Seals' Secret to Deep Dives: Oxygen Over CO2

Ever wondered how seals can swim so deep and for so long without passing out? Scientists wanted to know too. They thought it had something to do with carbon dioxide (CO2) levels in the seals' bodies. After all, in humans, high CO2 levels trigger the urge to breathe. But seals don't seem to have this problem. So, researchers decided to study six grey seals in a special tank. This tank had a feeding area and a dome-shaped breathing spot. The seals could swim around and hunt for food, then come up to the dome to take a breath. It was like a mini ocean with a built-in air pocket. The scientists filled the dome with different mixes of oxygen and CO2. They started with normal air, then changed the amounts of oxygen and CO2. They wanted to see how these changes affected the seals' diving time. They expected that high CO2 levels would make the seals surface sooner, just like in humans. But that's not what happened. Surprisingly, the CO2 levels didn't change how long the seals stayed underwater. But low oxygen levels did. This means seals don't rely on CO2 to tell them when to breathe. Instead, they monitor their oxygen levels. When their oxygen gets low, they decide it's time to surface. This way, they avoid the risk of drowning. This discovery shows that seals have a unique way of managing their breaths. Unlike humans, they don't rely on CO2 levels to trigger breathing. Instead, they use oxygen levels to make a conscious decision about when to come up for air. This is a clever trick that helps them stay safe while hunting deep underwater.