Evolution is the process by which this occurs and it is spread out over many generations. Thus, the short minimal definition of biological evolution is, Evolution is a process that results in heritable changes in a population spread over many generations. This is a good working scientific definition of evolution; one that can be used to distinguish between evolution and similar changes that are not evolution.
Bone, cartilage, or dentine is used in the Ostracoderm fish and turtles. Chitin forms the exoskeleton in arthropods including insects, arachnids such as spiders, crustaceans such as crabs and lobsters (see arthropod exoskeleton), and in some fungi and bacteria. Calcium carbonates constitute the shells of molluscs (see Mollusc shell), brachiopods, and some tube-building polychaete worms.
Horseshoe crabsâ eggs are still used as eel bait. in a small fishery supporting U.S. and European markets. 4. The chitin of horseshoe crab shells is extremely pure, and chitin-coated. sutures reduce healing time in humans by 35-50%. A Japanese company. spins pure chitin dressings for burns, surface wounds, and skin-graft donor. sites.