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.
Fossil Shark Teeth. Shark teeth are made of a solid substance called dentin. This material is slow to decompose, which is part of the reason why fossil shark teeth are so plentiful. When a shark loses a tooth, it ends up on the bottom of the ocean, where it's covered with protective layers of sediment.hark teeth are made of a solid substance called dentin. This material is slow to decompose, which is part of the reason why fossil shark teeth are so plentiful. When a shark loses a tooth, it ends up on the bottom of the ocean, where it's covered with protective layers of sediment.