Deep diving fur seals experience delayed heart surges after returning to land

Fur seals may look like they’re simply resting after exhausting hunting trips at sea, but their bodies are secretly working overtime. Scientists discovered that hours after returning to land, the seals’ heart rates suddenly surge — sometimes doubling — as they recover from the intense physical stress of deep diving. The findings suggest that seals postpone much of their recovery until they’re safely ashore, likely flushing out lactic acid and rebuilding oxygen stores after days of nonstop diving and hunting.