The skeletal system

                                                              The skeletal system

          The skeletal system is very important to living organisms and it helps our bodies with support and protection for organs, movement, blood cell production, and mineral storage. Without the skeletal system, we would probably move like noodles and our bodies wouldn't have enough protection or support. There are 3 types of skeletons:

• Hydrostatic: occurs in soft-bodied animals (Ex. Earthworms)
• Exoskeleton: hard, non-living structure that protects entire body (Ex. crayfish)
• Endoskeleton: cartilaginous and bony skeleton of body (Ex. humans, rats) Endoskeletons is the inside support structure of an organism that helps protect the internal organs and allows the body for easier movement and doesn't need to be replaced or removed as the organism grows.

     The earthworm doesn't have a skeleton, otherwise known as a hydrostatic skeleton. The worm has bristles on each segment that helps the worm move. Worms have no limbs and they have two muscles. One of the muscles makes the worm long and thin. The other muscle makes the worm fat. Earthworms are a great example of hydrostatic because their advantages of having a hydrostatic is that they have no bones and they have more movement, which helps them have easier access to get into small areas and it's easier for them to move around more and be more flexible. The earthworm's disadvantages is that they have no support and no protection and they have no stability, which causes them to get killed easier and won't be able to fight back predators or hold and pick up objects. Having a hydrostatic skeleton is very different to having a exoskeleton like the crayfish does and also endoskeleton like what humans, rats, and frogs have because it doesn't provide much protection.


Crayfishes are invertebrates meaning that they don't have a backbone. Their bodies are segmented  like the worm for flexibility and movement and they have a exoskeleton. The advantages of having a exoskeleton is very good because it provides protection from predators and the environment (Ex. windstorms, rain, snow, etc.), provides camouflage (Ex. a turtle can be inside its shell and stay still to make itself look like a rock), and also has space for muscle attachment. Their advantages helps them survive better because their exoskeleton protects them from hurting their internal organs and to avoid being hurt or eaten from their predators and environment, helps them hide from being hunted from other animals, and have no damage to their bodies. The disadvantages for the crayfish are body weight, limited growth for the organism, and less movement. Their disadvantages doesn't help them survive because  their body structure that can lower their rate of movement and they have limited growth because their body structure isn't big enough to allow them to get bigger also they have less movement because it's harder for them to move inside and it's difficult for them to regulate their body temperature.


         The grass frog has the same type of skeleton like the rat and humans, which is a endoskeleton. The frog has a backbone that has five to nine vertebrate and have a short, stiff neck that has limited mobility. The frog's jaw is made to grab things instead of chewing them and has a large tongue extension. They have no ribcage to provide protection for their inner organs for the frog. The frog has long legs for jumping and swimming. The frog is quite similar and a bit different compared to the human's skeletal system  because frogs have the same bone structure as humans like the phalanges, metacarpals and carpals that make up the hands and wrists. Frogs are different because they have no ribcage to protect their inner organs like the humans and rats do. another difference is that frogs have a total of 159 bones and humans have 206 bones.

            The advantages of having an endoskeleton is that it has ability to support larger size and weight, bones are inside, bones can heal when broken, and more movement. The endoskeleton has no limited growth or weight, bones are inside so they can protect the internal organs, our bones heal by our cells, and we have movement to move and to pick and hold things and to be stable. The disadvantages of having a endoskeleton is it can cause damage and pollution, our flesh is outside, and whatever caused a broken bone, it also damages the muscle and skin. The reasons for the disadvantages is because it's easier to get bruises and bumps, impossible to grow a new skeleton, causes damage to skin ( Damage from environment and pollution: sun, smoke),  and a broken bone can also cause damage to muscle and skin (which explains the bruises and bumps).

 
          Rats and humans are very similar but also different in a few ways. Rats have 233 bones unlike humans have 206 but their bodies are both divided into axial and appendicular skeletons. Humans and rats both have endoskeleton and have the same axial structure of bones like the skull, sternum, and ribs. The rat's ribcage covers a huge amount of the animal and its feet has only 4 fingers which means it has a few bones less than the human and their skeleton is much weaker compared to humans.