they spend most of their time in the water and need to come up to the surface to take in oxygen.
Under the ice, seals hold their breath to hunt but must regularly return to the surface to breathe. The holes in the ice provide them with essential access points to oxygen. These holes are sometimes natural or actively dug by the seals themselves using their claws and teeth. During the Arctic winter, when the ice can nearly cover the water's surface, these openings become vital. Seals maintain several spaced holes that they visit regularly, somewhat like gas stations to fill their lungs with fresh air. The constant availability of these access points determines their survival in an extreme environment where breathing is not a luxury but a vital necessity.
Seals use the holes in the ice as essential support points during underwater hunting. When they dive to catch their prey, they must constantly ensure they can quickly resurface to breathe. These holes then become sort of oxygen refueling stations, where they can catch their breath before heading back out in pursuit of fish or squid. Since the ice floe is often thick and extensive, accurately identifying the location of each hole is crucial to avoid getting stuck without air under the ice. Thanks to these strategic points, they can expand their hunting territory while minimizing risks.
Seals can hold their breath for 20 minutes or more because they have muscles rich in myoglobin, a molecule that efficiently stores oxygen. Their heart rate slows down significantly during dives to conserve oxygen. Additionally, to ensure they can easily find their breathing holes, some seals regularly maintain these holes, constantly scraping to prevent them from freezing. Some even go so far as to create multiple holes in case their main access closes! These animals have also developed remarkable spatial memory, allowing them to quickly pinpoint the exact location of their breathing holes, even under the ice.
Breathing holes allow seals to remain unnoticed by predators like polar bears or orcas. By coming up only through these narrow holes, seals greatly limit their exposure on the surface, reducing the chances of being spotted. A small, unique hole on a vast expanse of ice doesn't really draw attention. Predators more easily spot seals when they come up onto the ice, so these discreet openings become vital refuges for them. By staying close to the holes, seals can quickly escape underwater in case of an alert, giving them a decisive advantage in terms of survival.
In winter, female seals often use these breathing holes as access to dens under the snow, where they can give birth to their young sheltered from the elements and predators.
Seals have an astonishing ability to slow their heart rate when they dive, thereby reducing their oxygen consumption for longer dives.
The breathing holes of seals are sometimes exploited by predators like the polar bear, which patiently waits near these openings to launch a surprise attack.
Some seals actively maintain their breathing holes by regularly scratching and nibbling on the ice to prevent them from freezing completely.
Yes, some species of seals, like the Weddell seal, actively maintain their own breathing holes by scraping and biting at the ice to ensure a constant opening for air.
Thanks to their excellent sense of direction, heightened sensitivity to sounds, and particular light effects under the ice, seals can accurately locate their breathing holes to surface regularly for air.
Yes, polar bears in the Arctic use this strategy by waiting motionless near breathing holes to catch seals when they come up to the surface to breathe.
Typically, a seal can use several breathing holes over time, both to reduce the risks associated with predators and to ensure optimal oxygen availability during their underwater activities.
Depending on the species, seals can hold their breath for 10 minutes to over an hour. Weddell seals, for example, can stay submerged for about 80 minutes thanks to special physiological adaptations.
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