Did You Know Sea Lions Are Warm-Blooded Animals, Just Like You?
A sea lion maintains a core body temperature between 95 and 98 degrees, which is only slightly lower than a person’s. Unlike a person, however, sea lions are capable of swimming all day in freezing cold water. How is that possible?
Sea lions have unique adaptations that allow them to maintain their high body temperature while swimming around in icy water. The first of these is a thick blubber layer, which is approximately an inch thick. Covering that blubber is tightly packed fur. Finally, oil is secreted from a sea lion’s skin. This oil waterproofs the fur, preventing water from getting through. In essence, a sea lion’s skin beneath the fur stays mostly dry, even while they are underwater! This combination of blubber, fur, and oil forms a very efficient wetsuit. These layers help keep the body heat in.
But even with this wetsuit, a sea lion can get cold. South American sea lions, like our boys, swim around in water that comes up from Antarctica. That’s cold! Luckily, sea lions have a special skill that allows them to warm up. This skill is called thermoregulation, and all sea lions can do it. If you inspect a sea lion closely, you’ll notice that the tips of their flippers are devoid of either blubber or fur. The blood vessels at the ends of the flippers are exposed. When a sea lion gets cold, they simply float at the surface of the water with their flipper in the air. The sun heats up the blood in the flipper, and that warm blood pumps throughout the sea lion’s entire body, insulated by their blubber! In the wild, it’s common to sea dozens of sea lions floating together on the water’s surface with their flippers in the air, just warming up.
Thermoregulation works the opposite way as well. A sea lion lying on beach will overheat quickly (you would too if you weighed 500 pounds and was wearing a fur coat on the beach). However, laying on a rock and dipping a flipper in the water serves as a great way to cool off. The ice water cools the sea lion’s blood and brings their temperature down. And if that’s not enough, a quick swim will do the trick.