Seals are so agile underwater because of their streamlined body, webbed limbs, and thick layer of fat that allows them to move quickly and efficiently in the water.
The bodies of seals are shaped like a torpedo, tapered at the front and rounded at the back, which greatly reduces resistance in the water. Their front limbs, called pectoral flippers, are primarily used for steering and stabilizing their swimming, while their back limbs, known as hind flippers, provide the majority of propulsion through a very flexible undulating movement. A flexible spine allows them to change direction quickly with ease and grace underwater. The distribution of their body fat, referred to as a blubber layer, helps improve their buoyancy and balance for easy movement underwater.
Underwater, seals move by means of smooth undulations of their bodies and hind flippers. It's as if they glide fluidly in a natural and elegant motion. Their front flippers primarily serve to steer and stabilize their trajectory with speed and precision. The combination of a streamlined body, powerful musculature, and well-adapted movements makes them exceptional swimmers, capable of sharp and rapid changes in direction. They use their natural flexibility to turn, dive, or surface with apparent ease, as if they are dancing underwater.
Seals have a dense fur that traps a layer of air against their skin, helping them move through the water with very little resistance. Their short, sleek, and tightly packed hairs reduce turbulence in the water, making them super fluid when they swim. It's a bit like a high-performance wetsuit: it allows for better glide and limits heat loss. This special coating combined with their thick layer of fat, called blubber, ensures top-level thermal insulation and perfect gliding, helping these animals to dart through the water with surprising ease.
Seals primarily use their vibrissae, a type of hypersensitive whiskers capable of detecting the slightest movements or vibrations around them. Thanks to these true integrated tactile radars, they easily locate fish and prey, even in dark or murky waters. Their eyes, adapted to low underwater light, have a reflective layer behind the retina, the tapetum lucidum, which acts like a mirror to amplify the available light. Their hearing is also finely tuned, allowing them to hear very subtle underwater sounds, thus facilitating their orientation and hunting in depth.
Seals can hold their breath for a long time thanks to their large lung capacity. During dives, their heart rate drops significantly to conserve oxygen: this is known as diving bradycardia. In addition, their blood carries a large amount of oxygen due to a higher number of red blood cells and myoglobin (a protein in muscles that binds oxygen). This system allows them to dive very deep, sometimes several hundred meters, and stay down for a long time without having to come up to breathe constantly. This is useful for hunting quietly underwater!
The whiskers of seals, known as vibrissae, are capable of detecting the movements of a fish from over 30 meters away, making them exceptional aquatic predators.
The fur of seals has a double layer that provides both thermal insulation and reduced friction in the water, allowing them to swim efficiently even in icy waters.
Seals have a special anatomical characteristic: their nostrils automatically close as soon as they dive, preventing water from entering their respiratory system.
When the seal dives deeply, its heart rate drastically slows down to conserve oxygen, dropping from 100 to less than 10 beats per minute.
Generally, seals can stay underwater for 10 to 30 minutes, but some species can extend this duration to nearly two hours due to their enhanced oxygen storage capacity and a metabolism that can slow down significantly during prolonged dives.
The vibrissae, or whiskers, of seals act as ultra-sensitive sensory receptors to detect vibrations caused by the movement of potential prey, facilitating navigation and hunting even in murky or dimly lit waters.
Yes, the dense fur of seals acts as an effective thermal insulator due to its thick and tight undercoat, which traps air bubbles naturally heated by body warmth, thus protecting the seal from the freezing temperatures of the deep sea.
Seals primarily use their hind limbs to propel themselves underwater with powerful, undulating movements, while sea lions favor their forelimbs for swimming. This distinction gives them very different swimming styles.
Seals swim horizontally to make the most of their streamlined bodies, which significantly reduces water resistance and increases their energy efficiency, thereby facilitating their fast and smooth underwater movements.
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