What are the Similarities and Differences Between Human and Animal Skeletons

Human and animal skeletons are two types of hard structures in the body whose main function is to provide structural support while aiding locomotion. However, there are some similarities and differences between human and animal skeletons. Humans are vertebrates and have an endoskeleton made up of bones and cartilage. Meanwhile, other animals like arthropods have an exoskeleton and invertebrates have a hydrostatic skeleton. Furthermore, the growth of the endoskeleton stops at maturity while arthropods shed their exoskeleton several times during their lifetime.

Key Areas Covered

1. What is Human Skeleton
     – Definition, Facts, Structure
2. What is Animal Skeleton
     – Definition, Types, Function
3. What are the Similarities and Differences Between Human and Animal Skeletons
     – Outline of Common Features and Comparison of Key Differences

Key Terms

Animal Skeleton, Backbone, Endoskeleton, Exoskeleton, Human Skeleton, Hydrostatic Skelton, Skull

What is Human Skeleton

Human skeleton is the structural framework of humans. Therefore, its main function is to provide structural support to the body. Also, it aids in the movement of the body. Since human skeleton occurs inside the body, it is an endoskeleton. The human skeletal system contains bones, joints, ligaments, and muscles.

Bones

Bones are a strong tissue, which is lightweight. They are able to grow and repair themselves. The periosteum or the outer layer of bones contains both nerves and blood vessels. Hard, compact bones occur beneath the periosteum. Calcium phosphate and collagen fibers are the structural components of these compact bones. The central part of the bone is made up of spongy bones, which are soft and porous.

Figure 1: Human Skeleton

Human skeleton consists of 206 bones, grouped into long bones, short bones, flat bones, and irregular bones. At birth, it contains around 270 bones, but this number gets reduced by adulthood with the fusion of some bones. Some of the main bones in the human skeleton are skull, vertebral column, ribs, sternum, humerus, radius, ulna, pelvis, femur, tibia, etc.

Joints

A joint or an articulation is a place where two bones meet in the body. Shoulders, elbows, wrists, hips, ankles, and knees are some of the major joints in the human skeleton. Moreover, they aid the movement of bones by allowing bones to pivot, twist, rotate, hinge, or slide. In synovial joints, bones articulate by means of a cartilage. Moreover, these joints contain a cavity filled with a fluid.

Figure 2: Joint

Ligaments

Ligaments are bands of fibrous connective tissue, which hold bones or cartilages together in a joint.

Muscles

Muscles are bundles of fibrous tissue with the ability to contract. Along with bones, they produce voluntary movements. Here, muscles attach to the bones through a tendon.

What is Animal Skeleton

Animal skeleton is the structural framework of animals. Based on the structure, three types of skeletons occur in animals: endoskeletons, exoskeletons, and hydrostatic skeletons.

Endoskeleton

Endoskeleton is the internal skeleton made up of bones and cartilages. It occurs inside the body of vertebrates, including humans, mammals, birds, reptiles, amphibians, and fish. Moreover, it develops from the endoderm and is a living structure. It grows as the body grows and a single skeleton is maintained throughout the lifetime of the animal.

Figure 3: Endoskeleton

The two main parts of the endoskeleton are axial skeleton and appendicular skeleton. The axial skeleton consists of the skull and backbones. The main function of the skull is to protect the brain. Backbone protects the spinal cord. The appendicular skeleton provides support to the appendages while protecting internal organs.

Though the main function of the endoskeleton is to provide structural support and aid in the movement, it also involves in the protection of internal body organs. In addition, it produces blood cells in a process called hematopoiesis. Also, the bone matrix serves as a storage compartment of calcium, iron, ferritin, and phosphate. In addition, bone cells perform an endocrine function by secreting hormones like osteocalcin, which regulates blood sugar levels and fat deposition.

Exoskeleton

Exoskeleton is the external skeleton of arthropods; it is made up of chitin. It occurs in diplopods, chilopods, arachnids, crustaceans, and insects. The main characteristic feature of the exoskeleton is its molting. Arthropods have to shed their skeleton since it occurs outside the body and prohibits the growth of the body. Therefore, they develop several exoskeletons during their lifetime. In addition, mollusks have an exoskeleton made up of calcium compounds. However, they do not shed their skeleton.

Figure 4: Exoskeleton

Hydrostatic Skeleton

Hydrostatic skeleton is a fluid-filled compartment inside the body called coelom. Here, hydrostatic pressure is the main factor which provides structural support. Also, it supports the internal organs. This is found in invertebrates with soft bodies like sea anemones, earthworms, and cnidarians.

Figure 5: Hydrostatic Skeleton

What are the Similarities and Differences Between Human and Animal Skeletons

The following section looks at both similarities and differences between human and animal skeletons. 

Similarities Between Human and Animal Skeletons

• Human and animal skeletons are two types of hard structures which provide structural support to the body.
• They also aid in locomotion.
• Both types of skeletons grow in size with time and reach a steady state.
• Humans are vertebrates, who have an endoskeleton made up of bones and cartilage.
• The two main parts of the vertebrate skeleton are the axial skeleton and the appendicular skeleton.
• Skull and backbone are the two main parts of the axial skeleton. Meanwhile, the appendicular skeleton protects the internal organs while providing structural support and the aiding the movement.
• Most vertebrates and humans share basic bones and muscles but in different proportions and ratios.

Difference Between Human and Animal Skeletons

Definition

Human skeleton refers to the internal framework of the human body, composing of 206 bones, while animal skeleton refers to a usually rigid supportive or protective structure or framework of an organism.

Types of Skeletons

The human skeleton is an endoskeleton while vertebrates have an endoskeleton, arthropods have an exoskeleton, and invertebrates have a hydrostatic skeleton.

Growth of the Skeleton

The growth of the endoskeletons like human skeleton stops at some point and maintains a steady state while exoskeleton is shed after the growth.

Conclusion

The human skeleton is an endoskeleton, which occurs inside the body. It resembles most endoskeletons of vertebrates. Other animals like arthropods have an exoskeleton while invertebrates have a hydrostatic skeleton. Moreover, both human and animal skeletons are two types of hard structures which provide structural support to the body, while aiding in locomotion. These are the main similarities and differences between human and animal skeletons.

References:

1. “Types of Skeletal Systems|Boundless Biology.” Lumen Learning, Lumen, Available Here

Image Courtesy:

1. “Human-Skeleton” By Sklmsta – Own work (CC0) via Commons Wikimedia  
2. “Joint” By Madhero88 – Own work Info sites 1 2 3 (CC BY-SA 3.0) via Commons Wikimedia  
3. “Types of Skeletal Systems” By OpenStax College (CC BY 3.0) via OpenStax CNX
4. “Gecarcinus quadratus (Nosara)” By (Bhny) – http://en.wikipedia.org/wiki/Image:HalloweenCrab.JPG (Public Domain) via Commons Wikimedia  
5. “Types of Skeletal Systems” By OpenStax College (CC BY 3.0) via OpenStax CNX