Seals act as the puppies of the ocean, charming humans with their big eyes and playful antics. However, these marine mammals possess incredible survival skills that allow them to thrive in the coldest waters on Earth. They can dive deeper than submarines and hold their breath longer than almost any other air-breathing creature. Furthermore, they navigate murky waters using whiskers that function like high-tech sensors. Prepare to dive in with the pinnipeds.
Seals
The easiest way to tell a seal from a sea lion involves looking at their ears. True seals have tiny holes for ears, while sea lions possess external ear flaps. Additionally, sea lions walk on their front flippers, whereas seals wiggle on their bellies like caterpillars.
They sleep underwater by shutting down half of their brain at a time. This adaptation allows them to rest while still surfacing to breathe or watching for predators. Only when they reach land do they fully shut down both sides of their brain for deep sleep.
Their whiskers detect the wake of a fish swimming up to 600 feet away. Scientists discovered that these sensitive hairs can track prey even in pitch-black water. Consequently, blind seals can survive in the wild just as well as seeing ones.
One species lives entirely in freshwater. The Baikal seal inhabits Lake Baikal in Siberia, thousands of miles from the ocean. No one knows exactly how they got there, but they have lived in the massive lake for two million years.
They can slow their heartbeat to just a few beats per minute. When diving, a seal reduces its heart rate from 100 beats per minute to as low as ten. This extreme physiological change saves oxygen for the brain and heart during deep dives.
Seal milk contains fifty percent fat. Compared to cow milk, which has about four percent fat, seal milk acts like liquid rocket fuel. This richness allows pups to gain massive amounts of weight in just a few days before their mothers leave them.
The Hooded Seal blows a pink balloon out of its nose to impress females. Males possess a stretchy membrane in their nostril that they inflate to look intimidating. This bizarre red bubble shakes when they roar, signaling dominance to rivals.
Leopard Seals act as the only seals that regularly eat warm-blooded prey. While most species eat fish and squid, the Leopard Seal hunts penguins and even other seal pups. Their reptile-like jaws make them formidable predators in the Antarctic.
Weddell Seals sound like sci-fi spaceships. Their calls include trills, chirps, and laser-like zaps that echo under the ice. These strange noises help them establish territory and attract mates in the dark polar winter.
They store oxygen in their muscles, not just their lungs. Seals have much higher levels of hemoglobin and myoglobin than humans. This allows them to exhale before diving to prevent the bends, relying on the oxygen stored in their blood instead.
Mothers recognize their pups by their unique call within minutes of birth. In a colony with thousands of noisy seals, a mother must find her specific baby instantly. If a pup tries to steal milk from the wrong mother, the female will often bite or chase it away.
Southern Elephant Seals can hold their breath for two hours. They dive nearly a mile down to hunt for squid in the abyss. This incredible endurance makes them the champions of breath-holding among all marine mammals.
They use “counter-current heat exchange” to keep their body warm. The veins and arteries in their flippers sit close together, transferring heat from warm blood to cold blood. This system prevents them from losing body heat to the freezing water.
They sometimes swallow stones to help grind up food. Gastroliths, or stomach stones, sit in their belly and crush the shells of crustaceans. Some scientists also believe the stones act as ballast to help them control buoyancy.
Finally, Harbor seals slap the water to show who is boss. Instead of vocalizing, males often slap their flippers against the surface to display strength during mating season. This percussion signals to other males to stay away from their territory.
