The term was then exported with Prussian officers and nobles to Russia. The Feldsher system of rural primary care provided some of the inspiration for China's barefoot doctors. Today feldshers can be found in every medical setting from primary to intensive care. They are often the first point of contact with health professionals for people in rural areas.
1 The prospect of a food chain minus its apex predators may mean the end of the line for many more species. 2  Sharks have widespread global distribution, are highly migratory and play a vital role in maintaining the health of ocean ecosystems.
But they do have extra large livers, which provide some buoyancy and help keep them sinking to the ocean floor. But fresh water changes how much buoyancy the shark's liver can provide. The researchers found that when sharks swim in fresh water, they are two to three times less buoyant than when they swim in salt water. In order to keep afloat the same way they do in salt water, sharks would need livers eight times as largeâunrealistic for an organ thatâs already the largest in a sharkâs body.