How Some Animals Survive for Hours Without Any Oxygen

Oxygen is essential for almost every animal on Earth. Humans can survive only a few minutes without it before serious damage begins to occur. Yet nature has evolved a handful of extraordinary species that can endure hours, days or even months with little or no oxygen. Living in frozen lakes, muddy ponds and oxygen-starved wetlands, these remarkable animals have developed survival strategies unlike anything found in humans. Some slow their metabolism to an astonishing degree, while others switch to completely different chemical processes to keep their cells alive. Their unique abilities continue to fascinate scientists and could one day inspire new treatments for medical emergencies involving oxygen deprivation.