Skeletons and Movement

​I. SUPPORT

• Structures for support in animals include skeletons (inside the animal) and exoskeletons (outside the animal).

• Both skeletons and exoskeletons hold the animals body up (support it) and give it shape.

​II. ​EXOSKELETON

• An exoskeleton is a hard, external shell that covers the body of the animal inside.

  • Crabs, spiders, and insects are examples of arthropods with exoskeletons.

    • Don’t confuse all shells as exoskeletons.

      • Turtles and tortoises shells are made from scales that have grown together for protections, and are not exoskeletons.

​III. PROTECTION

• Skeletons, exoskeletons, and scales all provide protection.

  • The brains of animals with internal skeletons are protected by skulls.

  • The ribcage of an internal skeleton also protects the organs of the animal.

  • An exoskeleton protects the entire organism.

  • Skin and scales also provide protection for animals

    • scales are hard plates that grow on the outside of reptiles, fish, and the feet of birds.

​IV. MOVEMENT

• Animals with skeletons use the skeleton working with muscles to move

  • Mammals have combinations of legs, arms, and tails that can be used to provide motion.

  • Many reptiles also use legs for motion.

  • Alligators have long tails that they use to swim with.

  • Turtles have fins to help them swim.

  • ​Birds have two legs that can be used for walking, and two wings that can be used for flying.

  • legless reptiles use their entire body to move.

    • Remember: all reptiles have internal skeletons with backbones, including snakes, and are classified as vertebrates.