churn in Business English. churnnoun [ U ] Preventing customer churn is a major concern for mobile service providers, since 20-40% of customers leave their providers in a given year. Employee churn for new hires increased by 33% for the third straight year.
For 18 months, the baby nurses while its mother is on land, or it swims underwater to suckle. When it dives, the calf closes its nose and ears to block out water. All hippos have this ability. They also have membranes that cover and protect their eyes while they are underwater.
To stop using so much oxygen, diving mammals can stop their breathing and shunt blood flow from their extremities to the brain, heart, and muscles. They also shut down digestion, kidney and liver function. Finally, they lower their heart rate. Most mammals can do this when they dive, even humans.