You may have heard that it's shark week on one of the networks. You may have also heard that one of our inhumane practices is shark finning, where sharks are caught and their fins are sliced off for shark fin soup -- the rest of the shark is discarded. Because sharks are apex predators, overfishing of sharks has a destructive effect on ocean ecosystems. They are also evolutionary survivors, dating back 200 million years into the geological records. In fact, in the 17th century, when Nicolas Steno dissected a shark's head he found that its teeth resembled the triangular-shaped "tongue stones" commonly found embedded in rocks, thus opening the door to the interpretation of these "tongue stones" as the fossilized remains of once-living creatures.Here's what shark finning is all about thanks to Earth Hour's helpful infographic on Pinterest. Read to the end to see how high shark fins are in mercury. Ready to start calling restaurants in your area and ask them to stop serving shark fin soup? You can find a list at stopsharkfinning.net . (Want a bigger version than below? Clicking all the way through will bring you here , which is large and legible).