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.
Most species of sharks have five pairs of gill slits on each side of their head, but a few have six or seven pairs. The gills are crucial to a sharks breathing system. By opening its mouth, water is drawn into the shark. The open mouth gives the appearance of a smile in many sharks. When a shark closes its mouth, the water is forced over its gills and the tiny blood vessels in shark gills absorb oxygen from the water. To aid water flowing over its gills most sharks swim forward all the time, called ram ventilation, and is characteristic of more active open ocean sharks.