Environment & Adaptations
Some scientists believe that sharks are the descendants of Placoderms, which are ancient jawed fish that have a derma skeleton. Over time sharks have lost the ability to produce bone so most of their body is cartilage and the only bone they have is their backbone. Sharks have adapted to swim faster and protect themselves with the help of placoid scales, these scale are smooth when rubbed from back to front and give the shark a more streamline figure to swim faster. When rubbed from back to front they are rigid and act as a form of armor. Male sharks have developed claspers which hold sperm for mating, up until this adaptation it is unknown on how sharks mated.