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Animal Systems


Skeletal systems come in many forms. You have a skeleton inside of your body (endoskeleton) made up of bones. Insects and crustaceans have skeletal systems on the outside or their bodies (exoskeletons) that are made of hard plates.

Skeletons hold up the structure Organisms like starfish do not have bones or plates. They have skeletons made up of fluids inside of tubes within their bodies. The fluid skeletal systems are called hydrostatic. All animals that live outside of the water need some kind of skeletal system to support or protect them.


We already hinted at the purpose of a skeletal system. Protection and support are the two big reasons that organisms have skeletal systems. In your body, the skeleton works very closely with the muscular system to help you move. Without the bones of your skeleton, you would be a blob of water-filled tissues. The bones create a framework to which your muscles and organs can connect. Your skeleton also plays a role in protection, especially in your head. The bones of your skull protect your all-important brain. Your ribs protect most of your internal organs from impact as well. Other animals with exoskeletons receive obvious protection from their skeleton. Crabs and insects have hard shells made of chitin to protect their entire bodies.

Structure of bone


Your skeletal system does not work alone. We already mentioned the interaction with your muscular system. Muscles connect to your skeleton and they contract and move the skeleton along. Your skeletal system is made up of cartilage and calcified bone that work together. They help the process of movement happen in a smoother manner. The calcified bones of your skeleton also work with the circulatory system. Marrow inside of your bones helps produce the cells inside of you blood. Both red blood cells and white blood cells are created in your bones.


Location of yellow marrow Sometimes your skeletal system and the tissues of your skeleton can have problems. Some genetic diseases cause individuals to grow excessive large and thick bones. Acromegaly is the term used to describe a condition that affects the pituitary gland and causes an excessive amount of growth hormone to be produced.

Other diseases cause problems with bone formation and related connective tissues including collagen. These genetic diseases can cause bones to become brittle and break easily, while the collagen of the body does not have the strength of a healthy individual. If everything is working correctly, bones are able to break and then heal. Even older people who break their bones can grow new bone and connective tissue that returns the bone to a usable state.

Related Activities

Animal Systems Quiz General Animal Systems Quiz
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Skeletal System Quiz Skeletal System Quiz
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- Overview
- Regulation
> Skeletal
- Muscular
- Circulatory
- Respiratory
- Digestive
- Excretory
- Nervous
- Endocrine
- Integumentary
- Immune
- Lymphatic


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